No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Quantitative estimation of the impact of caprine arthritis encephalitis virus infection on milk production by dairy goats
... [7][8][9] In addition to these, the impact on milk yield has been investigated in both sheep and goats, but with varying results. Estimates of total milk production losses in goats vary from not significant to 22.7%, [10][11][12][13][14][15][16] while milk production estimates in sheep vary from an increase of 18% to a decrease of 30% . [17][18][19][20][21] Multiple factors have been identified as playing a role in milk yield changes in infected animals, such as SRLV-induced mastitis and reduced lactation periods. ...
... [17][18][19][20][21] Multiple factors have been identified as playing a role in milk yield changes in infected animals, such as SRLV-induced mastitis and reduced lactation periods. 14,22,23 It has also been suggested that lower growth rates observed in lambs infected with SRLV can be attributed in part to reduced milk yields and indurative mastitis associated with infection. 24 Measurement of somatic cell count (SCC, mostly macrophages, leukocytes and lymphocytes) in milk is a common proxy method for estimating mastitis (bacterial or viral infection) levels in ruminants. ...
... Previous estimates of milk production losses in dairy sheep and goats vary considerably from not significant to 30%; however, a variety of breeds, production systems and recording systems have been used across studies. [10][11][12][13][14][15][16][17][18][19][20][21] The results of this study support the findings of previous studies in Spanish and Polish sheep production systems, 18,20,21 which are either experimental studies 18 or retrospective studies with similar design and analysis methods to our study. 20,21 On the basis of this evidence, the authors believe it is reasonable to conclude that milk production in dairy ewes can be expected to be reduced by at least 5%, up to potentially over 10% during the early mid-phase of the disease process when animals are seropositive but pre-clinical and not showing any overt signs of respiratory disease. ...
Background:
Small ruminant lentiviruses (SRLVs) are lentiviruses of sheep and goats, formerly known as maedi-visna (MV) in sheep and caprine encephalitis and arthritis in goats. In sheep, SRLVs commonly cause progressive pneumonia, wasting and indurative mastitis. SRLVs have a long latent period, and chronic production losses are often not recognised until very late. Few studies quantifying the production losses in ewes have been published, and none have been published under UK flock husbandry conditions.
Methods:
Production records of milk yield and somatic cell count (SCC) from a dairy flock of 319 milking East Friesian × Lacaune ewes identified as MV infected via routine serological screening for SRLV antibodies were used in multivariable linear regression modelling to estimate the impact of SRLV status on total milk yield and SCC.
Results:
Milk yield was reduced in seropositive ewes by 8.1%-9.2% over an entire lactation. SCC counts were not significantly different in SRLV-infected and unifected animals.
Limitations:
Further parameters, such as body condition score or clinical mastitis, that were not available may have clarified the underlying cause of milk yield drop.
Conclusions:
The study demonstrates substantial production losses in an SRLV-affected flock and highlights the impact of the virus on a farm's economic viability.
... Poland, and Croatia, respectively (Dawson and Wilesmith, 1985;Grewal et al., 1986;Cutlip et al., 1992;Al-Qudah et al., 2006;Vallerand et al., 2007;Ghanem, 2011;Oem et al., 2012;Martínez-Navalón et al., 2013;Stonos et al., 2013;Jones, 2014;Tabet et al., 2015;Tariba et al., 2015;Waseem et al., 2015;Thomann et al., 2017;Yang et al., 2017;Gruszecki et al., 2018). This disease causes major economical and welfare problems for the worldwide goat industry, including reduced production, growth rate, and longevity; greater rate of reproductive failures; premature culling; and increased incidence of disease (Smith and Cutlip, 1988;Peterhans et al., 2004;Reina et al., 2009;Leitner et al., 2010;Murphy et al., 2010;Konishi et al., 2011;Kaba et al., 2012;Tageldin et al., 2012;Martínez-Navalón et al., 2013). ...
... Poland, and Croatia, respectively (Dawson and Wilesmith, 1985;Grewal et al., 1986;Cutlip et al., 1992;Al-Qudah et al., 2006;Vallerand et al., 2007;Ghanem, 2011;Oem et al., 2012;Martínez-Navalón et al., 2013;Stonos et al., 2013;Jones, 2014;Tabet et al., 2015;Tariba et al., 2015;Waseem et al., 2015;Thomann et al., 2017;Yang et al., 2017;Gruszecki et al., 2018). This disease causes major economical and welfare problems for the worldwide goat industry, including reduced production, growth rate, and longevity; greater rate of reproductive failures; premature culling; and increased incidence of disease (Smith and Cutlip, 1988;Peterhans et al., 2004;Reina et al., 2009;Leitner et al., 2010;Murphy et al., 2010;Konishi et al., 2011;Kaba et al., 2012;Tageldin et al., 2012;Martínez-Navalón et al., 2013). Additionally, CAE is a limiting factor for trade of animals across local herds and internationally, as this disease is controlled by biosecurity barriers (Bezerra Júnior et al., 2018). ...
... In addition, CAEV is difficult to eradicate because goats can be seronegative and continue shedding in milk for months postinfection. Thus, we can conclude that CAEV eradication has been a major challenge for the worldwide goat industry (Martínez-Navalón et al., 2013). In this context, some countries and producers have opted for not pursuing testing and eradication programs (White and Knowles, 2013), which results in long-term welfare and economic implications for the goat industry. ...
Caprine arthritis encephalitis (CAE) is a chronic disease caused by a retrovirus from the Lentivirus genus. No effective vaccines or treatments exist, and therefore genetic selection for CAE resistance might be a feasible alternative. To our best knowledge, no other studies have investigated the genetic architecture of CAE resistance in dairy goats. In this context, this study was designed to estimate genetic parameters for CAE infection in Alpine and Saanen goats using a Bayesian threshold model. A total of 542 adult goats (and >3-generation pedigree), which were group-housed in a population with high CAE prevalence, were tested based on a serological infection assessment test (negative = 1 or positive = 2) and used for this study. Genetic parameters were estimated using the BLUPF90 family programs. There was considerable genetic variability for CAE resistance, and pedigree-based heritability was significantly different from zero (0.026 < heritability < 0.128). Our findings indicate that the prevalence of CAE in goat herds can be reduced or eliminated through direct genetic selection for CAE resistance in addition to proper management strategies.
... These diseases cause direct losses, such as decrease in the productive life length and milk production; shorter duration of lactating period; predisposal for bacterial infections especially in the mammary gland; and reduction in fat and protein levels of milk produced by the infected goats, which affect dairy products such as cheese production (SMITH; CUTLIP, 1988;GREGORY et al., 2009;BRITO, 2009;MARTÍNEZ-NAVALÓN et al., 2013). Indirect losses are associated with flock devaluation and commercial barriers for transport of animals and germplasm, such as nannies, bucks, semen, and embryos (PINHEIRO et al., 2001;MODOLO et al., 2003). ...
... Moreover, a study performed with dairy goat flocks in a semi-arid region of Ceará, Brazil, reported an even higher reduction of the milk production estimated in 26% (BRITO, 2009). Based on MARTÍNEZ-NAVALÓN et al. (2013), milk production in seropositive animals decreases with the increase of age. ...
... Some physical factors such as electroconductivity and chloride contents are higher in the milk of infected goats. Moreover, there is an increase in the somatic cell count (SMITH;CUTLIP, 1988;SANCHEZ et al., 2001;BIRGEL JUNIOR et al., 2007;BRITO, 2009;MARTÍNEZ-NAVALÓN et al., 2013). ...
Small ruminant lentiviruses, caprine arthritis encephalitis virus, and Maedi-Visna virus cause diseases that result in significant productive losses, mostly in dairy animals. These viruses belong to the Retroviridae family, Lentivirus genus, and constitute a heterogeneous group, which may generate implications for the diagnosis and control of small ruminant lentiviruses. Losses caused by them are associated with reproductive failure, short productive life, and decreased milk production by the infected animals. In addition, these viruses may reduce milk quality, affecting the production of dairy products such as cheese. Small ruminant lentiviruses lead to indirect losses, decreasing herd value and forcing the development of epidemiological trade barriers for animal germplasm. Control of small ruminant lentiviruses is important to promote optimal milk production and to reduce costs with medicine and technical assistance. This control may vary in caprine and ovine populations of each country, according to seroprevalence, variety of breeds, and peculiarities of the practiced management.
... Small Ruminant Lentiviruses (SRLVs) are viruses of the Retroviridae family that include Caprine Arthritis Encephalitis Virus (CAEV) and Maedi-Visna Virus (MVV) [1]. SRLVs can cause chronic and progressive inflammatory and degenerative lesions to the joints, mammary glands, lungs and central nervous system in both goats and sheep [2][3][4]. Many economic losses have been attributed to SRLV infections, such as a decrease in milk production and milk quality, along with poor animal welfare and premature death [2,[4][5][6][7]. ...
... SRLVs can cause chronic and progressive inflammatory and degenerative lesions to the joints, mammary glands, lungs and central nervous system in both goats and sheep [2][3][4]. Many economic losses have been attributed to SRLV infections, such as a decrease in milk production and milk quality, along with poor animal welfare and premature death [2,[4][5][6][7]. SRLVs have been characterized into five genotypes (A-E), three of which (A, B and E) have been further divided into viral subtypes (A1-22, B1-5, E1-2) [8][9][10]. ...
South Tyrol has implemented, in 2007, a mandatory eradication program against Caprine Arthritis Encephalitis Virus (CAEV), a virus known to cause economic losses related to decreases in milk production and milk quality in goats, along with poor animal welfare and premature death. After a great initial decrease in the seroprevalence, the program has reached a tailing phase with scattered positivities. Potential risk factors associated with the multispecies farming system, a traditional approach in South Tyrol, are evaluated in this study, in order to better understand some of the potential causes leading to the tailing phenomenon. A statistically significant number of farms was selected for the present study, based on the risk factors evaluated. Even though there is no statistically significant association between the practices evaluated and the incidence of infection, the authors believe that it is important to highlight potential risks that may threaten the outcome of this eradication program.
... 2013 [41] 3913 goats in Valencia that were born from September 2005 and January 2008. ...
... In this article [41], the authors used the statistical modelling to investigate the production and the quality of the milk in CAE infected goats. To build the final model, they use a backward-elimination strategy with the Akaike's information criterion (AIC). ...
Mathematical modelling is used in disease studies to assess the economical impacts of diseases, as well as to better understand the epidemiological dynamics of the biological and environmental factors that are associated with disease spreading. For an incurable disease such as Caprine Arthritis Encephalitis (CAE), this knowledge is extremely valuable. However, the application of modelling techniques to CAE disease studies has not been significantly explored in the literature. The purpose of the present work was to review the published studies, highlighting their scope, strengths and limitations, as well to provide ideas for future modelling approaches for studying CAE disease. The reviewed studies were divided into the following two major themes: Mathematical epidemiological modelling and statistical modelling. Regarding the epidemiological modelling studies, two groups of models have been addressed in the literature: With and without the sexual transmission component. Regarding the statistical modelling studies, the reviewed articles varied on modelling assumptions and goals. These studies modelled the dairy production, the CAE risk factors and the hypothesis of CAE being a risk factor for other diseases. Finally, the present work concludes with further suggestions for modelling studies on CAE.
... This single-stranded RNA virus infects monocytes, macrophages, and epithelial and dendritic cells. The infection is lifelong, and it can persist in a latent form for months or years [56][57][58]. This multisystemic inflammatory disease causes arthritis of the carpal joints and (rarely) of the tarsal joints in adult goats, and respiratory distress, mammary induration, and occasionally neurological symptoms (progressive demyelinating encephalomyelitis) in sheep. ...
... SRLV is transmitted vertically (via intake of colostrum or milk from the infected mother) and horizontally (via direct contact with body secretions of infected animals) [63]. SRLV infection causes economic loss due to the premature culling of infected animals and decreased milk yield [57]. Kaba et al. (2011) [64] showed no difference in the level of Hp between infected and uninfected goats; however, they did not distinguish between infected animals with the clinical and subclinical forms of caprine arthritis encephalitis (CAE). ...
We examined acute phase protein (APP) concentrations in viral infections of dairy ruminants and assessed the potential role of characteristic patterns of APP changes in auxiliary diagnosing viral diseases. All viruses reviewed are common causes of farm animal diseases. APPs are among the first agents of immunity, and their concentrations could be diagnostically relevant. In the most common ruminant viral diseases, elevated serum amyloid A (SAA) and haptoglobin (Hp) levels in blood serum have been observed. However, since these proteins are the main APPs in many viral infections, it is impossible to use their levels for diagnosing particular infections. Decreased Cp and albumin expression could help differentiate the bluetongue virus infection from other diseases. Lastly, analysis of SAA levels in blood serum and milk could be helpful in diagnosing small ruminant lentivirus infection. While promising, APP levels can only be considered as an auxiliary tool in diagnosing viral diseases in ruminants.
... However, the milk of uninfected goats contained more total protein, fat, and lactose than that of the infected goats. Martínez-Navalón et al. (2013) studied the Marciano-Granadina breed, which commonly carries CAEV. Longer lactations, higher milk yield, higher fat content, normalized mean SCC, and lactose content were found in seronegative goats. ...
... Longer lactations, higher milk yield, higher fat content, normalized mean SCC, and lactose content were found in seronegative goats. According to their findings, CAEV infection could be a major cause for decreased milk production in dairy goats; however, they mentioned that transmission routes and potential causes of this disease are still unclear and need more research (Martínez-Navalón et al., 2013). ...
In the century of research chronicled between 1917 and 2017, dairy goats have gone from simply serving as surrogates to cows to serving as transgenic carriers of human enzymes. Goat milk has been an important part of human nutrition for millennia, in part because of the greater similarity of goat milk to human milk, softer curd formation, higher proportion of small milk fat globules, and different allergenic properties compared with cow milk; however, key nutritional deficiencies limit its suitability for infants. Great attention has been given not only to protein differences between goat and cow milk, but also to fat and enzyme differences, and their effect on the physical and sensory properties of goat milk and milk products. Physiological differences between the species necessitate different techniques for analysis of somatic cell counts, which are naturally higher in goat milk. The high value of goat milk throughout the world has generated a need for a variety of techniques to detect adulteration of goat milk products with cow milk. Advances in all of these areas have been largely documented in the Journal of Dairy Science (JDS), and this review summarizes such advances.
... No differences were found in fat, lactose and TS concentrations. It was reported that milk from CAE-seropositive dams contained low protein, fat and lactose with or without affecting milk yield (Kaba et al., 2012;Martínez-Navalón et al., 2013). Table 1 The composition of colostrum in colostrum of dams in CONT (CAE-seronegative) and CAE (CAE-seropositive) groups ...
... Dairy flocks seem to be the most affected by these negative impacts. In these, the development of infection can decrease the amount of milk produced by infected animals [35,36] and negatively affect quality parameters and cheese yield [37,38]. Consequently, if there is lower milk production and quality of itself as well, the offspring will also have a lower growth rate [39]. ...
Small ruminant lentiviruses (SRLVs) are transmitted among ovine and caprine species. This disease is a severe problem for small ruminant production, not only for animals’ well-being but also for flocks’ efficiency. The main aim of this research was to quantify the seroprevalence and associated risk factors for SRLV infection in the northern region of Portugal. Samples were collected from a total of 150 flocks, of which 129 (86.0%; 95% CI: 80.67%–91.33%) had at least one seropositive animal. Out of 2607 individual blood samples, 1074 (41.2%) were positive for SRLVs. Risk factors associated with SRLV infection were species (caprine), age (>2 years old), flock size (>100 animals), production system (intensive), food production system (milk), type of activity (professional), participation in livestock competitions (yes), replacement young ewe bought (yes), and natural feeding management (yes). This knowledge empowers the implementation of effective preventive measures. Overall, biosecurity measures should be promoted and implemented with the main aim of reducing viral transmission and reducing the prevalence of this disease. We recognise that government authorities should promote and audit voluntary control and eradication programs in small ruminant flocks in the region studied.
... Furthermore, in milk, the reduction of SCC due to the action of some treatments (EAF-AI, MF-AI, and MF-MA) is likely to be associated with this drop in the viral titer attributed to the antiviral effect of the extracts since the referred fractions where this effect was observed showed lower SCC. In general, high numbers of somatic cells are indicative of caprine lentivirus infection, as values > 1,000,000 cells/mL are considered evidence of subclinical mastitis in goats infected with this viral agent [70][71][72] . Thus, the reduction in somatic cells in some samples may be associated with a reduction in viral particles caused by the Meliaceae tested, which consequently led to a reduction in viral multiplication. ...
This study aimed to evaluate, in vitro, the use of leaf extracts of Azadirachta indica (A. indica) and Melia azedarach (M. azedarach) as antivirals against caprine lentivirus (CLV) in colostrum and milk of goat nannies. These were collected from eight individuals and infected with the standard strain of CLV. Samples were then subdivided into aliquots and treated with 150 µg/mL of crude extract, and with ethyl acetate and methanol fractions for 30, 60, and 90 min. Next, somatic cells from colostrum and milk were co-cultured with cells from the ovine third eyelid. After this step, viral titers of the supernatants collected from treatments with greater efficacy in co-culture were assessed. The organic ethyl acetate fractions of both plants at 90 min possibly inhibited the viral activity of CLV by up to a thousandfold in colostrum. In milk, this inhibition was up to 800 times for the respective Meliaceae. In conclusion, the ethanolic fraction of ethyl acetate from both plants demonstrated efficacy against CLV in samples from colostrum and milk when subjected to treatment, which was more effective in colostrum.
... Destas, 60% (12/20) apresentam animais com anticorpos anti-LVPR. Estudos realizados por (Pisoni et al., 2007, Alves & Pinheiro, 1997, Martínez-Navalón et al., 2013 tem demonstrado as características e possibilidades de transmissão inter espécies dos LVPR. Gomez-Lucia et al. (2013) descreve ainda a identificação de novos subtipos de LVPR e subsequente infecção cruzada inter espécies, inclusive com adaptações à animais selvagens. ...
This study aimed to evaluate the sanitary and epidemiological profiles of small ruminant lentiviruses (LVPR) from Meso West Maranhense in Imperatriz Microregion, Maranhão, Brazil. Questionnaires were applied in 57 rural properties of this region, in a total of 14 Municipalities. Beside that, 710 blood samples were collected for serologic testing. The results showed that sanitary conditions are poor and the most frequent disease were: myiasis (78.9%), caseous lymphadenitis (59.6%), foot pad dermatitis (47.4%), abortion (43.90%), mastitis (31.6 %). Serologic testing revealed that the general prevalence of lentiviruses was 7.5% (53/710) did not differ from each other: 7.5% (39/481) of sheep and 7.4% (14/176 ) goats. Regarding the municipalities it was observed that 12 of the 14 municipalities assessed presented positive animals for LVPR, characterizing the circulating viruses in this one. Among seven of these Municipalities the prevalence ranged from 8% to 15%.
... Las infecciones por SRLV tienen distribución mundial (7) y están asociadas a pérdidas económicas importantes (15,16) . En México, la presencia serológica del SRLV en caprinos de México se reportó en el año 1985 (17) y el aislamiento del virus en 1999 (18) . ...
Se realizó un estudio transversal con el propósito de determinar los factores de riesgo asociados a la frecuencia serológica de Lentivirus de los pequeños rumiantes (LvPR) en ovinos y caprinos del noreste de México. De 128 rebaños, 71 de caprinos, 32 de ovinos y 25 mixtos (caprinos + ovinos), se recolectaron 768 sueros individuales de animales ≥1 año de edad. De cada rebaño 4 a 5 muestras de suero fueron mezcladas y analizadas por ELISA para identificar anticuerpos contra la glucoproteína 135 del LvPR. Las muestras se obtuvieron de animales seleccionados al azar en los años 2019 y 2020. Se aplicó un cuestionario a los productores y los datos se analizaron para determinar los factores de riesgo asociados a la seropositividad del rebaño mediante regresión logística. La proporción de rebaños seropositivos en general fue estimada en 50.6 %. Acorde al tipo de rebaño la seropositividad en rebaños caprinos fue de 62.0 %, en ovinos de 25.4 % y de 50.2 % en rebaños mixtos. Los factores de riesgo asociados a la presencia de anticuerpos contra el LvPR fueron presencia de animales con artritis, asistencia veterinaria, reutilizar agujas, alteraciones nerviosas, bajo índice de preñez, tipo de rebaño y mastitis. La frecuencia serológica indica una alta endemicidad del LvPR en rebaños de pequeños rumiantes del noreste de México.
... The results of this study highlight how fear of humans negatively affects the productivity of goats, as fostered by [18]. However, the quality of HAR did not affect goat milk composition (e.g., content of fat or protein; [19]), probably due the chemical stability of goat milk that is only altered during diseases (e.g., [20,21]). Considering other studies on the effects of HAR on goats' productive performance, heavier weight gains were recorded in response to a greater possibility of contact with humans in feral goats kept in captivity [22]. ...
There is consensus that the quality of the human–animal relationship (HAR) is relevant to guarantee appropriate levels of animal welfare. Given the impact that HAR may have on both goats and human beings, the aim of the present review is to elucidate: (1) how humans and goats communicate; (2) which are the factors affecting human–goat interactions; (3) how we can measure the quality of this relationship. The systematic review led to the selection of 58 relevant articles. Effective human–goat communication takes place by means of visual, tactile and auditory stimuli and, to a less extent, via olfactory and gustative stimuli. Goats have well-developed socio-cognitive abilities and rely on humans to get relevant information. A deep knowledge of goats’ communication means and socio-cognitive abilities may greatly help improving the human–goat relationship. Management practices (e.g., rearing methods, amount and quality of interactions), as well as genetic selection for suitable individual traits, may contribute to improving HAR. Several measures to assess the quality of HAR have been validated, including avoidance in the pen and at the feeding rack and latency to first contact. Finally, farmers’ attitudes and empathy with goats, as well as their motivation to work with animals, should be improved through appropriate training.
... Management of colostrum (such as heat treatment) may also affect its quality. One disease, caprine arthritis encephalitis (CAE), an infection caused by a lentivirus, causes economic losses since goats may have a shorter lactation period, lower milk yield, and altered milk composition [10]. The clinical signs include weight loss, chronic arthritis, encephalomyelitis, and mastitis [11]. ...
Background and aim:
Immunoglobulin G (IgG) concentration is high in goat colostrum, particularly in the first few hours after parturition, and this is important for the kid's immunity and growth. IgG levels vary depending on several factors, including breed, disease status, colostrum management, handling, and collection time postpartum. A handheld optical refractometer, an affordable instrument that is simple to use in the field, is used widely in dairy farms to measure total solids. However, it can also be applied to estimate colostrum IgG content on the basis of comparison with standard measurement methods, usually radial immunodiffusion. Studies comparing %Brix values in relation to IgG concentration measured using enzyme-linked immunosorbent assay (ELISA) in goats are limited. The present study aimed to evaluate the use of a handheld optical Brix refractometer for the measurement of IgG concentration in goat colostrum, compare results with those using ELISA, and estimate the %Brix cutoff value equating to low-quality colostrum.
Materials and methods:
Colostrum samples were collected on day 0 from 21 goats (nine Black Bengal, six Saanen, and six of their crossbred offspring) and were frozen. Subsequently, they were analyzed for IgG concentration using a goat-specific ELISA test and Brix percentage using a handheld refractometer. The optimum %Brix cutoff value for the evaluation of colostrum quality was evaluated.
Results:
The mean IgG concentration and %Brix in colostrum were 10.60±0.64 mg/mL and 25.0±0.9, respectively. There was a significant (p<0.01) correlation between %Brix and IgG concentration. For an IgG concentration of 6.9 mg/dL, the cutoff value for %Brix was 18.5, equating to high specificity (100%) but low sensitivity (50%). A higher %Brix cutoff value of 21.5 showed high specificity (95%) and high sensitivity (100%).
Conclusion:
A Brix refractometer can be used to estimate goat colostrum quality with a proposed %Brix cutoff value of <18.5%-21.5% for poor-quality colostrum.
... Infections with SRLV, which are spread worldwide, cause multi-organ failure usually over a long period of time and can lead to severe diseases such as pneumonia, mastitis, arthritis, wasting, and encephalitis [2]. Moreover, they contribute to economic losses in small ruminant production and affect animal welfare deterioration [3,4]. ...
Small ruminant lentiviruses (SRLV) are economically important viral pathogens of sheep and goats. SRLV infection may interfere in the innate and adaptive immunity of the host, and genes associated with resistance or susceptibility to infection with SRLV have not been fully recognized. The presence of animals with relatively high and low proviral load suggests that some host factors are involved in the control of virus replication. To better understand the role of the genes involved in the host response to SRLV infection, RNA sequencing (RNA-seq) method was used to compare whole gene expression profiles in goats carrying both a high (HPL) and low (LPL) proviral load of SRLV and uninfected animals. Data enabled the identification of 1130 significant differentially expressed genes (DEGs) between control and LPL groups: 411 between control and HPL groups and 1434 DEGs between HPL and LPL groups. DEGs detected between the control group and groups with a proviral load were found to be significantly enriched in several gene ontology (GO) terms, including an integral component of membrane, extracellular region, response to growth factor, inflammatory and innate immune response, transmembrane signaling receptor activity, myeloid differentiation primary response gene 88 (MyD88)-dependent toll-like receptor signaling pathway as well as regulation of cytokine secretion. Our results also demonstrated significant deregulation of selected pathways in response to viral infection. The presence of SRLV proviral load in blood resulted in the modification of gene expression belonging to the toll-like receptor signaling pathway, the tumor necrosis factor (TNF) signaling pathway, the cytokine-cytokine receptor interaction, the phagosome, the Ras signaling pathway, the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) (PI3K-Akt) signaling pathway and rheumatoid arthritis. It is worth mentioning that the most predominant in all pathways were genes represented by toll-like receptors, tubulins, growth factors as well as interferon gamma receptors. DEGs detected between LPL and HPL groups were found to have significantly enriched regulation of signaling receptor activity, the response to toxic substances, nicotinamide adenine dinucleotide (NADH) dehydrogenase complex assembly, cytokine production, vesicle, and vacuole organization. In turn, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway tool classified DEGs that enrich molecular processes such as B and T-cell receptor signaling pathways, natural killer cell-mediated cytotoxicity, Fc gamma R-mediated phagocytosis, toll-like receptor signaling pathways, TNF, mammalian target of rapamycin (mTOR) signaling and forkhead box O (Foxo) signaling pathways, etc. Our data indicate that changes in SRLV proviral load induced altered expression of genes related to different biological processes such as immune response, inflammation, cell locomotion, and cytokine production. These findings provide significant insights into defense mechanisms against SRLV infection. Furthermore, these data can be useful to develop strategies against SRLV infection by selection of animals with reduced SRLV proviral concentration that may lead to a reduction in the spread of the virus.
... Research shows that among the losses caused by this disease, seropositive animals exhibit a decline in milk production and quality, with an increase in somatic cell counts (Leitner et al., 2010;Martínez-Navalón et al., 2013). However, conflicting results such as those published by Greenwood (1995); Nord and Adnoy (1997); Turin et al. (2005) and Kaba, Strzałkowska, Jóźwik, Krzyżewski and Bagnicka (2012) have shown that in the first lactation, there is no significant difference in milk production or quality between animals seropositive and seronegative for CAE. ...
The aim of this study was to examine the influence of caprine arthritis encephalitis (CAE) on the production of milk and its components (protein, fat and total solids) along the lactation curve of primiparous goats. The study was developed using a database from the years 2014 to 2018. Sixty-one animals were subjected to the serological test for CAE, whose result indicated that 42 were seropositive and 19 seronegative, and milk production and quality data were compiled. To adjust the curve for production of milk, fat, protein and total solids during lactation, the following nonlinear model developed by Wood (1967) was used: Y = atb e-ct, where Y represents the observations of milk, fat, protein or total solid production at time t; a is the parameter associated with the initial production; b is the parameter associated with the rate of rise in production until the peak; c is the parameter associated with the rate of decline of the lactation curve; and is the representative time of the day in milk. The parameters were compared by the confidence interval considering 95% probability. Peak production was calculated using the following formula: a(b/c)b e-b. There was no statistical difference (p > 0.05) between seropositive and seronegative primiparous goats for initial production and the rates of rise and decline of the parameters of milk, fat, protein and total solid production. However, at their peak, these variables were 26, 27, 23 and 23% higher, respectively, in the seronegative goats than in their seropositive counterparts. In conclusion, CAE does not affect milk production or the production of fat, protein and total solids along the lactation curve, but seropositive goats produce less milk and respective components at the peak of the lactation curve than seronegative goats.
... Its wide prevalence makes it one of the most significant causes of decreased dairy goat production among small ruminants [10]. However, contradictory results have been obtained regarding milk yield and composition among infected goats [13][14][15][16]. ...
The present study examines the effects of natural infection by small ruminant lentivirus (SRLV) in the two most common goat breeds in Poland, i.e., Polish white improved and polish fawn improved. It focuses on biomarkers of oxidative stress, oxidatively modified proteins and antioxidant defenses, ceruloplasmin level as an acute phase protein, and the activities of antioxidant enzymes in the goat serum. It was conducted on 24 goats divided into two equal groups: one SRLV-seropositive (SRLV-SP) and another SRLV-seronegative (SRLV-SN). Both groups were identical in terms of breed and parity. Despite infection, the SRLV-SP goats demonstrated no symptoms of caprine arthritis-encephalitis. In addition, the SRLV-SP goats did not reveal pronounced dysfunctions in oxidative stress biomarkers in the serum compared to the SRLV-SN animals. However, both groups demonstrated elevated levels of the aldehydic and ketonic derivatives of oxidatively modified proteins during the lactation period. In addition, both groups retained a high total antioxidant capacity in serum despite the decrease of enzyme antioxidant defenses throughout the 200-day lactation period.
... In goats the infection leads to progressive arthritis and wasting, with rare udder and lung involvement, known as caprine arthritis-encephalitis (CAE). Moreover, SRLV infection is known to have a negative impact on goats' productivity (Kaba et al., 2012;Martínez-Navalón et al., 2013;Nowicka et al., 2015), although its true extent is still controversial. ...
Caprine arthritis-encephalitis (CAE) caused by small ruminant lentivirus (SRLV) infection is one of the most widespread and devastating diseases of goats. Serological methods, mainly immunoenzymatic assays (ELISA), are the mainstay of CAE diagnostics. Even though blood is still the most commonly tested material, animal welfare issues and increasing costs of veterinary service prompt the development of serological methods based on milk testing. Several different types of ELISAs for CAE are available on the market. All of them perform well on serum, however their diagnostic accuracy for testing milk has not been so far compared. Therefore, we carried out the study in 5 dairy goat herds in Poland whose previous epidemiological situation regarding CAE was known. Paired serum and milk samples were collected from all adult females (n = 420) and tested with 3 commercial ELISAs – indirect ELISA based on the whole-virus antigen (wELISA), indirect ELISA based on the recombined transmembrane and capsid protein (TM/CA-ELISA), and competitive ELISA based on the surface glycoprotein (SU-ELISA). Milk was tested as lactoserum at dilution of 1/2 in wELISA and TM/CA-ELISA, and undiluted in SU-ELISA. The true status of goats was based on the composite reference standard comprising the results of all three ELISAs done on serum and the true prevalence of SRLV infection in the herd of origin. 243 (57.9%) goats were classified as truly positive and 177 (42.1%) goats as truly negative. Diagnostic accuracy was evaluated using the area under the ROC curve (AUROC) as well as sensitivity (Se) and specificity (Sp) for a range of cut-off values. AUROC was 98.8% (CI 95%: 97.5%, 100%) for wELISA, 97.9% (CI 95%: 96.5%, 99.2%) for TM/CA-ELISA, and 91.7% (CI 95%: 88.9%, 94.5%) for SU-ELISA. At the cut-off values recommended by the manufacturers both indirect ELISAs were highly sensitive (89.3% and 91.4%, respectively) and highly specific (98.3% and 95.5%, respectively), whereas SU-ELISA had only moderate Se (71.2%) at comparably high Sp (96.6%). Nevertheless, the optimal cut-off values were lower than those recommended by manufacturers for serum – sample-to-positive control serum ratio (S/P%) of 10% for wELISA, S/P% of 80% for TM/CA-ELISA, and percentage inhibition of 23% for SU-ELISA. Concluding, the study shows that wELISA and TM/CA-ELISA may be interchangeably used for testing individual goat milk samples for SRLV infection. Diagnostic sensitivity and specificity of these ELISAs appear not to be lower on milk than on serum. SU-ELISA is considerably less sensitive on milk samples than indirect ELISAs.
... Регресійні моделі підтвердили асоціацію між серопозитивністю кіз і зменшенням виробництва молока. Відзначалося, що серопозитивні кози мають на 10 % меншу продуктивність молока порівняно із серонегативними козами (Martinez-Navlon et al., 2007). ...
У науковій монографії викладено сучасне розуміння поняття «персистування
вірусів» і формування повільних, хронічних і латентних інфекцій у сільськогосподарських і диких тварин. Розкриті основні механізми персистування вірусів під час
повільних інфекційних захворювань. Автори, ґрунтуючись на наукових працях (вірусологів, епізоотологів й епідеміологів), виводять загальні закономірності, причини
й передумови виникнення повільних інфекцій, розкривають сучасні відомості про
збудників, клінічний і патолого-анатомічний їхні прояви, епізоотологічні та епідеміологічні особливості, сучасні методи діагностики, специфічної профілактики й
заходи боротьби з найбільш актуальними (переважно зоонозними) повільними інфекціями в рамках підходу «Єдине здоров’я».
Розрахована на спеціалістів районних і обласних управлінь, лікарень ветеринарної медицини, слухачів інститутів і факультетів післядипломного навчання, викладачів та студентів факультетів ветеринарної медицини вищих навчальних аграрних закладів і широке коло практичних фахівців ветеринарної медицини.
... Caprine Arthritis Encephalitis (CAE) arthritis, lökoensefalitis ve kronik interstitial pnömoni ile karakterize keçilerin viral bir hastalığı olarak bilinmektedir (32). CAE enfeksiyonu kilo kaybı, düşük doğum ağırlığı, hayvan ticaretindeki kısıtlamalar, süt veriminde düşme ve mutlak ölümlerle sonuçlandığından keçi yetiştiriciliğinde büyük ekonomik kayıplara neden olmaktadır (24,30). ...
Bu çalışmada, Burdur ilinde halk elinde bulunan saf ırk özelliği taşıyan dişi Honamlı keçilerinde Caprine Arthritis Encephalitis Virus (CAEV) enfeksiyonunun varlığı araştırıldı. Bu amaçla 1 yaş üstü, dişi ve sağlıklı görünüme sahip 187 (yüz seksen yedi) adet keçiden kan örneklemesi yapıldı. Çalışmada Honamlı ırkı dişi keçilerin yerleşim yerlerine ve yaşlarına göre seroprevalanslarının ve enfeksiyona karşı hassasiyetlerinin ortaya konması amaçlandı. Örnekleme yapılan ağıl koşulları; Duvar, Çatı ve Zemin, Yemlik ve Suluk, Ortamın İlaçlanması, Ayrı Bölme (Keçi, Teke ve Oğlak), Karışık/Ortak Emzirme olarak 5 kriter altında değerlendirildi. Araştırmada, 5 yerleşim yerinden ve 10 ağıldan toplanan 187 keçi kan serumu, Enzyme Linked Immunosorbent Assay (ELISA) testi uygulanarak CAEV antikorları yönünden kontrol edildi. Test edilen 187 adet keçi kan serumunun 3 (%1.60) adedi seropozitif olarak belirlendi. Yerleşim yerlerine göre seropozitiflik oranları %0-5 arasında tespit edildi. Yaşa göre kan numunelerinde ELISA testi ile 2 yaş grubunda 1 (%1.79), 4 ve üstü yaş grubunda 2 (%8.70) seropozitiflik tespit edildi. 4 farklı yaş grubu arasında seropozitiflik açısından yapılan karşılaştırmada istatistiki önem bulundu (p=0.025, p<0.05). Ağıl durum değerlendirmesinde seropozitiflik bulunan ağıllarda; Duvar, Çatı ve Zemin, Yemlik ve Suluk’ların “Kötü”, Ortamın İlaçlanması, Ayrı Bölme (Keçi, Teke ve Oğlak)’lerin “Yok”, Karışık/Ortak Emzirme’nin “Var” olduğu görüldü.
... Lentivirosis of small ruminants (LVPR) are infectious diseases caused by Lentiviruses (5) , which result in economic losses in sheep farming and slow the growth of the production chain (6) , however, due to their chronic evolution, they may go unnoticed by the producer (7) . The disease triggers inflammatory, degenerative and immune-mediated lesions in the neurological, respiratory, mammary gland and joints (8,9,10) of the animals. Lentiviruses are classified into five phylogenetic groups and their viral prototypes for sheep and goats are the maedi-visna virus (MVV) and the caprine arthritis encephalitis virus (CAEV), respectively, although the possibility of interspecies transmission has already been demonstrated (11, 12.13). ...
Lentivirosis of small ruminants (LVPR) are chronic and degenerative infectious diseases, caused by Lentivirus, associated with numerous losses such as: drop in meat and milk production, predisposition to secondary infections, expenses with veterinary assistance and, even, early disposal of animals. In the northern region of Brazil, the epidemiological situation is poorly understood. Thus, this study aimed to determine the seropositivity of sheep for Lentivirus in Porto Acre city, Western Amazon, Brazil. 122 blood samples from sheep were collected and as a diagnostic method, agarose gel immunodiffusion was used, using the p28 protein of the capsid as antigen. The seropositivity of the sheep to the test was 8.2% (10/122). In 80% (4/5) of the investigated properties, the presence of seropositive animals was detected. It is worth noting that the acquisition of small ruminants from other states likely represented a risk to sheep health in the municipality of Porto Acre, Western Amazon, Brazil. It is concluded that there is a need for more systematic investigations on the prevalence of LVPR in the state of Acre.
Keywords: Lentivirus; Small ruminants; Amazon region; Serology.
... Quantification of productive losses due to SRLV infection remains controversial, while some studies claim for a role of SRLV infection in decreasing quantity and quality of animal productions in both dairy and meat farms (12)(13)(14), others have revealed no differences between seronegative and seropositive animals (15)(16)(17)(18)(19). Slow disease development is a key feature of lentiviral infections and is the main cause of the underestimated losses in terms of animal production. However, differences in the production system, breed resistance, flock management, and parameters evaluated (20) may also explain the different associations between SRLV infection and productive traits. ...
Small ruminant lentiviruses (SRLVs) are endemic in most areas of Europe, causing a chronic infection and a multisystemic disease affecting the udder, carpal joints, lungs, and central nervous system. Due to the lack of treatments and protective vaccination strategies, infection control is focused on the identification of infected animals through serological or molecular techniques. However, antigenic and genetic heterogeneity of SRLVs represent a clear drawback for diagnosis. Infected animals may present lower animal production parameters such as birth weight or milk production and quality, depending on productive systems considered and, likely, to the diagnostic method applied. In this study, four sheep flocks dedicated to dairy or meat production were evaluated using three different ELISA and two PCR strategies to classify animal population according to SRLV infection status. Productive parameters were recorded along one whole lactation or reproductive period and compared between positive and negative animals. SRLV was present in 19% of the total population, being unequally distributed in the different flocks. Less than half of the infected animals were detected by a single diagnostic method, highlighting the importance of combining different diagnostic techniques. Statistical analysis employing animal classification using all the diagnostic methods associated lambing size, lamb weight at birth, and daily weight gain with SRLV infection status in meat flocks. Milk production, somatic cell count, fat, and protein content in the milk were associated with SRLV infection in dairy flocks, to a greater extent in the flock showing higher seroprevalence. A multi-platform SRLV diagnostic strategy was useful for ensuring correct animal classification, thus validating downstream studies investigating production traits.
... Exploitation of active surveillance programs and quantification of the consequences of SRLVs' infection on production [93], health and welfare traits are critical endeavors to determine the overall impact of the disease on the sustainability and resilience of the farms. For this reason, large-scale longitudinal and cohort studies are necessary to collect data for the determination of the most appropriate prediction models estimating the cost of the disease (production losses, involuntary culling/increased replacement rate, predisposition to other diseases and control measures), which remains unknown. ...
Maedi-visna (MV) in sheep is caused by maedi-visna virus (MVV), a small ruminant lentivirus (SRLV) that causes chronic infection and inflammatory lesions in infected animals. Pneumonia and mastitis are its predominant clinical manifestations, and the tissues infected by MVV are mainly the lungs, the mammary gland, the nervous system and the joints. MV has a worldwide distribution with distinct MVV transmission patterns depending on circulating strains and regionally applied control/eradication schemes. Nevertheless, the prevalence rate of MV universally increases. Currently, gaps in understanding the epizootiology of MV, the continuous mutation of existing and the emergence of new small ruminant lentiviruses (SRLVs) strains, lack of an effective detection protocol and the inefficiency of currently applied preventive measures render elimination of MV an unrealistic target. Therefore, modifications on the existing MV surveillance and control schemes on an evidentiary basis are necessary. Updated control schemes require the development of diagnostic protocols for the early and definitive diagnosis of MVV infections. The objectives of this review are to summarize the current knowledge in the epizootiology and control of MV in dairy sheep, to describe the research framework and to cover existing gaps in understanding future challenges regarding MV.
... While several studies have investigated the link between SRLV infection and milk yield or milk quality [6][7][8], so far only one has described its influence on the growth of kids [9]. It revealed that growth rate of kids from seropositive does was significantly lower both before and after weaning at the age of 3 months. ...
A longitudinal observational study was carried out to evaluate the influence of prenatal exposure to small ruminant lentivirus(SRLV)-infected does on the body weight (BWT) of young kids. The study was carried out in years 2001–2017 in the research dairy goat herd. Goats in the herd were regularly serologically tested and individuals showing clinical signs of caprine arthritis-encephalitis (CAE) were promptly culled. As a result all goats enrolled in the study were asymptomatic. Moreover, kids were weaned immediately after birth, fed on bovine colostrum and kept in strict separation from mothers to prevent SRLV lactogenic transmission. Kids were weighed immediately after birth, and then 1–3 times within the first 3 months of life. In total 620 goat kids were weighed at least once, excluding weighing at birth, providing 992 BWT records. The mixed linear model including four variables fitted as random effects (doe, kid, the year of kid’s birth and the exact age of a kid at weighing) and four potential confounders fitted as fixed effects (parity, kid’s sex, litter size and birth body weight) was developed and showed that BWT was not significantly associated with SRLV serological status of a doe, regardless of the time for which does had been infected before the delivery of the kid (p = 0.242). This study provides strong evidence that kids born to SRLV-infected does grow equally well as kids from uninfected does, provided that the lactogenic viral transmission is prevented by maintaining strict separation between the offspring and mothers. This observation is important for choosing the most optimal strategy of CAE control in a goat herd.
... These viruses cause multisystem chronic inflammatory and degenerative diseases clinically characterized by pneumonia, wasting, arthritis, encephalitis, and mastitis. SRLV are widespread throughout the world, causing damaging economic effects in the small ruminant industry due to increased mortality and reduced milk production (Martínez-Navalón et al., 2013). ...
Small ruminant lentiviruses (SRLV) are widespread amongst domesticated sheep and goats worldwide. Infection of wild ruminants in close contact with affected domesticated small ruminants has been proposed as an actor in SRLV epidemiology, but studies are limited. The aim of this study was to estimate the apparent (AP) and estimated prevalence (EP) of exposure to SRLV infection in wild ruminants from Poland. Samples originating from 198 free-living cervids comprising 142 European red deer and 56 roe deer were serologically tested using a multi-epitope recombinant antigen ELISA representing subtypes A1, A13, B1, and B2 of SRLV and a commercial ELISA test. The estimated prevalence of SRLV infection was estimated using the Bayesian approach with models that adjusted for the misclassification of animals because of a small population and lack of sampling method, the imperfect performance of the ELISAs and because sera of different species were tested. The calculated estimated prevalence ranged from 5.3 % (95 % CI 0.3, 12.5) to 24.6 % (95 % CI 3.3, 38.5) for the ELISA with multi-epitope antigens while estimated prevalence using the commercial ELISA was 2.5 % (95 % CI 0.2, 6.6). These results may suggest the existence of a new SRLV reservoir in Poland and highlight the importance of surveilling and controlling SRLV infection in domestic and wild ruminants sharing pasture areas.
... The most prominent clinical signs of CAE are arthritis and chronic wasting. They deteriorate animals' condition and welfare, decreasing their productivity and necessitating culling of diseased goats [3]. However, clinical signs develop after several years of infection and only in less than a half of infected goats [4,5]. ...
A longitudinal study was carried out to investigate the influence of two different rearing systems of young kids on their development to sexual maturity. Kids born to small ruminant lentiviruses-infected (SRLV) female goats were split into two groups: the immediately-after-birth weaned group and the unweaned group. Kids’ body weight (BWT) was measured before the first consumption of colostrum, and then at the age of one week, and one, two, four, and seven months. The relationship between the rearing system and BWT at each age was investigated using mixed linear models adjusted for potential confounders. The mean BWT of kids of the immediately-after-birth weaned group was significantly lower at the age of one week, one month, and two months, and then the difference became insignificant. The mean daily body weight gain (DWG) was significantly lower in the immediately-after-birth weaned group during the whole first month of life, but then DWG in both groups became equal. Crude mortality rate did not differ significantly between groups. This study shows that weaning kids immediately after birth does not appear to have any negative impact on kids’ development except transient growth retardation, which is fully compensated until they reach sexual maturity.
... Both diseases develop slowly and even though they may eventually progress into severe clinical conditions including interstitial pneumonia, joint inflammation, indurative mastitis, emaciation, and central nervous system dysfunction, it rarely happens in animals less than 2-3 year-old (Smith and Sherman, 2009). However, it has been shown that even subclinical lentiviral infection negatively affects milk and cheese production and quality in goats (Kaba et al., 2012;Martínez-Navalón et al., 2013;Nowicka et al., 2015). ...
A longitudinal study was conducted in a single dairy goat herd to investigate the relationship between subclinical small ruminant lentivirus (SRLV) infection in does and litter size (LS) or birth body weight of kids (BW). Each year kids born to seropositive and seronegative does were weighed before the first consumption of colostrum. LS and BW of each kid were recorded. BW was significantly negatively linked to LS (p = 0.006) – singletons weighed (mean ± SD) 4.20 ± 0.67 kg, twins – 3.75 ± 0.62 kg, and triplets and quadruplets – 3.38 ± 0.47 kg. Male kids were significantly heavier than female kids in twin litters (3.97 ± 0.53 kg vs. 3.52 ± 0.60 kg; p < 0.001) and triplet or quadruplet litters (3.62 ± 0.40 kg vs. 3.17 ± 0.43 kg; p < 0.001). However, BW of male and female kids from singleton litters did not differ (4.31 ± 0.71 kg vs. 4.07 ± 0.65 kg; p = 0.154). Then, two mixed models were developed to assess the relationship between LS (mixed Poisson log linear regression model) or BW (mixed linear model) and SRLV infection in the doe, controlling for potential confounders such as the effect of an individual doe, year in which the parturition took place, parity and kid's sex. Neither LS nor BW proved to be significantly associated with SRLV infection (p = 0.788 and p = 0.214, respectively). On this basis it was concluded that LS and BW were not affected by the subclinical SRLV infection of a doe.
... It is evident that the diffusion of SRLV infection in the herd can significantly affect milk production. Overall, milk production is estimated to decrease by 10% in affected herds (Martínez-Navalón et al., 2013). Occasionally, goats with serologic evidence of CAEV infection may develop chronic interstitial pneumonia and progressive dyspnea (Barrero Domínguez et al., 2017). ...
Small ruminant lentiviruses (SRLVs) can drastically affect milk production in goat flocks and only an early detection can control and prevent their spread. Since SRLVs are responsible for persistent infections, antibody screening is the most valuable tool to identify infected animals. ELISA is recommended as the election test both for its sensitivity and for its ability to detect low antibody titers, thus identifying infected animals earlier than agar gel immunodiffusion (AGID). In the present study, an investigation was conducted to assess the SRLV seroprevalence in goat flocks in southern Italy and a transversal comparative study was carried out through the analysis of the possible risk factors influencing SRLV spread. A total of 4800 sera from 1060 flocks were analyzed and overall seroprevalences of 18,64% and 51,69% at animal and herd levels, respectively, were observed. Both the region and the herd production systems were able to affect seroprevalence, differently from the herd size, probably because the mean number of goats per herd is low and the semi-intensive management is similar regardless of the dimensional class of each herd. In particular, meat producing herds showed the higher seroprevalence, as a result of the poor sanitation and low animal monitoring in comparison to milk producing herds, where animals are managed twice daily and the relationship between dams and kids is checked to guarantee an adequate quantitative/qualitative milk yield. In the absence of vaccines or effective treatments, health preventive management and seroepidemiological investigations are the only successful approach to restrict SRLV spread as observed in countries were official/voluntary control programs are carried out.
... Caprine arthritis-encephalitis (CAE), caused by a small ruminant lentivirus (SRLV) infection, is a widespread transmissible disease of goats with a considerable negative impact on dairy production [1,2,3]. The disease emerged in Poland in early nineties of the 20 th century and has become widespread in Polish goat population over the next decade from roughly 30% in 1996 to 70% in 2007 [4]. ...
Small ruminant lentivirus (SRLV) infection manifests itself mainly with chronic progressive arthritis affecting mainly carpal joints. The data from serological and questionnaire surveys were retrospectively analyzed to determine how the dissemination of SRLV infection in the herd influenced farmer’s subjective opinion on the occurrence of swelling of carpal joints (considered as a proxy of arthritis). Between 1996 and 2017 153 different Polish dairy goat herds counting at least 20 adult goats were serologically screened for CAE and their owners were asked about their opinion on the occurrence of arthritis (never, rarely, often). Of them 73 SRLV-seropositive herds, in which true seroprevalence had been estimated, were included in the analysis. The ordinal logistic regression model was developed to determine the relationship between the true within-herd seroprevalence and the probability that the farmer would observe arthritis in the herd never, rarely or often. True within-herd seroprevalence ranged from 0.2% to 100% with the median of 34.6%. Farmers declared not to have observed arthritis in 40 (54.8%) herds, to have seen it rarely in 9 (12.3%) of herds, and to have observed it often in 24 (32.9%) of herds. The model proved that the probability of observing goats with carpal arthritis in the herd was significantly linked to the true within-herd seroprevalence (OR = 1.058, CI 95% from 1.037 to 1.078; p<0.001), but this relationship was not linear and SRLV infection proved to remain unapparent to farmers even when a considerable part of the herd had already become infected. Concluding, the study shows that when the farmer realizes that goats in the herd suffer from arthritis, SRLV infection is almost certainly already widespread in the herd.
... One of the most important productive impacts of SRLV disease is due to the premature removal of diseased animals because of low milk production and quality with consequent economic losses in the milk-related and lamb/kids-related industry [11][12][13]. Due to the significant economic impact of diseases, VM and CAE are included in the OIE List and specific control and eradication programs are carried out in many countries [14,15]. Availability of sensitive and specific diagnostic tests is of great importance for a correct discrimination between infected and non-infected animals. ...
Small Ruminant Lentiviruses (SRLVs) are widespread in many countries and cause economically relevant, slow, and persistent diseases in sheep and goats. Monitoring the genetic diversity of SRLVs is useful to improve the diagnostic tools used in the eradication programs. In this study, SRLVs detected in Spanish Assaf sheep with different grades of lymphoproliferative mastitis were sequenced. Genetic characterization showed that most samples belonged to type A and were closer to Spanish SRLV isolates previously classified as A2/A3. Four samples belonged to subtype B2 and showed higher homology with Italian B2 strains than with Spanish B2 isolates. Amino acid sequences of immuno-dominant epitopes in the gag region were very conserved while more alterations were found in the LTR sequences. No significant correlations were found between grades of mastitis and alterations in the sequences although samples with similar histological features were phylogenetically closer to each other. Broader genetic characterization surveys in samples with different grades of SRLV-lesions are required for evaluating potential correlations between SRLV sequences and the severity of diseases.
... Todavia, em muitos casos, essa doença pode ser assintomática e os animais portadores do vírus se tornam fonte de infecção (Gregory et al., 2011). Martínez-Navalón et al. (2013) observaram que, em estudo retrospectivo realizado com 4543 cabras de 22 rebanhos leiteiros, animais soropositivos tinham lactações mais curtas e menor produção leiteira em comparação aos animais soronegativos. O leite apresentava menor teor de gordura, lactose e sólidos totais e maior contagem de células somáticas. ...
The aim of this study was to evaluate the periodic use of more sensitive diagnostic tests associated to management practices for the effective control of caprine arthritis-encephalitis (CAE). We carried out eight blood samples in does and bucks. From the first to the seventh analysis, the samples were quarterly, using Agarose Gel Immunodiffusion (AGID), Enzyme linked immunosorbent assay (i-ELISA) and Western Blot (WB) tests. The eighth collection was made six months after the seventh, using the WB and Polymerase Chain Reaction (PCR). The prevalence of CAE was 6.8%, 14.9% and 39.2% in the AGID, i- ELISA and WB respectively. The last analysis detected 0.9% of animals positive by WB and 10.8% by PCR. Although they do not eradicate CAE, steps taken together with the periodic use of serological tests and the combination with PCR were important to significantly reduce positive animals in the herd.
O objetivo deste trabalho foi avaliar a utilização periódica de testes de diagnóstico mais sensíveis aliados àrs práticas de manejo, visando ao controle eficaz da artrite encefalite caprina (CAE). Foram realizadas oito coletas de sangue em matrizes e reprodutores. Da primeira à sétima análise, as coletas foram quadrimestrais, utilizando-se os testes de imunodifusão em gel de agarose (IDGA), ensaio imunoenzimático indireto (ELISA-i) e Western Blot (WB). A oitava coleta aconteceu seis meses após a sétima, utilizando-se o WB e a reação em cadeia de polimerase (PCR). A prevalência da CAE foi de 6,8%, 14,9% e 39,2% no IDGA, ELISA-i e WB, respectivamente. Na última análise, foram detectados 0,9% de animais positivos pelo WB e 10,8% pela PCR. Apesar de não erradicarem a CAE, as medidas adotadas, aliadas à utilização periódica dos testes sorológicos e à combinação com a PCR, foram importantes para reduzir significativamente os animais soropositivos no rebanho.
... Caprine arthritis encephalitis (CAE) may decrease the duration of lactation, milk production, and levels of fat and protein in milk produced by infected goats (CARNEIRO, 2011). MARTÍNEZ-NAVALÓN et al. (2013) found that seropositive animals had shorter lactation periods and produced less milk. In addition, such milk presented lower levels of fat, lactose and total solids, as well as higher somatic cell count than the milk produced by seronegative goats. ...
Caprine arthritis encephalitis causes considerable losses in goat production. The main form of the caprine arthritis encephalitis virus transmission is through the ingestion of colostrum or milk from infected females. However, some transmissions cannot be explained in this manner. Therefore, this study aimed to evaluate transplacental transmission of caprine arthritis encephalitis virus. Blood samples were collected from 283 newborn kids of Anglo-Nubian and Saanen breeds born from seropositive and seronegative goats. Samples were collected immediately after birth and analyzed with agarose gel immunodiffusion and western blot. All samples were negative in the agarose gel immunodiffusion. However, the western blot test demonstrated that four kids were born positive for caprine arthritis encephalitis virus. This result indicates that although in a low frequency (1.4%), there is a possibility of transplacental transmission of small ruminant lentivirus.
... Caprine arthritis encephalitis has a negative impact on several performance parameters, leading to economic losses. [34][35][36] Clinical signs in SRLV-infected animals include a decrease in milk productivity and milk quality, loss of weight, and premature death; Paper furthermore, animals at advanced stages of the disease present a significantly reduced bodyweight at slaughter, and therefore may not be suitable for consumption. 15 37 38 Along with poor animal welfare and environmental protection, 15 these economic factors have contributed to the growing demand for control and eradication programmes to be undertaken by countries around the world. ...
Small ruminant lentivirus infections in goats affect both production and animal welfare. This represents a threat to the qualitative and quantitative growth of goat farming, recently observed in mountainous regions such as the Autonomous Province of Bolzano-South Tyrol (Italy). To monitor and eradicate the caprine arthritis encephalitis virus in this goat population, a compulsory eradication campaign was launched, based on a strict census of small ruminants and yearly serological testing of all animals, followed by the consequent culling of seropositive individuals. The campaign succeeded in completely eliminating cases of clinical disease in goats, while drastically reducing the seroprevalence at the herd as well as individual animal level. The serological outcome of the introduced control measures was determined using commercially available ELISA kits, demonstrating their suitability for use in this type of campaign, aimed at reducing seroprevalence as well as clinical manifestations of these infections. However, this clear success is diminished by the failure to achieve a complete eradication of these viruses. The reasons leading to the observed tailing phenomenon and the occurrence of new infections in already sanitised flocks are discussed and implementation of further measures are proposed.
... In addition, the CAEV serological status has been associated with bacterial intramammary infections (IMIs), especially in herds with a high prevalence of CAEV and bacterial IMIs (Bergonier et al., 2003;Jiménez-Granado et al., 2014). These facts would contribute, at least in part, to the worsening of production records (Martínez-Navalón et al., 2013;Jiménez-Granado et al., 2014) and to a reduced cheese yield (Nowicka et al., 2015), both of which have previously been reported for CAEV-seropositive goats. Altogether, these scenarios appear suitable for an investigation of the effects of CAEV on mammary gland immunity, which is largely dependent on phagocyte function (Souza et al., 2012a,b). ...
The exact influence of caprine arthritis encephalitis virus (CAEV) infection on blood and milk polymorphonuclear leukocytes (PMNLs) and monocyte/macrophages of goats remains unclear. Thus, the present study sought to explore the blood and milk PMNL and monocyte/macrophage functions in naturally CAEV-infected goats. The present study used 18 healthy Saanen goats that were segregated according to sera test outcomes into serologically CAEV negative (n = 8; 14 halves) and positive (n = 10; 14 halves) groups. All milk samples from mammary halves with milk bacteriologically positive outcomes, somatic cell count ≥ 2 × 10⁶ cells mL⁻¹, and abnormal secretions in the strip cup test were excluded. We evaluated the percentage of blood and milk PMNLs and monocyte/macrophages, the viability of PMNLs and monocyte/macrophages, the levels of intracellular reactive oxygen species (ROS) and the nonopsonized phagocytosis of Staphylococcus aureus and Escherichia coli by flow cytometry. In the present study, a higher percentage of milk macrophages (CD14⁺) and milk polymorphonuclear leukocytes undergoing late apoptosis or necrosis (Annexin-V⁺/Propidium iodide⁺) was observed in CAEV-infected goats; we did not find any further alterations in blood and milk PMNL and monocyte/macrophage functions. Thus, regarding our results, the goats naturally infected with CAEV did not reveal pronounced dysfunctions in blood and milk polymorphonuclear leukocytes and monocytes/macrophages.
... Finally, it should be taken into account that Spain is the third European country in goat milk production and that diseases such as CAEV are responsible for the decrease in this production. In our country few studies have been carried out on CAEV seroprevalence, and even less about risk factors, with most of them focused on other geographic areas (Contreras et al., 1998, Sánchez et al., 2001, Martínez-Navalón et al., 2013. Therefore, the present study aims to analyse the exposure to CAEV in goat flocks from southern Spain as well as the risk factors associated to the exposure to the virus. ...
The aim of the present transversal descriptive study was to determine the exposure and risk factors associated with caprine arthritis-encephalitis virus (CAEV) in southern Spain. A total of 3,312 serum samples were collected from goat belonging to three different breeds coming from 48 flocks located in different geographic areas from southern Spain. In addition, health and productive parameters were surveyed during the visit to the herds. Serum samples were analysed by INgezim Maedi Screening (Ingenasa®) ELISA kit. The total percentage of herds exposed to CAEV was 87.71% (CI95 78.42-97.00). A total of 733 goats were seropositive with overall seroprevalence of 23.22% (CI95 21.78-24.65). The intraherd seroprevalence was 20.82%±24.07. Multivariate logistic regression showed significant association between CAEV and the next variables: (i) herd size In cursive (P<0.0001; OR: 2.07; CI95: 1.73-2.50), (ii) kidding area (P<0.0020; OR: 1.38; CI95: 1.13-1.69), (iii) cleaning and disinfection program (P<0.0067; OR: 1.90; CI95: 1.43-2.53), (iv) natural mating In cursive (P<0.0026; OR: 2.22; CI95: 1.73-2.86) and (v) multiparous (P<0.0001; OR: 2.90; CI95: 2.17-3.87). The results indicate a widespread of CAEV infection in goat herds in southern Spain, being herd size, existence of kidding area, absence of cleaning and disinfection program, natural mating and multiparous goats risk factors for the exposure to CAEV.
... Approximately 30-80% of dairy goats in the US, Canada and Europe are infected, compared with 0-10% in Africa and South America (Crawford and Adams 1981;Adams et al. 1984;East et al. 1987;Phelps and Smith 1993;Rowe and East 1997). In dairy herds, mammary tropism has economic consequences on milk production, mammary pathology (Smith and Cutlip 1988;Greenwood 1995;Martínez-Navalón et al. 2013), early culling and loss of export potential (Peretz and Cimarosti 1990). ...
The risk of transmission of caprine arthritis encephalitis virus (CAEV) during embryo transfer has been demonstrated in vivo through the detection of CAEV proviral DNA in: (1) flushing media for embryo collection; (2) cells of the cumulus oophorus surrounding the oocytes, ovarian follicle, oviduct and uterine tissues; and (3) testis, epididymis, vas deferens and vesicular glands. Experimentally infected embryos without a zona pellucida (ZP), washed 10 times with Minimum Essential Media (MEM) and 5% Fetal Calf Serum (FCS) solution, were capable of transmitting CAEV. In vitro we demonstrated that granulosa, oviductal, epididymal and embryo cells are fully susceptible to CAEV infection and allow active replication. However, AI with in vitro-infected semen can result in the production, after ten washing, of CAEV-free embryos, and ten washing in vitro- or in vivo-infected embryos with an intact ZP, or ten washing oocytes with an intact ZP, resulted in the production of virus-free female gametes or embryos that can be used for IVF or embryo transfer. Therefore, we have demonstrated that: (1) that CAEV-free embryos can be produced by IVF using spermatozoa infected in vitro by CAEV; and (2) embryo transfer can be used under field conditions to produce CAEV-free kids from CAEV-infected biological mothers.
Introduction
Maedi-visna virus and caprine arthritis encephalitis virus are two closely related lentiviruses which cause multisystemic, progressive and persistent infection in goats and sheep. Because these viruses frequently cross the species barrier, they are considered to be one genetic group called small-ruminant lentiviruses (SRLV). They have in vivo tropism mainly for monocytes and macrophages and organ tropism with unknown mechanisms. Typical clinical signs are pneumonia in sheep, arthritis in goats, and mastitis in both species. Infection with SRLV cannot currently be treated or prevented, and control programmes are the only approaches to avoiding its spread. These programmes rely mainly on annual serological testing and elimination of positive animals. However, the high genetic and antigenic variability of SRLV complicate their early and definitive diagnosis. The objective of this review is to summarise the current knowledge of SRLV genetic variation and its implications for tropism, the development of diagnostic tests and vaccines and the effectiveness of control and eradication programmes.
Material and Methods
Subject literature was selected from the PubMed and the Google Scholar databases.
Results
The high genetic diversity of SRLV affects the performance of diagnostic tools and therefore control programmes. For the early and definitive diagnosis of SRLV infection, a combination of serological and molecular tests is suggested. Testing by PCR can also be considered for sub-yearling animals. There are still significant gaps in our knowledge of the epidemiology, immunology and biology of SRLV and their impact on animal production and welfare.
Conclusion
This information may aid selection of the most effective SRLV spread reduction measures.
A two-year longitudinal cohort study was conducted on a total of 407 purebred Chios and Lacaune ewes from four intensive dairy sheep farms to assess potential risk factors for small ruminant len-tiviruses (SRLVs) seropositivity. Ewes were serologically tested semiannually at pre-mating and pre-lambing, and their age, breed, and body condition score (BCS) were recorded. Εwes were cat-egorized as constantly seronegative, constantly seropositive, seroconverted, seroreverted, or ani-mals with an intermittent presence of antibodies. Mixed binary logistic regression models were used to estimate the adjusted relative risks of the studied risk factors for (i) the individual ewes’ sero-positivity, (ii) the manifestation of specific serological patterns, and (iii) the occurrence of sero-conversion and seroreversion incidents. Increased age was associated with seropositivity and con-stantly seropositive status (p < 0.001 in both cases). On the other hand, age was negatively associated with constantly seronegative pattern, seroconversion incident, and the intermittent presence of an-tibodies (p < 0.05 in all cases). Moreover, breed was recognized as a risk factor: Lacaune ewes demonstrated increased seropositivity, whereas Chios ewes were more likely to demonstrate an intermittent presence of antibodies (p < 0.01 in both cases). Seropositive status (p < 0.001), sero-positivity in animals with an intermittent presence of antibodies (p = 0.001), and seroconversion incidents (p < 0.001) were significantly increased at pre-lambing compared to pre-mating. The risk factors recognized in our study contribute to a better understanding of SRLVs epidemiology and the evidence-based designation of SRLVs’ control programs in intensive dairy sheep farms in Greece.
Small ruminant lentivirus (SRLV) are infected and transmitted among ovine and caprine species. This disease is a severe problem for small ruminant production, not only for animals’ wellbeing but also for the herd’s efficiency. The main aim of this research was to quantify the seroprevalence and associated risk factors for SRLV infection in the north region of Portugal. Collected samples from a total of 150 herds, of which 129 (86.0%; 95% CI: 80.67% - 91.33%) had at least one seropositive animal. Out of 2607 individual blood samples, 1074 (41.2%) were positive for SRLV. The risk factors associated with SRLV infection were: specie (caprine), age (> 2 years old), herd size (> 100 animals), production system (intensive), production aptitude (milk), type of activity (professional), participation in livestock competitions (yes), buy replacement young ewe (yes) and rearing (natural). This knowledge empowers the implementation of effective preventive measures. Overall, biosecurity measures should be promoted and implemented to aim reducing viral transmission, with the main goal of reducing the prevalence of this disease. Completely, we understand that government authorities should promote and audit voluntary control and eradication programs in small ruminant herds in the region studied.
This study aimed to provide information on the presence and frequency of viral and parasitic agents in wildlife presented to a Veterinary Teaching Hospital in 2020–2021. Serum and faecal samples were collected from 50 rescued animals (roe deer, fallow deer, foxes, badgers, pine martens, and porcupines) and examined by serological, molecular, and parasitological techniques. Transtracheal wash (TTW) was also collected post-mortem from roe deer. Overall, the results of the different techniques showed infections with the following viral and parasitic agents: Bovine Viral Diarrhea Virus, Small Ruminant Lentiviruses, Kobuvirus, Astrovirus, Canine Adenovirus 1, Bopivirus, gastrointestinal strongyles, Capillaria, Ancylostomatidae, Toxocara canis, Trichuris vulpis, Hymenolepis, Strongyloides, Eimeria, Isospora, Dictyocaulus, Angiostrongylus vasorum, Crenosoma, Dirofilaria immitis, Neospora caninum, Giardia duodenalis, and Cryptosporidium. Sequencing (Tpi locus) identified G. duodenalis sub-assemblages AI and BIV in one roe deer and one porcupine, respectively. Adult lungworms collected from the TTW were identified as Dictyocaulus capreolus (COX1 gene). This is the first molecular identification of G. duodenalis sub-assemblage AI and D. capreolus in roe deer in Italy. These results show a wide presence of pathogens in wild populations and provide an overview of environmental health surveillance.
This datasheet on caprine arthritis encephalitis covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Hosts/Species Affected, Diagnosis, Pathology, Epidemiology, Impacts, Prevention/Control, Further Information.
The goat's udder is composed of two glands, called halves or sides. Neoplasms of the parenchyma of the udder are rarely reported in goats. Udder development and even milk production are relatively common in unbred doelings of dairy breeds. Skin diseases that are frequently localized to the udder include bacterial folliculitis and contagious ecthyma. Lesions of the udder caused by staphylococcal infection include folliculitis, moist dermatitis in the intramammary sulcus, and deep furuncles. Mastitis, or inflammation of the mammary gland, is a broad diagnosis that may be based on changes in the physical characteristics of the udder or its secretion. The presence of blood or unpleasant flavors in goat milk decreases the desirability of milk and cheese for human consumption. Several types of commercial home pasteurizers are available to simplify making goat milk safe for human consumption.
Small ruminant lentiviruses (SLRVs) have been recognized throughout the world for decades. SLRVs are a heterogenous group of viruses that can infect sheep, goats, and wild ruminants. Evidence supports cross-species infection. These viruses cause lifelong infections where they target specific organs, which can result in production losses due to diminished milk production, consequential increases in neonatal death and diminished growth, and premature culling of prime age animals. No vaccine or treatments have proved effective. Control programs rely on an understanding of viral transmission and application of highly sensitive, specific, and frequent testing regimens.
Staphylococcus aureus is the most important cause of clinical mastitis in goats, and non-aureus staphylococci is the most common isolate from subclinical mastitis. Environmental streptococci are a severe problem. Somatic cell counts and California mastitis test are a screening test for mastitis and an indicator of poor udder health, but values should be interpreted differently than with dairy cattle. Somatic cell scores likely are a more useful way of viewing data. High bacterial counts in milk are common; mastitis may be involved as a cause. Proper udder preparation, milking procedure, and postmilking management are key factors in mastitis control.
Visna/Maedi is a disease of sheep caused by small ruminant lentivirus (SRLV) infection that is widespread throughout the world and that has been recognized to be present in the Basque Country (Spain) since the early 1980's. Nearly seven decades of studies have improved the knowledge on its clinical signs and epidemiology. However, its slow progressive nature, subclinical most of the time, makes difficult to assess its real impact on productive traits, a question of critical importance to balance out the economic costs it causes and the benefits of designing and deploying an eradication program. Development of a dairy breeding program since the 90 s in the local Latxa sheep population has provided data on milk productivity in several flocks where SRLV infection prevalence has been continuously monitored. This study analyses retrospectively the association between SRLV prevalence and production variables during ten yearly lactations in three Latxa dairy flocks with medium-high SRLV seroprevalence. Our results indicate that average standard lactation of seropositive sheep was 6.7 % lower than controls. The largest differences (p < 0.001) were observed at the ewe lifetime peak of production between second and fourth lactations. Lifelong milk and lamb production data indicated even a higher impact, with costs rising up to nearly 50 €/ewe/year. This substantial production decrease associated with subclinical SRLV infection in Latxa dairy sheep supports the benefit of establishing a SRLV control program. A rough cost-benefit analysis indicated that even in a medium-yielding breed, testing expenses would be largely covered by milk production improvement.
Background
Paratuberculosis (PTB) is a chronic, enteric wasting disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP), with a worldwide distribution. Andalusia, located in southern Spain, is one of the European regions with the highest goat census and the highest milk production; however, current data on the prevalence of MAP in this species are not available.
Methods
A cross-sectional study was performed to determine the seroprevalence and risk factors associated with PTB in dairy goat flocks from southern Spain. A total of 3312 serum samples were collected from 48 flocks located in three different geographical areas. Health and productive parameters were surveyed during the visit to the herds.
Results
A total of 511 goats were seropositive, with overall true seroprevalence of 22.54 per cent (95 per cent confidence interval (CI 95 ) 21.12–23.97). Of the goat herds, 87.50 per cent (CI 95 78.14–96.98) were seropositive. The intraherd seroprevalence was 25.43±31.71, distributed as follows: 22 flocks with a seroprevalence under 10 per cent; 18 flocks between 10 per cent and 50 per cent; and eight flocks with a frequency over 50 per cent. Multivariate logistic regression showed significant association between PTB seropositivity and the following variables: intensive production system , lack of management by batches , inappropriate ventilationandseropositivity tocaprinearthritisencephalitisvirus (CAEV) .
Conclusions
The results indicate a widespread PTB infection in goat herds in southern Spain. Thus, control programmes must include management and sanitary measures to reduce the prevalence. Further experimental studies are necessary to determine the influence of CAEV-PTB coinfection on immune status.
Caprine Arthritis Encephalitis is an endemic disease in goat breedings, caused by viral strains belonging to the Small Ruminant Lentivirus group and characterized by a progressive chronic course. Its clinical signs are not immediately recognizable and can only be detected via costly serological tests. No vaccine is available. Two main strategies for fighting it are in common use. The “test-and-slaughter” approach, that selects infected goats and directly slaughters them, is expensive, time consuming and often leads to endemic low level persistence of the infection. Alternatively, newborns are removed from their mothers to be raised by healthy goats. After weaning they would rejoin their breeds, but then they could still be subject to horizontal contagion. In this study a mathematical model that considers the cocirculation of two different SRLV viral genotypes (B and E) is devised and analyzed, based on the key assumption of perfect cross-protection between the two genotypes’ infections. Two strategic measures arise from its analysis, that are strongly recommended and whose implementation is encouraged: in the presence of both genotypes, the farmer should not isolate the newborns from their mothers but rather raise them with all the other animals. In the case of genotype-B-only affected farm, serological testing and mother-offspring separation should still be considered the best strategy for CAEV control. These strategies completely reverse the current removal policy and, in due conditions, would lead to disease eradication. These represent very reasonable and cheap measures for the eventual control of the epidemics.
Goats’ milk is an attractive product for producers and consumers, because of its health benefits and chemical composition. But there arestill no strict regulations according to specific hygienic rules for this milk safety. Somatic cells number, which is thebasic parameter for bovine milk (SCC) vary in goats and it is affected by many factors, e.g. age, estrous phase, type of milking, but also by infectiousfactors. In our experiment we had analyzed the potential influence of CAEV infection on dairy goats productivity and milk SCC. The experiment was conducted on 24 individuals (12 seropositive/12 seronegative) , with milk samples analysis during subsequent lactations (from 2nd to 5th). The results have shown the impact of viral infection on early and late lactations, with decreased milk yield and increased number of somatic cells in milk. We conclude that it could be correlated with infection progression and the efficiency of goats’ immune system.
We carried out this study to determine for how long small ruminant lentivirus (SRLV)‐specific antibodies can be detected by three commercial ELISA kits in goat kids after suckling infected does in field conditions. Forty‐one kids born to SRLV‐seropositive asymptomatic does were blood sampled prior to colostrum consumption, and then weekly for 6 months in total. The sera were screened with three commercial ELISA kits: whole‐virus ELISA (wELISA), recombinant transmembrane and capsid antigen ELISA (TM/CA‐ELISA), and surface antigen ELISA (SU‐ELISA). All but one kid were seronegative in all three ELISAs right after birth. At the age of 1 week all kids turned seropositive in wELISA, 39 kids (95%) in TM/CA‐ELISA, and 35 kids (85%) in SU‐ELISA. All seropositive kids turned seronegative in wELISA by the 15th week, and in SU‐ELISA by the 19th week (median of 8 weeks in both ELISA), whereas in TM/CA‐ELISA five kids (13% of 39 initially seropositive) were still seropositive at the age of 6 months (median of 11 weeks). Antibody levels at the age of 1 week proved significantly linked to the duration of maternal antibodies in all three ELISAs and could be employed to predict for how long maternal antibodies would remain detectable.
Caprine arthritis-encephalitis (CAE) represents an economic problem for goat farming in several European countries, including Italy. This study examined the effects of the caprine arthritis-encephalitis virus on lactational performance of goats on a farm in Northern Italy. Goat blood sera were examined for the presence of antibodies to CAEV by using enzyme-linked immunosorbent assay (ELISA) and Western blots (WB). The results of ELISA and Western blotting for antibodies against caprine arthritis-encephalitis virus were compared with milk production records. Mean values of milk production, protein, fat, lactose and somatic cell counts (SCC) were compared for primiparous goats that were negative and positive for presence of the virus. The results from 31 lactating goats suggested that milk production was similar for goats that tested seropositive and those that tested seronegative. Seropositive primiparous goats showed a slightly higher mean annual milk production and percentage of fat (P < 0.05), while negative primiparous goats had significant greater percentage of milk protein (P < 0.001) and decreased log10 SCC (P < 0.001). Seropositive primiparous goats had lactational averages of 2.94 kg/day for milk, 3.04%, 2.95% and 5.85 log10 cells/ml for concentrations of fat, protein and SCC, respectively. In contrast, seronegative goats were characterized by an average milk yield of 2.76 kg/day with concentrations of fat, protein and SCC of 2.77%, 3.48% and 5.38 log10 cells/ml, respectively. No significant difference in milk lactose concentration was observed between seronegative (4.54%) and seropositive (4.34%) goats.
Bacteriology, somatic cell counts (SCO) and N-acetyl-β-glucosaminidase (NAGase) activity determinations were conducted on milk samples collected from does in three dairy herds with caprine arthritis–encephalitis virus (CAEV) infection. In two herds, CAEV-infected does were more likely to have a subclinical bacterial infection of the udder than CAEV-free does (P < 0·05). Does with CAEV but no bacterial udder infection had significantly greater mean SCO and NAGase activity than CAEV-free does without udder infection (P < 0·01). In two herds, changes in milk SCC and NAGase associated with CAEV infection were similar to those produced by coagulase-negative staphylococcal infections. The findings confirm that indirect indicators of bacterial mastitis infection may have reduced specificity in dairy goat herds with CAEV.
The presence of caprine arthritis and encephalitis (CAE) in Spain has never been officially acknowledged but it is suspected. Goats have been imported from other European countries with a high prevalence of the disease, mainly France, and they might have introduced the disease into the indigenous goat population. A serological survey of caprine arthritis and encephalitis virus antibodies was carried out in 22 volunteer dairy Murciano-Granadina goat herds; 2513 lactating goats were tested with an agar gel immunodiffusion test, and 12.1 per cent were found to be positive. Five of the herds were free of infection, six had a low prevalence of the disease, five had a medium prevalence and six had a high prevalence. Five seropositive goats with clinical signs of CAE were studied. Macroscopic and microscopic lesions similar to those described for CAE were detected in all five goats and a cytopathic effect typical of CAE virus was observed in primary explant cultures from four of them.
The objective of the study was to evaluate the diagnostic performances of the ELITEST-MVV ELISA for detection of antibodies against small ruminant lentiviruses and of two recently published PCRs for the detection of proviral DNA of SRLV in blood and corresponding individual milk samples. In addition, the feasibility of bulk milk testing was investigated by titrating ELISA positive pooled milk samples in negative milk, and by investigating bulk milk samples by ELISA and PCR in relation to the SRLV-status of the flocks. The results show that plasma and milk are suitable replacements for serum. For sheep, both PCRs showed a better diagnostic performance than for goats. ELISA results for bulk milk samples were promising with a putative detection limit of <3% within-herd prevalence using 1/10 pre-diluted samples and even <1% within-herd prevalence when samples were tested undiluted. In a panel of 249 bulk milk samples, all samples from SRLV free flocks (n=138) tested negative in the ELISA, while 50% of the samples from flocks with an unknown SRLV-status (n=111) were positive. For a subset of 59 bulk milk samples, agreement between ELISA results and leader-gag PCR results was almost 100%. These results demonstrate the potential of bulk milk testing as a cost effective tool for early detection of infection in dairy flocks, which is essential for SRLV-monitoring programs.
In order to provide further evidence for the association of an indurative lymphocytic mastitis in sheep with MVV (maedi-visna virus) infection, an experimental study was performed. Fourteen MVV-free pregnant ewes, 2 years of age, were divided into two groups. Eight were intravenously inoculated with MVV (strain ZZV-1050); six ewes served as sham-inoculated controls. Post-mortem examinations were carried out at 8, 16 and 28 months. After 8 months, the 3 infected ewes had indurated udders with extensive lymphoid proliferation around lactiferous ducts and in the acinar tissue. The ducts were often partially obliterated. After 16 months, one of the two infected ewes suffered from indurative lymphocytic mastitis. The other was free of specific udder lesions. After 28 months only one of three infected ewes had mild lymphocytic infiltration in the udder. None of the controls, two in each post-mortem session, had lesions typical of this form of mastitis. The lesions were most severe 8 months after infection. At 16 and 28 months lesions were of a lesser degree or were absent. The lung lesions in the infected ewes 8 months after inoculation were similar to the changes in the udder regarding the lymphoid accumulation, although the proliferation around bronchial tree and blood vessels was less pronounced. After 16 and 28 months all infected ewes had peribronchial and perivascular lymphocytic infiltration though of a lesser degree than after 8 months. From these results it is concluded that in addition to the lung and brain lesions MVV infections may cause a specific indurative lymphocytic mastitis.
Ovine and caprine lentiviruses share the capacity to induce slowly progressive and inflammatory diseases of the central nervous system (leukoencephalitis or visna), lungs (progressive pneumonia or maedi), and joints (arthritis) in their natural hosts. Studies on their replication indicated that ovine lentiviruses and caprine arthritis-encephalitis virus (CAEV) recently isolated in the United States establish persistent infection in ovine and caprine fibroblasts, whereas older prototype ovine lentiviruses such as Icelandic visna virus or American progressive pneumonia virus irreversibly lyse fibroblast cultures. Since all of the recent isolates were found to be persistent, Narayan et al. (J. Gen. Virol. 59:345-356, 1982) concluded that the highly lytic viruses were only tissue-culture-adapted strains. In the present report, we isolated new ovine lentiviruses from French sheep with naturally occurring progressive pneumonia which are either highly lytic (five isolates), as are the Icelandic strains of visna virus, or persistent (one isolate), as are CAEV or American persistent ovine lentiviruses. Protein and nucleic acid content analyses of these new highly lytic (type I) and persistent (type II) isolates indicated that type I and type II ovine lentiviruses were genetically distinct, type I and type II viruses being closely related to the Icelandic strains of visna virus and to CAEV, respectively. We conclude that (i) highly lytic ovine lentiviruses, such as the Icelandic prototype strains of visna virus and persistent lentiviruses more related to CAEV, are naturally present in the ovine species, and (ii) irreversible cell lysis induced by highly lytic viruses does not result from a tissue culture adaptation of field isolates that were originally persistent but is instead the consequence of a genetic content distinct from that of persistent viruses.
Bacteriology, somatic cell counts (SCC) and N-acetyl-beta-glucosaminidase (NAGase) activity determinations were conducted on milk samples collected from does in three dairy herds with caprine arthritis-encephalitis virus (CAEV) infection. In two herds, CAEV-infected does were more likely to have a subclinical bacterial infection of the udder than CAEV-free does (P < 0.05). Does with CAEV but no bacterial udder infection had significantly greater mean SCC and NAGase activity than CAEV-free does without udder infection (P < 0.01). In two herds, changes in milk SCC and NAGase associated with CAEV infection were similar to those produced by coagulase-negative staphylococcal infections. The findings confirm that indirect indicators of bacterial mastitis infection may have reduced specificity in dairy goat herds with CAEV.
Maedi-visna virus (MVV) is a lentivirus of sheep, mainly affecting the lungs and the central nervous system. Long terminal repeat (LTR) sequence variability is common in tissue culture-derived isolates of MVV as well as those of other lentiviruses. The role of this sequence variation in MVV replication has not been explored. PCR amplification of the LTRs of an MVV isolate revealed two product sizes, the larger containing a 53 bp duplication. PCR products containing the two size variants of the LTRs were cloned into an infectious molecular clone of MVV and the resulting chimeric viruses were tested for growth in various cell types. The chimeric virus containing only one copy of the 53 bp sequence was found to grow more slowly in sheep choroid plexus cells, sheep fibroblasts and sheep synovial cells than the virus with the 53 bp duplication. Both viruses grew equally well in macrophages. These results indicate that the LTRs determined the extended cell tropism of MVV.
Staphylococci are the main aetiological agents of small ruminants intramammary infections (IMI), the more frequent isolates being S. aureus in clinical cases and coagulase negative species in subclinical IMI. The clinical IMI, whose annual incidence is usually lower than 5%, mainly occur at the beginning of machine milking and during the first third of lactation. These features constitute small ruminant peculiarities compared to dairy cattle. Small ruminant mastitis is generally a chronic and contagious infection: the primary sources are mammary and cutaneous carriages, and spreading mainly occurs during milking. Somatic cell counts (SCC) represent a valuable tool for prevalence assessment and screening, but predictive values are better in ewes than in goats. Prevention is most often based on milking machine management, sanitation and annual control, and milking technique optimisation. Elimination mainly relies on culling animals exhibiting clinical, chronic and recurrent IMI, and on drying-off intramammary antibiotherapy; this treatment allows a good efficacy and may be used selectively by targeting infected udders only. Heritability values for lactation mean SCC scores are between 0.11 and 0.15. Effective inclusion of ewe's mastitis resistance in the breeding goal has recently been implemented in France following experimental and large scale estimations of genetic parameters for SCC scores.
Small ruminant lentiviruses (SRLV = maedi-visna in sheep and caprine arthritis encephalitis in goats) are distributed throughout most countries of the world, particularly Europe. Laboratories from 16 European countries established collaborations within the framework of a COST (CO-operation in the field of Scientific and Technical Research) action sponsored by the European Union in order to (i) better organize their research programmes on SRLVs and (ii) to coordinate efforts to combat these two diseases. After five years, a consensus conference--the first one in the veterinary medicine field--concluded the work of this network of laboratories by reviewing the present position and discussing three important questions in the field of SRLVs: routes of transmission, consequences of infection and potential role of eradication programmes at either a European or local level, according to the situation in each country or region. This paper brings together existing information regarding these questions and identifies areas for future research.
The study was aimed at identifying the pathogens causing subclinical udder infections in representative Israeli dairy goat herds and determining their effect on milk quality. Five hundred goats in ten flocks of various breeds and crossbreeds were surveyed. Of the 500 goats, 13.4% were in their first lactation, 36.4% were in their second lactation and 50.2% were in their third or higher lactation. Percentages of udder halves with subclinical intramammary infection in the flocks ranged from 35 to 71%. The effect of the bacteriological infection on somatic cells count (SCC) was significant (P<0.001). Various species of coagulase-negative staphylococci (CNS), mainly Staphylococcus caprae and Staphylococcus epidermidis, were the main pathogens in infected udder halves. Lactation number did not significantly influence either infection rate of udder halves or SCC, although the percentage of udder halves with no bacteriological findings was higher at the first lactation than at the third lactation. Milk composition (fat, protein and lactose) varied among flocks, with lower mean total protein in uninfected halves than in infected ones and higher lactose in uninfected than infected halves.
In the mid-1980s, Switzerland started a programme to eradicate caprine arthritis-encephalitis - an infectious disease of goats caused by the small ruminant lentivirus (srlv). Since 1996, progress towards eradication has slowed down, owing to infections occurring on farms from which the infection had previously been eliminated. To investigate specific risk factors for these new infections and to improve the eradication programme, a case-control study was conducted. Cases consisted of farms that had been officially free of srlv for at least three consecutive years but on which at least one srlv-seropositive animal had been detected during the annual serological surveys of 2001 and 2002. On all the case and control farms where sheep were housed together with goats, a subset of sheep was screened for antibodies to srlv. Potential risk factors were analysed in a logistic regression model; the results indicated that close contact with srlv-seropositive sheep was highly correlated with seroconversion in srlv-seronegative goat herds (odds ratio=26.9), supporting the hypothesis that srlv can be transmitted between sheep and goats, and suggesting that the measures taken so far will not lead to the complete eradication of srlv from Switzerland within the next few years.
Maedi-Visna Virus (MVV) seroprevalence and its relationship with housing and mode of rearing of replacement ewe-lambs was investigated in 38 non-randomly selected sheep-flocks in Spain. They included extensive lamb-producing Manchega cross-bred flocks raised almost permanently at pasture, semi-intensive Latxa dairy flocks housed 2-8 months/year and intensively raised Assaf dairy flocks housed most time and at higher stocking density in less ventilated buildings than other flocks. Most flocks raised replacement lambs naturally with their dams until weaning and as a separate flock thereafter until lambing at one year of age. Seroprevalence (95% confidence intervals) was 77%, 25% and 5% (4-6) in intensive, semi-intensive and extensive flocks, respectively and the median (interquartile range) flock-seroprevalence was 82% (66-94) in intensive flocks, 31% (14-31) in semi-intensive flocks and 4% (0-7) in extensive flocks. Seroprevalence was lowest in one year-old sheep and increased to flock levels during the year after introduction into the adult flock in most intensive flocks and more gradually in other flocks. Adult flock seroprevalence was associated with housing time but this relationship was not evident within a particular rearing system, indicating that other unknown factors are critical in horizontal MVV-transmission. Low seroprevalence in extensive flocks further supports previous indications that lactogenic MVV-infection is relatively inefficient and horizontal transmission is necessary to ensure long-term maintenance of MVV and this could explain that MVV has not been reported from countries with mainly extensively reared sheep such as Australia and New Zealand. Moreover, it indicates that MVV-control in extensive and semi-intensive flocks can be simple and inexpensive.
Recombination of different strains and subtypes is a hallmark of lentivirus infections, particularly for human immunodeficiency virus, and contributes significantly to viral diversity and evolution both within individual hosts and within populations. Recombinant viruses are generated in individuals coinfected or superinfected with more than one lentiviral strain or subtype. This, however, has never been described in vivo for the prototype lentivirus maedi-visna virus of sheep and its closely related caprine counterpart, the caprine arthritis-encephalitis virus. Cross-species infections occur in animals living under natural conditions, which suggests that dual infections with small-ruminant lentiviruses (SRLVs) are possible. In this paper we describe the first documented case of coinfection and viral recombination in two naturally infected goats. DNA fragments encompassing a variable region of the envelope glycoprotein were obtained from these two animals by end-limiting dilution PCR of peripheral blood mononuclear cells or infected cocultures. Genetic analyses, including nucleotide sequencing and heteroduplex mobility assays, showed that these goats harbored two distinct populations of SRLVs. Phylogenetic analysis permitted us to assign these sequences to the maedi-visna virus group (SRLV group A) or the caprine arthritis-encephalitis virus group (SRLV group B). SimPlot analysis showed clear evidence of A/B recombination within the env gene segment of a virus detected in one of the two goats. This case provides conclusive evidence that coinfection by different strains of SRLVs of groups A and B can indeed occur and that these viruses actually recombine in vivo.
SAS PROC MIXED is a flexible program suitable for fitting multilevel models, hierarchical linear models, and individual growth models. Its position as an integrated program within the SAS statistical package makes it an ideal choice for empirical researchers and applied statisticians seeking to do data reduction, management, and analysis within a single statistical package. Because the program was developed from the perspective of a "mixed" statistical model with both random and fixed effects, its syntax and programming logic may appear unfamiliar to users in education and the social and behavioral sciences who tend to express these models as multilevel or hierarchical models. The purpose of this paper is to help users familiar with fitting multilevel models using other statistical packages (e.g., HLM, MLwiN, MIXREG) add SAS PROC MIXED to their array of analytic options. The paper is written as a step-by-step tutorial that shows how to fit the two most common multilevel models: (a) school effects models, designed for data on individuals nested within naturally occurring hierarchies (e.g., students within classes); and (b) individual growth models, designed for exploring longitudinal data (on individuals) over time. The conclusion discusses how these ideas can be extended straighforwardly to the case of three level models. An appendix presents general strategies for working with multilevel data in SAS and for creating data sets at several levels.
Small Ruminant Lentivirus is transmitted vertically by ingestion of contaminated milk/colostrum and horizontally by the respiratory route through close contact with infected animals. In order to detect presence of virus in a shed environment, we sampled and tested drinking water, pen air and air exhaled from infected sheep in both commercial flocks and groups of culled sheep. Nucleic acids were extracted and analysed by retrotranscription, Pol PCR amplification and sequencing. Virus sequences were detected in 9% and 11% of samples of water and air, respectively, collected from pens, and in 35% of sheep whose expelled air was tested. Our results are in concordance with previous evidences of air and waterborne transmission of the infection and might have implications for the design of control strategies.
SAS PROC MIXED is a flexible program suitable for fitting multilevel models, hierarchical linear models, and individual growth models. Its position as an integrated program within the SAS statistical package makes it an ideal choice for empirical researchers and applied statisticians seeking to do data reduction, management, and analysis within a single statistical package. Because the program was developed from the perspective of a "mixed" statistical model with both random and fixed effects, its syntax and programming logic may appear unfamiliar to users in education and the social and behavioral sciences who tend to express these models as multilevel or hierarchical models. The purpose of this paper is to help users familiar with fitting multilevel models using other statistical packages (e.g., HLM, MLwiN, MIXREG) add SAS PROC MIXED to their array of analytic options. The paper is written as a step-by-step tutorial that shows how to fit the two most common multilevel models: (a) school effects models, designed for data on individuals nested within naturally occurring hierarchies (e.g., students within classes); and (b) individual growth models, designed for exploring longitudinal data (on individuals) over time. The conclusion discusses how these ideas can be extended straighforwardly to the case of three level models. An appendix presents general strategies for working with multilevel data in SAS and for creating data sets at several levels.
The effects of caprine arthritis-encephalitis virus (CAEV) on performance of a dairy goat herd during a 2 year period were examined. The herd comprised approximately 200 head including 57-80 lactating does. A significant increase (PcO.05) due to CAEV was apparent for reproductive failure among multiparous does (43% vs. 18%). Kid birth weights (mean f SE 3.4 f 0.1 vs. 3.6 ? 0.1 kg) and growth rates prior to (148 f 14 vs. 194 Ifr 5 g day-') and during the weaning period (34 ? 20 vs. 111 -t 28 g day-') were also adversely affected in kids of CAEV infected does (P-c 0.05). Seropositive multiparous does had lower
Nucleotide sequences of small ruminant lentiviruses (SRLVs) were determined in sheep and goats, including progeny of imported animals, on a farm in Mexico. On the basis of gag-pol, pol, env and LTR sequences, SRLVs were assigned to the B1 subgroup, which comprises caprine arthritis-encephalitis virus (CAEV)-like prototype sequences mainly from goats. In comparison with CAEV-like env sequences of American and French origin, two putative recombination events were identified within the V3-V4 and V4-V5 regions of the env gene of a full length SRLV sequence (FESC-752) derived from a goat on the farm.
Small ruminant lentiviruses (SRLVs) cause different clinical forms of disease in sheep and goats. So far in Spain, Maedi visna virus-like (MVV-like) sequences have been found in both species, and the arthritic SRLV disease has never been found in sheep until a recent outbreak. Knowing that arthritis is common in goats, it was of interest to determine if the genetic type of the virus involved in the sheep arthritis outbreak was caprine arthritis encephalitis virus-like (CAEV-like) rather than MVV-like. Alignment and phylogenetic analyses on nucleotide and deduced amino acid sequences from SRLV of this outbreak, allowed a B2 genetic subgroup assignment of these SRLV, compatible with a correspondence between the virus genetic type and the disease form. Furthermore, an isolate was obtained from the arthritic outbreak, its full genome was CAEV-like but the pol integrase region was MVV-like. Although its LTR lacked a U3 repeat sequence and had a deletion in the R region, which has been proposed to reduce viral replication rate, its phenotype in sheep skin fibroblast cultures was rapid/high, thus it appeared to have adapted to sheep cells. This outbreak study represents the first report on CAEV-like genetic findings and complete genome analysis among Spanish small ruminants.
Three consecutive years of monitoring 248 goats in the same flock, found that the first lactation milk yield was significantly higher in seronegative (578L) than in seropositive (447L) animals but this difference disappeared in the subsequent second to fourth lactations. No significant differences were found in the proportions of seronegative and seropositive does in the flock, the percentage of animals culled, the number of offspring, or in the number of cases of udder bacterial infection, irrespective of age. Removal of kids from their dams before suckling and the feeding of pasteurised colostrum resulted in reduced numbers of seropositive animals. Nevertheless, by approximately 24 months of age, 76.9% of these initially seronegative animals were seropositive, a factor that significantly contributed to flock seropositivity. This finding could be attributed to lateral virus transmission from seropositive to seronegative kids because of lack of segregation within the flock.
Small ruminant lentiviruses (SRLVs), including maedi-visna virus (MVV) of sheep and caprine arthritis-encephalitis virus (CAEV), are widespread, cause fatal diseases and are responsible for major production losses in sheep and goats. Seventy years after the legendary maedi-visna sheep epidemic in Iceland, which led to the first isolation of a SRLV and subsequent eradication of the infection, no vaccine or treatment against infection has been fully successful. Research during the last two decades has produced sensitive diagnostic tools, leading to a variety of approaches to control infection. The underlying difficulty is to select the strategies applicable to different epidemiological conditions. This review updates the knowledge on diagnosis, risk of infection, immunisation approaches and criteria for selecting the different strategies to control the spread of SRLVs.
Maedi-visna, a multisystemic disease of adult sheep, was first described in Spain in 1984. To get an idea of the seroprevalence of the disease locally and to estimate the number of seropositive animals with lesions, samples of blood, lungs and mammary glands were taken from 124 randomly selected sheep killed in the main slaughterhouse of Zaragoza. In the agar gel immunodiffusion test, 74 (59.7 per cent) of the sheep were positive and 50 were negative. Among the 74 seropositive animals, 19 (25.6 per cent) had no lesions in any organ, 12 (16.2 per cent) had lesions in the lungs only, 15 (20.2 per cent) had lesions in the mammary glands and 28 (37.8 per cent) had lesions in both organs. In the lungs hyperplasia of lymphoid follicles was more evident than an interstitial infiltrate but in the mammary glands this relationship was not observed. Even when the lesions occurred in both organs, they did not show the expected proportion in terms of either type or severity. Among the 50 seronegative sheep, eight (16 per cent) showed maedi-like lesions, formed exclusively by the hyperplasia of lymphoid follicles.
A herd of 15 dairy goats with a previous history of neurological disease in kids was screened for caprine arthritis-encephalitis (CAE) virus infection. Virus was isolated from the PBL of all animals as well as milk from lactating does. All animals had antibody detected by ELISA and gel immuno-diffusion. Two animals from this herd were examined for responses to infection. One was an adult female with poor milk production and the other was a 3-month-old female kid which developed acute neurological disease. Both animals had a chronic mastitis compatible with a viral aetiology, and CAE virus was isolated from the mammary tissue of both. The mammary gland must thus be considered an important target organ for virus infection and dissemination.
A recently assembled commercial herd of Alpine goats was studied. Milk production criteria--305-day milk production (M), butter fat content (BF), and solids nonfat content (SNF)--and somatic cell counts (linear score) were monitored by Dairy Herd Improvement Association test records. Milk samples from all milking goats in the herd were obtained for bacteriologic culture for mastitis organisms on 2 occasions; the infection rate ascribed to major pathogens was 3%. In November 1985, serum specimens were obtained from 154 does in first lactation. Of these, 56 (36%) were seropositive for caprine arthritis-encephalitis (CAE) antibodies by agar gel immunodiffusion (AGID), 91 (59%) were seronegative, and serotest results for 7 (5%) were inconclusive. In December, 80 seronegative and 48 seropositive goats remained in the herd and had 305-day projections available. The median production values for seronegative goats (1,539.5 lb of M, 52 lb of BF, 46 lb of SNF) were higher than those for seropositive goats (1,446 lb of M, 45 lb of BF, 44.5 lb of SNF), but this difference was only significant (t test, P less than 0.05) for BF. Does were ranked by a formula that combined M, BF, and SNF, with a desired minimal daily herd average of 5 lb of M, 3% BF, and 3% SNF. A decision was made not to keep offspring from does of the lowest quartile before CAE test results were obtained. This group consisted of 13 of the 80 (16%) seronegative goats and 18 of the 48 (38%) seropositive goats. Thus, a positive CAE test result by AGID was associated (chi 2, P less than 0.01) with poor production.(ABSTRACT TRUNCATED AT 250 WORDS)
Eighteen ewes were experimentally infected with ovine progressive pneumonia virus and their mammary glands were examined for lesions and virus at 2.5 to 10 years postinoculation. Lesions were seen in 14 of 18 sheep; virus was isolated from 4 of 8 sheep. Lesion consisted of an interstitial accumulation of lymphocytes with periductal lymphoid nodules, and epithelial vacuolation and necrosis at the site of the lymphoid nodules.
Sheep in a flock in which 88 per cent of the ewes had antibodies to maedi-visna virus were clinically examined for udder induration during lactation and after drying off. On both occasions about half of the ewes had indurated udders. Histological examination revealed lymphocytic mastitis associated with maedi-visna virus infection, in the udders of six of 25 hoggs (24 per cent), 21 of 39 shearlings (53.8 per cent) and 42 of 67 ewes (62.7 per cent). Distinct lung lesions were found in 8 per cent of the hoggs, 12.5 per cent of the shearlings and 10 per cent of the ewes. The results of a clinical examination of dry udders were correlated with the histological findings.
This review describes the pathogenesis of a slowly progressive disease complex caused by naturally occurring nononcogenic
retroviruses in sheep and goats. In nature, infections are usually clinically silent, but disease may manifest itself after
prolonged incubation periods. Clinically, this is seen as dyspnea, progressive paralysis, and/or progressive arthritis. In
all organs the basic lesion is inflammatory with infiltration and proliferation of lymphocytes, plasma cells, and macrophages.
Other organ-specific pathologic changes such as primary demyelination in the central nervous system and degeneration of cartilaginous
structures in joints accompany inflammation. The viruses infect tissue-specific macrophage populations in vivo. Viral replication
in these cells is restricted to minimal levels but continues indefinitely in the animal as a result of either failure to induce
specific neutralizing antibodies or antigenic drift when neutralizing antibodies develop. Consistent low-grade viral replication
sets the pace for disease by providing continuous antigenic stimulation for the inflammatory cellular immune response or antibodies
that localize in the target tissues. These cells and immune complexes may have adverse effects on indigenous cell populations.
Features of caprine arthritis-encephalitis, a retrovirus disease of domestic goats, were studied in 60 goats over a 10-year period. The rate of progression and the severity of the disease process were highly variable within and among animals, but the most salient features were chronically swollen joints and bursae, lameness, weight loss, poor coat, mineralization of soft tissue, and death. Of 1,160 goat serum samples from 24 states tested by the immunodiffusion technique, 81% were positive for antibody to caprine arthritis-encephalitis virus antigens.
The lentiviruses, caprine arthritis-encephalitis virus (CAEV) and progressive pneumonia virus (PPV) of sheep, cause major diseases in their respective hosts; however, the infectivity of these viruses for closely related species has not been determined. Experiments were conducted to determine whether CAEV would infect sheep and whether PPV would infect goats. Upon inoculation with CAEV, lambs developed a nonsuppurative arthritis and antibody to CAEV, and the virus was isolated up to 4 months later. Exposure of 3 lambs to CAEV-infected adult goats did not lead to demonstrable infection after 18 months. Young goats inoculated with PPV replicated the virus and developed arthritis and antiviral antibody. These results demonstrate that these distinctly different lentiviruses may infect and cause diseases in species other than their accustomed host. Presently used techniques may not be effective in differentiating which lentivirus is responsible for infection of sheep and goats. Our results also indicate that mixing sheep and goats may adversely influence attempts to eradicate lentiviruses from these species.
The possibility of transmission of caprine arthritis-encephalitis virus between lactating goats by the transfer of infected cells during milking has been examined experimentally. Four virus-free Saanen goats were infected, two in full lactation and two during the drying off period, by instillation of infected allogeneic cells into the milk canal of one-half of the udder. All four goats became infected, as shown by the isolation of virus from peripheral blood monocytes, seroconversion, and presence of typical lesions in the mammary gland. The virus was rapidly and constantly demonstrable in cells from the mammary secretions of the dry goats, but less regularly detected from milk cells from the lactating goats. Virus was more frequently isolated when milk SCC were elevated. Virus was present as often in secretions from the uninoculated half of the udder as the inoculated half. Dry goats seroconverted progressively, although antibody concentrations remained low; the lactating goats developed weak, positive Western blots in the late phase of lactation but only gave positive ELISA titers after drying off and artificial reinduction of lactation. At necropsy, lesions typical of the virus were observed in the mammary tissues of all four goats, and three had arthritis of the carpi.
The effect of the indurative lymphocytic mastitis caused by infection with maedi-visna virus was quantified by comparing the pre-weaning growth of lambs from infected and uninfected ewes under the same conditions. A total of 73 infected, but clinically healthy, ewes and 75 ewes from a maedi-visna virus-free source were purchased to form a new flock; they were all three years old. The ewes were mated and the flock was managed as a normal field flock. Serum samples were taken at regular intervals and tested for antibodies to maedi-visna virus. The lambs were weighed at birth and at 14, 30, 50 and, finally, 80 days old, when they were weaned. The ewes were slaughtered, their udders were examined histologically, and the lesions were assessed by counting the typical lymphocytic follicles. Sixty-six per cent of the ewes that were seropositive at slaughter appeared to have follicles. A statistically significant association was found between the number of follicles in the udder and the reduction in the growth rate of the lambs. Lambs from ewes with the mean number of follicles weighed 1.7 kg less at weaning.
SUMMARY A study of the prevalence, spread and control of caprine arthritis-encephalitis virus (CAEV) in dairy goat herds in New South Wales (NSW) during 1986–1988 found that 56.8% of 1484 goats in 14 dairy herds were infected with CAEV. The prevalence of CAEV infection within most herds not implementing control measures increased during the study. At the end of the study, 59.7% of 1322 goats were infected. The prevalence of CAEV increased with age. Differences between breeds were less apparent. Within seven herds with a high standard of identification of goats, 149 of 812 goats seroconverted in an ELISA. Of these newly infected goats, 142 (95.3%) were > 1 yr of age and 96 (64.4%) were > 2 yr suggesting lateral spread of the virus. Most of the goats > 2 yr of age had been in the milking herd for a minimum of 3 to 6 months.
The high seroconversion rate within the milking herd suggested that factors other than the ingestion of infected colostrum and milk before weaning were important for the spread of CAEV. Observations indicated that behaviour of goats, particularly reproductive behaviour among lactating does, and milking herd management practices are important in the spread of CAEV. A high density of livestock, poor livestock control and contamination of feed, water, equipment and personnel were implicated in transmission. Poorly functioning milking machines may also be involved. CAEV was eradicated from 3 herds by the implementation of strict control measures.
The full extent of genetic diversity among small ruminant lentiviruses (SRLVs), i.e., caprine arthritis encephalitis viruses (CAEVs) and maedi-visna viruses (MVVs), remains unknown. This is due in part to the fact that few sequences of CAEV are available. To contribute to this knowledge, gag, pol, and env nucleotide sequences from an SRLV named CA680 originating from a goat from western France were determined. This analysis revealed that this virus is closely related to the Cork and 63 CAEV American isolates. Mismatched amino acids between the CA680 virus and prototype CAEVs ranged from 6.7, 0. 7, and 17.5% for gag, pol, and SU sequences, respectively. The differences between the CA680 virus and MVV prototypes ranged from 16.5, 12.5, and 32.3% for the protein sequences, respectively. A screening using a heteroduplex mobility assay (HMA) adapted to SRLVs revealed that 6 of 10 caprine virus field isolates were closely related to CA680, indicating that this latter isolate was a prototype of CAEVs common in the west of France. Phylogenetic trees drawn using CA, RT, or SU sequences of numerous SRLVs and rooted with EIAV sequences revealed that CA680 and CAEV prototypes, all infectious for goat, clustered in one group. From these HMA and phylogenetic analyses, it appears that U.S. and French caprine SRLVs form a clade that had emerged from a much more diverse group containing all SRLVs infectious for sheep. These ovine SRLVs form a more ancient group in which the EIAV is rooted.
The effects of caprine arthritis-encephalitis virus on lactational performance of goats were examined. The results of an ELISA for antibodies against caprine arthritis-encephalitis virus were compared with milk production records. Mean production of milk, protein, fat, and lactose and somatic cell counts were compared for seropositive and seronegative goats of similar ages. The results from 1799 lactating goats from 66 herds suggested that milk production was similar for 1-yr-old goats that tested seropositive and those that tested seronegative. For 900 of those goats for which data permitted comparison, milk fat and protein were also similar. A comparison of 331 goats showed that lactose contents did not differ between 1- and 2-yr-old goats, but somatic cell counts were higher in 2-yr-old seropositive goats.
This study used mixed models analysis to demonstrate the advantages of a repeated measures technique for a continuous variable over a single measure technique. As an illustration, the loss of milk yield due to ketosis was studied in 2604 multiparous New York State Holstein cows belonging to eight herds, calving between 1991 and 1993. Two methods of analysis were presented: The first treated milk yield as a continuous, summary measure (projected 305-day milk yield); the second treated milk yield as repeated measurements (test-day milk yields). In the first example, with 305-day milk yield as the outcome, ketosis was treated as a binary covariate. Ketosis had no effect on the 305-day milk yield. In the second example, with monthly test-day milk yields as the outcome, four different covariance structures (simple, compound symmetry, autoregressive, and unstructured) to model the association among the repeated measurements were compared. With this approach, ketotic cows yielded significantly less milk per day both before and immediately after diagnosis than did non-ketotic cows. Based on the goodness-of-fit statistics, it was unclear whether an autoregressive or unstructured covariance structure was best. However, an autoregressive structure, in which the previous and current test-day milk yields are assumed to be correlated, was considered more suitable in this study; it is a simpler and more appropriate covariance structure for this particular problem than is an unstructured covariance structure. Nevertheless, with the test-day approach, any of these correlation structures could be used to estimate milk loss after disease. Based on these findings, it is recommended that a repeated measures approach, rather than a single measure approach, be used to study the short-term effect of disease on milk yield.
Somatic cell counts, the bacteriological condition of the milk and antibodies against caprine arthritis encephalitis virus (CAEV) were measured monthly throughout lactation in 121 lactating goats of the Murcia-Granada breed in four commercial dairy goat herds. The prevalence of bacterial intramammary infection was 5.6 per cent and the prevalence of CAEV infection was 20.6 per cent. An analysis of variance revealed a significant effect of herd, intramammary infection and the interaction between intramammary infection and CAEV on the somatic cell count. In udder halves free of intramammary infection, the somatic cell counts were significantly lower in seronegative goats than in seropositive goats (P<0.05), but the difference was not significant in udder halves persistently infected by bacteria. There was a significant increase in somatic cell counts due to bacterial intramammary infection (P<0.01) in the seronegative goats, but this effect was not present in the seropositive animals.
The ovine maedi-visna (MVV) and caprine arthritis-encephalitis (CAEV) small ruminant lentiviruses (SRLV) exhibit differential species tropism and cytopathic effects in vitro. Icelandic MVV-K1514 is a lytic SRLV which can infect cells from many species in addition to ruminants, whereas a lytic North American MVV strain (85/34) as well as nonlytic MVV strain S93 and CAEV can infect only ruminant cells. In the present study, we determined if differential receptor usage in sheep and goat cells is the basis of differential species tropism or cytopathic phenotype of SRLV. Infection interference assays in sheep and goat synovial membrane cells using pseudotyped CAEV vectors showed that North American MVV strains 85/34 and S93 and CAEV use a common receptor (SRLV receptor A), whereas MVV-K1514 uses a different receptor (SRLV receptor B). In addition, human 293T cells expressing CAEV but not MVV-K1514 envelope glycoproteins fused with a goat cell line persistently infected with MVV-K1514, indicating that MVV-K1514 does not use SRLV receptor A for cell-to-cell fusion. Therefore, our results indicate that the differential species tropism of SRLV is determined by receptor usage. However, receptor usage is unrelated to cytopathic phenotype.
A retrospective analysis of seroconversion to Maedi-Visna virus (MVV) was carried out for 10 infected semi-intensively reared dairy-sheep flocks that were tested annually between 1994 and 1999. Four of the flocks raised replacement lambs artificially with bovine colostrum and milk replacement to avoid lactogenic MVV infection but did not prevent aerosol contact between replacements and other sheep in the flock. Flock culling percentages ranged between 14 and 25% and in eight flocks the number of sheep that seroconverted was similar to or lower than the number of sheep culled--suggesting that incidence could be reduced by culling seropositive sheep without increasing average culling percentages. Random-effects logistic regression indicated that seroconversion was associated positively with increasing contact with infected sheep and with lifetime MV-serological status of the dam (used as a proxy measure of genetic susceptibility), but not with mode of rearing pre-weaning (artificially or with a seropositive or seronegative dam). Our results indicate that when conditions allow efficient horizontal transmission, there is no evidence that lactogenic infection increases the risk of MV infection and that there is an important inheritable component of disease resistance or susceptibility.
Small ruminant lentiviruses (SRLV) are classical slow retroviruses causing chronic inflammatory disease in a variety of target organs. The routes of transmission have been investigated and a large body of evidence has accumulated over many years. The main routes are through ingestion of infected colostrum and/or milk, or through inhalation of respiratory secretions. However, many studies also provide evidence that intrauterine infection may occur, though the extent and significance of this route is controversial. Embryos treated to IETS standards appear to pose very little risk of infection. SRLV have been detected in semen suggesting a potential source of transmission. However, such transmission has not been demonstrated to date. The application of control measures based on this information allows more efficient strategies to be developed which will reduce the rate of transmission.
Maedi-visna virus (MVV) seroprevalence associated with consumption of colostrum from seropositive ewes was investigated in 276 housed lambs from birth to 300 days-old. At birth, lambs were allocated to five experimental groups according to the maternal MVV-serological status, source and mode of feeding colostrum (bovine or ovine and bottle fed or suckled from the dam) and type of horizontal MVV-exposure (raised with the dam or separately with other lambs). The risk of being seropositive at 300 days-old was associated with feeding ovine colostrum from seropositive ewes and increased with intake of bottle-fed ovine colostrum and was higher in lambs separated from their dams and raised with other experimental lambs compared to lambs raised with their dams. Approximately 75-87% of ELISA-positive results in lambs that had ovine colostrum was attributable to colostrum itself. However, approximately only 16% of naturally raised and 29-61% of bottle-fed ovine colostrum lambs were ELISA-positive as a result feeding ovine colostrum. These results confirm that ovine colostrum from seropositive ewes can be a major source of MVV but its overall contribution to seroprevalence in natural conditions is relatively low, and shows that horizontal MVV transmission can be an important source of infection in new-born lambs.
Maedi visna virus and caprine arthritis encephalitis virus are closely related retroviruses that cause chronic inflammatory disease in small ruminants. The infections are characterised by insidious onset and slow progression. Diagnosis of infection is usually by serological testing. A variety of assays are available for this purpose, though the relative sensitivity and specificity of these assays has not been compared systematically. Here we review recent developments in laboratory diagnostic methods and their use in field diagnosis. The results suggest that a combination of ELISA and PCR might afford optimal detection of SRLV infection.
A three year long experimental study was carried out to investigate horizontal MVV-infection by PCR and ELISA, in 191 one year-old latxa dairy-sheep raised in two separate groups under low and high MVV-infection pressure, respectively. Sheep originated from a previous MVV-transmission study in lambs and seroprevalence among one year-old sheep in both groups was 15% approximately. The high infection-pressure group (H-group) consisted of 147 replacement ewes that joined a milk-producing, housed dairy-flock with 42-66% MVV-seroprevalence and the low infection-pressure group (L-group) were castrated males raised in a separate shed. In contrast to results obtained when infection was investigated in lambs, the overall degree of agreement between ELISA and PCR results was very good and there was some indication that it increased further as sheep became older. MVV-prevalence did not change in the L-group and increased to 57% in three year-old sheep in the H-group (p<0.001). Random effects logistic regression confirmed seroconversion was significantly higher in the H-group compared to the L-group and was highest during the year after the sheep were introduced in the dairy flock and did not increase with age as in previous studies using less sensitive antibody assays. The evidence that horizontal transmission can be very low in spite of prolonged close contact between infected and non-infected sheep is valuable for MVV-control purposes. Furthermore it highlights the need to investigate virus excretion dynamics in infected animals and animal to animal transmission to improve our overall understanding of horizontal MVV transmission in MVV endemic populations.
A recent large-scale experimental study showed that bottle-feeding ovine colostrum from seropositive ewes results in high MVV-seroconversion in lambs. In contrast, relatively few lambs that naturally suckled colostrum from seropositive dams seroconverted as a result of it. Furthermore, lambs fed uninfected bovine colostrum readily seroconverted when mixed with ovine-colostrum lambs indicating that horizontal MVV transmission between lambs was efficient. MVV-infection was further investigated in the same samples using two PCR tests targeting sequences in the long-terminal repeats (LTR) and POL MVV genes. PCR-tests confirmed previous serological findings. However, the LTR-PCR was more sensitive and allowed detecting infection earlier than the other tests, including 5-8% of new-born lambs from seropositive dams, providing more evidence that prenatal MVV-infection may be more important than considered. The degree of agreement between PCR and antibody tests in individual samples was low up to 6 months of age and moderate at 10 months-old. Nine percent of lambs were always PCR-negative but seroconverted and 19% of lambs were PCR-positive at least once and did not seroconvert. However, seroconversion was associated with increasing number of times lambs were PCR-positive and ovine colostrum-fed lambs were more frequently PCR-positive than other lambs. The significance of these findings in terms of MVV-infection, epidemiology and control is discussed.
Between 1997 and March 2004, the nervous form, or visna, of maedi-visna infection was diagnosed in 71 of 1631 sheep (4.35 per cent) examined in the Castilla y León region of Spain, of which 634 had shown nervous signs. The presence of the virus was confirmed by immunohistochemistry and in some cases by pcr on frozen-thawed or paraffin-embedded tissue samples. The main clinical signs were hindleg ataxia and paresis, but blindness or nystagmus were also observed. Thirty-three of the affected sheep (46.5 per cent) were two years old or younger. The affected sheep showed variable degrees of a non-suppurative meningoencephalitis, and immunohistochemistry identified positive cells in all cases, with no relation to the intensity of the inflammatory lesion.