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The effect of Amblyomma variegatum on liveweight gain of cattle in Zambia
Abstract
The effect of the tick Amblyomma variegatum Fabricius on liveweight gain (LWG) on yearling cattle over 16 weeks was evaluated under quasi-natural conditions. Early in the exposure period when animals may have been in a state of suppressed metabolism, the effect of tick feeding on LWG was negligible. Overall, however, the difference in LWG between tick-free and tick-infested groups of cattle was 4.95 kg after 16 weeks. This difference between the groups was used to estimate a lower LWG of 48-63 g due to each engorging female tick.
... The loss in weight attributed to each en-gorged female A. variegatum was 55 g (or about 70 g if the atypical animal is withdrawn from the analysis). This result is in agreement with those obtained in Zambia by Pegram et al. ( 1989 ) and Pegram and Oosterwijk ( 1990): 46-61 g and 48-63 g liveweight loss per engorged female, respectively. It contradicts, however, the result of Stachurski et al. (1988 ) in Guadeloupe, which noted that A. variegatum did not cause any significant weight loss in Creole zebu. ...
... The existence of a time lapse between tick infestation and the occurrence of weight loss owing to them, has already been observed with A. variegatum (Pegram and Oosterwijk, 1990). This was also noted in this experiment. ...
... The N animals probably then suffered the repercussions of the important infestation during the preceding months. Pegram and Oosterwijk (1990) reported an interval of 4-6 weeks between the infestation and the occurrence of the consequent loss in weight. They suggested the existence of an anorectic effect of ticks to explain this phenomenon. ...
The effect of natural tick infestation on the liveweight gain (LWG) of male Gudali zebu cattle was studied throughout a year by comparing the performances of two herds, one of which was submitted to weekly acaricidal treatment and the other was left untreated against ticks. Six species of ticks were identified on the untreated animals: Amblyomma variegatum, Boophilus decoloratus, Rhipicephalus lunulatus, Rhipicephalus turanicus, Hyalomma nitidum and Hyalomma marginatum rufipes. Most of the losses observed in the untreated herd during the rainy season were due to A. variegatum, and the loss in LWG was estimated to be 55-76 g per engorged female A. variegatum. The infestation also leads to wounds and to lesions of dermatophilosis. There was an interval between the peak infestation by A. variegatum and the appearance of weight loss owing to them. The control of ticks on the Gudali zebu in Adamawa, during the months of high infestation by A. variegatum adults, is economically profitable. On the other hand, the performances of the two herds during the dry season were similar, showing that infestation by larvae and nymphs of A. variegatum has no impact on the zebu LWG, and that tick control during that period is not profitable.
... Ticks are obligate, intermittent, ectoparasites of terrestrial vertebrates, and all species are exclusively haematophagous in all feeding stages (Klompen et al. 1996). Blood loss due to feeding of adult female ticks can result in reduction of live weight gain of cattle (Pegram and Oosterwijk 1990), dry matter intake and milk yield (Jonsson et al. 1998). Approximately 10% of the currently known tick species act as vectors of a broad range of pathogens such as those that cause theileriosis, heartwater, babesiosis and anaplasmosis. ...
... acridum and I. fumosoroseus) on R. sanguineus and found that unfed larvae and nymphs were more sensitive to fungal infection than engorged ones and unfed adult females were less sensitive than engorged females. The ability of fungi to kill both immature and mature stages of ticks is important as major tick-borne diseases are transmitted by the younger stages such as larvae and nymphs while engorging females cause blood loss and loss of productivity (Pegram and Oosterwijk 1990;Kettle 1995). ...
In the absence of commercially viable and environmentally friendly options, the management of cattle ticks is heavily dependent on the use of chemical acaricides. Due to recent advances in production, formulation and application technology, commercial fungus-based biological pesticides (myco-insecticides, myco-acaricides) are becoming increasingly popular for the control of plant pests; however, they have not been used against animal ectoparasites. The literature clearly demonstrates that entomopathogenic fungi are pathogenic to ticks under laboratory conditions. Pasture applications have also shown promise while experiments on topical application have had variable results. These results suggest that major research hurdles still exist especially for the latter. Although literature on ticks and their interactions with entomopathogenic fungi exists, there is not a clear understanding on how this can be influenced by the microenvironment of the cattle skin surface. This paper critically reviews pathogen, tick target and host skin microenvironmental factors that potentially affect pathogenicity of the applied entomopathogen. Factors influencing the route of infection for topically applied myco-acaricides are also reviewed. Major researchable constraints and recommendations are identified and prioritized. In particular, there is the need for basic studies to understand the interaction of entomopathogenic fungi with the components of the skin microenvironment, to identify suitable strains, and to develop improved formulations to overcome the various challenges.
... Ticks prefer areas on an animal's body where the skin is thin and blood flow plentiful, like the inguinal region and external genital area (Hurtado and Giraldo-Ríos 2018). This can be observed in the case of A. variegatum which has a preference for the udder of livestock leading to drastically reduced milk production, serious wounds (Stachurski 2000) and impaired growth (Pegram and Oosterwijk 1990). ...
Ticks are important disease vectors affecting animal health and causing substantial economic loss, especially in the tropics and subtropics. To examine the tick burden of cattle and associated risk factors for tick infestation, ticks were collected from 388 cattle within five regions in Ghana. Most of the cattle were males (50.3%) and generally older than 3 years (65%). Of the animals sampled, 2187 ticks were collected with a mean tick burden of 5.6 ticks per cattle, and the average tick burden on the udder/scrotum being significantly higher than in the anal region (Generalized Linear Mix Model [GLMM], p = 0.01197). The tick species identified were predominantly Amblyomma variegatum (42.6%) and Hyalomma rufipes (26.2%). High proportions of cattle examined were found to have A. variegatum infesting the udder/scrotum. Furthermore, H. rufipes infested mostly the anal region compared to other examined body parts (OR 14.8, 95% CI 8.6–25.4, p < 0.001). Using the GLMM, tick abundance was found to be significantly higher in cattle older than 3 years. The tick burden in the udder/scrotum was higher than that from the chest and leg/thigh of the cattle (GLMM, p < 0.05). The tick burden at the anal region was also significantly higher than the leg/thigh and chest. This study indicates that the preferred attachment sites of ticks on cattle are species-dependent and effective treatment with acaricides should take into consideration the udder/scrotum and anal regions as well as prioritizing older cattle.
... These diseases diminish cow's growth rate, fertility, milk production and quality hides which results in significant economic losses to livestock breeders. (Pegram and Oosterwijk, 1990;Jongejan and Uilenberg,1994). ...
... Ticks are known to cause lowered productivity ( Sajid et al., 2007), mortality (Niyonzema and Kiltz, 1986) and can transmit Theileria (T.) spp., Babesia (B.) spp., Coxiella (C.) burnetii, Anaplasma (A.) spp., Rickettsia (R.) spp., and several viruses that causes deadly diseases ( Taylor et al., 2007;Bakheit et al., 2012; Estrada-Peña and de la Gortazar et al., 2014;CDC, 2016). An adult female tick can cause blood loss that can result in reduction in live weight gain of cattle (Pegram and Oosterwijk, 1990) (Jonsson et al., 1998). Finally, ticks may cause immunosuppression of host (Inokuma et al., 1993;Ferreira and Silva, 1998) that may facilitate the attack of other microorganisms resulting in disease. ...
... Ticks are considered as the most important ecto-parasites of dairy and pet animals. They have been incriminated as voracious blood suckers, causing direct damages to hides (Jongejan and Uilenberg, 2004), lowered productivity in terms of weight gain (Pegram and Oosterwijk, 1990), milk yield (Sajid et al., 2007), and increased mortality due to tick borne diseases (Niyonzema and Kiltz, 1986). Tick control program is focused on large scale indiscriminate use of synthetic organophosphates (OP), synthetic pyrethroids (SP), amidines and macrocyclic lactones (ML) (Kemp et al., 1999;Bianchi et al., 2003;Rodrıǵuez-Vivas et al., 2007) leads to the development of resistance in ticks which is considered as the main hindrance for successful pest and vector control program in livestock globally (FAO, 2004;Graf et al., 2004). ...
... They are distributed all over the world except the frozen regions, comprising very successful groups which have developed a wide spectrum of adaptations for host usage and environmental tolerance (Abdigoudarzi et al. 2009). They are probably the most harmful ectoparasites of domestic animals including cattle and wild animals, being of very substantial veterinary importance which cause a large economic losses in livestock production through blood sucking, weight loss, biting, skin damage, toxins injected and the transmission of a variety of viral, bacterial and protozoan diseases (Morel 1989, Pegram & Osterwijk 1990, Wall & Shearer 2008, Moges et al. 2012Adams et al. 2015). Tick-borne diseases affect 80% of the world's cattle population (Marcelino et al. 2012) (Kabair et al. 2011. ...
A survey was conducted from January 2015 to December 2015 in 12 provinces in Iraq to identify and classify the seasonal distributions of the major hard ticks species (Ixodidae) found on cattle in the north, middle and south of Iraq. A total of 17,156 adult hard ticks were collected from 3,812 indigenous cattle. Sampling was repeated from the same provinces every month to determine the seasonal diversity. Five species belonging to two genera (Hyalomma and Rhipicephalus) were identified; the most abundant ticks were Hyalomma anatolicum 41.72%, Rhipicephalus turanicus 24.60%, Hyalomma turanicum 16.65%, Hyalomma scupense 13.26% and Rhipicephalus annulatus 3.67%. There were differences between each province related to the environment as well with the previous studies.
... Tick-borne diseases, namely, East Coast Fever, anaplasmosis, babesiosis and cowdriosis have been reported to affect the optimal livestock productivity in East African region (McCosker et al., 1993). Apart from acting as vectors for TBDs, ticks have been recognized as important ectoparasites of livestock by sucking blood, causing local necrosis which results in low quality hides (Jongejan and Uilenberg, 2004), secondary bacterial infections (Ambrose et al., 1999), lowering productivity in terms of weight gain (Pegram and Oosterwijk, 1990) and milk yield (Sajid et al., 2007), increasing susceptibility to the other diseases (De Castro, 1997), dermatosis, toxicosis and paralysis (Solomon Gebre and Kaaya, 1998). Based on the number of hosts required to complete their development during their life cycle, ticks can be classified as one-host, two-host and three-host ticks (Walker et al., 2003). ...
... Other significant economic damage accredited to this tick is reduction in live weight gain. Pegram and Oosterwijk (1990) estimated a reduction of 48 to 63 g for each engorging female A. variegatum tick in central Zambia. It has also been shown that for every ten engorging females of this tick, there is a decrease in live weight gain of 20 kg over a period of 3 months (Pegram et al. 2000). ...
The objective of the study was to determine the acaricidal properties of Bobgunnia madagascariensis (Desv.) J.H. Kirkbr. and Wiersema (Leguminosae) against adult Amblyomma variegatum (Fabricius) ticks, using Tephrosia vogelii Hook.f. (Leguminosae) as a positive control. Plant extracts of both were prepared using methanol, acetone and chloroform as extraction solvents. Methanol leaf extracts of T. vogelii (0.014 g) and methanol fruit extracts of B. madagascariensis (0.0062 g) gave the highest mean extraction weights among the plant parts and solvents used. In free contact bioassays, only methanol extracts of the bark and leaf material of T. vogelii and methanol fruit extracts of B. madagascariensis produced 100 % mortality of A. variegatum ticks in 24 h. The acaricidal activity of methanol leaf extracts of T. vogelii persisted for up to 8 days while that of fruit extracts of B. madagascariensis persisted for only 6 days. In topical application bioassays, the toxicity of T. vogelii and B. madagascariensis extracts was found to be significantly different at 95 % confidence level, with B. madagascariensis extracts (LD50 0.030 w/v) being more toxic than T. vogelii extracts (LD50 0.555 w/v). This study has shown that plant extracts of B. madagascariensis and T. vogelii extracts have significant in vitro acaricidal activity against A. variegatum ticks and can thus be considered as alternatives for tick control. Further research is however required on persistence, safety and the required application rates.
... Ticks are considered as the most important ecto-parasites of dairy and pet animals. They have been incriminated as voracious blood suckers, causing direct damages to hides (Jongejan and Uilenberg, 2004), lowered productivity in terms of weight gain (Pegram and Oosterwijk, 1990), milk yield (Sajid et al., 2007), and increased mortality due to tick borne diseases (Niyonzema and Kiltz, 1986). Tick control program is focused on large scale indiscriminate use of synthetic organophosphates (OP), synthetic pyrethroids (SP), amidines and macrocyclic lactones (ML) (Kemp et al., 1999;Bianchi et al., 2003;Rodrıǵuez-Vivas et al., 2007) leads to the development of resistance in ticks which is considered as the main hindrance for successful pest and vector control program in livestock globally (FAO, 2004;Graf et al., 2004). ...
Discriminating concentrations (DCs) of malathion, coumaphos, fenvalerate and fipronil were determined to monitor acaricide resistance in field conditions. The LC99 values with 95% confidence interval for malathion, coumaphos, fenvalerate and fipronil were 5126.8 (5011.5-5240.7), 131.0 (120.4-142.5), 2257.5 (2198.1-2318.4) and 6.2 (5.87-6.55), respectively. The narrow confidence intervals in LC50 and LC99 of adult immersion test (AIT) and larval packet test (LPT) affirming the homogeneity of IVRI-I line. Variation in LPT based LC50 and LC99 values of malathion (55.9ppm) and coumpahos (28.4ppm) compared to those obtained in AIT indicating that larvae were more susceptible to these chemicals. The DCs for malathion, coumaphos, fenvalerate and fipronil against adults were determined as 10253.6, 262.0, 4515.0 and 12.4ppm while against larvae the values were 111.8, 56.8, 4014.0 and 9.6ppm, respectively. The working efficiency of DCs was successfully tested in field tick isolates. Establishment of country specific DCs of commonly used insecticides for monitoring of resistance in field ticks is emphasized for establishing tick control strategies.
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... Apart from acting as vectors for pathogens, ticks have been recognized as important ectoparasites of livestock (Hezron et al. 2012). They are bloodsuckers, causing local necrosis which results in lowquality hides (Jongejan and Uilenberg 2004), lowered productivity in terms of weight gain (Pegram and Oosterwijk 1990) and milk yield (Sajid et al. 2007). ...
The aim of the present study was to evaluate the serum concentration of cardiac troponin I (cTnI) in camels with tick infestation as a marker of potential myocardial injury and its prognostication. The effects of acid-base and electrolyte balance and haematobiochemical profiles were also investigated. Twenty-three camels (Camelus dromedarius) with tick infestation and suffering from anorexia, incoordination of movement, unsteady gait, recumbency, opisthotonus, anaemia and reduced production were examined. Ticks were visible, deeply embedded in the skin over the whole body, especially under the neck and around the udder or testis. Of the camels, 15 recovered after treatment and 8 did not. Blood samples were collected from the diseased camels on the day of admission to our clinic. Blood samples were also collected from 12 healthy camels and were used as controls. The mean serum concentration of cTnI in the camels with tick infestation was 1.7 ± 1.6 ng/ml compared to 0.03 ± 0.02 ng/ml in the controls. The mean serum concentration of cTnI in those camels that recovered was 0.36 ± 0.53 ng/ml compared to 3.0 ± 1.1 ng/ml in the camels that did not. Venous blood gas alterations included an increase in partial pressure of carbon dioxide and decreases in partial pressure of oxygen and oxygen saturation. Haematological parameters involved decreases of red blood cells, haemoglobin and haematocrit and increases in the mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. Biochemical parameters included significant elevations in the serum activity of aspartate aminotransferase, creatine kinase and alkaline phosphates. Other biochemical alterations observed were decreases in total protein and albumin and increases in globulin and glucose concentrations. In conclusion, the data of this study suggest the possibility of using cTnI as a biomarker for cardiac injury in camels with tick infestation and for the prognosis of the outcome in the treated animals. Generally, values above 1.0 ng/ml were considered bad prognostic indicators.
... Apart from acting as vectors for diseases (TBDs), ticks have been recognized as important ectoparasites of livestock. They are bloodsuckers, causing local necrosis which results to lowquality hides [2], secondary bacterial infections [7], lowered productivity in terms of weight gain [8] and milk yield [9]. Studies have shown that ticks of the genera Rhipicephalus and Amblyomma which are the most important in TBD transmission are distributed in almost all cattle keeping areas in Tanzania [10,11]. ...
This study aimed at determining the extent of tick infestations in extensively grazed cattle and assess the efficacy of Ecotix® acaricide (2.5% high cis cypermethrin) in Mvomero district in Tanzania. A total of 1200 Tanzanian short horn Zebu (TSHZ) from two farms in two villages were qualitatively assessed for tick infestations and 40 animals (grouped in 10s from each farm) were separated in their herds and quantitatively examined to establish the tick load. The animals were grouped in treatment regime groups (TxRG 1, 2, 3, and 4), TxRG 1 being the control group was treated with water. Ecotix® was applied on day 0 for TxRG 2, days 0 and 7 for TxRG 3 and days 0, 7 and 14 for TxRG 4 and tick load was monitored for 28 days.
All the animals examined were infested with ticks. The identified ticks were Rhipicephalus appendiculatus (55%), Amblyomma variegatum (18%), R. (Boophilus) microplus (12.9%), R. (B) decoloratus (7.1%), R. evertsi evertsi (4.4%) and R. composites (2.6%). The overall mean (mean ± SEM) tick density on day zero was 63 ± 30 ticks per animal (ranging from 20–160). The mean tick density on day zero was 44.6 ± 25.4, 74.6 ± 30.3, 55.0 ± 26.2 and 77 ± 33.5 for groups one, two, three and four respectively. Post-treatment quantitative assessment of tick burden revealed that the TxRG 1 animals maintained a tick load throughout the study period. A significant decrease in tick load in animals in groups TxRG 2, 3 and 4 (P=0.0001) with increasing frequency of Ecotix® application was recorded. There was however no significant difference in tick reduction between TxRG 3 and 4 (P=0.0986). Thus TxRG 3 would be sufficient for the monthly tick treatment and with this regime, the farmer would save up to 2.5 USD per animal during six months of dry season.
The study revealed a high tick infestation among the TSHZ kept in extensive grazing systems in Mvomero district and that when treated with Ecotix® as pour-on preparation using a two application regime per month, the tick control strategy was effective.
... In West Africa, Amblyomma variegatum (Fabricius) is considered the most harmful tick species (Mattioli et al. 1997; Knopf et al. 2002; Farougou et al. 2007). This tick impairs animal growth (Pegram et al. 1989; Pegram and Oosterwijk 1990; Stachurski et al. 1993) and exacerbates dermatophilosis (Plowright 1956). Moreover it transmits to ruminants the causative agent of the deadly disease cowdriosis or heartwater (Ehrlichia ruminantium). ...
Traditional systems account for 95 % of the livestock produced in Burkina Faso. Tick infestation hampers livestock productivity in this area. However, little information exists on tick-control practices used by livestock farmers. We interviewed 60 stockbreeders working in traditional farming systems to obtain the first data on tick-control practices. Sixteen farmers (27 %) did not use conventional practices: seven removed ticks by hand or plastered cattle with dung or engine oil; nine farmers treated cattle with crop pesticides. Forty-four farmers (73 %) used mainly synthetic pyrethroids (SP; either alphacypermethrin or deltamethrin in 20 and 18 farms, respectively) and occasionally amitraz (N = 6). Intervals between treatments varied significantly depending on the chemical used: most farmers using crop pesticides (100 %), amitraz (100 %) or alphacypermethrin (80 %) adjusted tick-control to tick-burden, whereas farmers using deltamethrin tended more to follow a tick-control schedule. Perception of tick-control effectiveness significantly varied among practices: tick-control failures were more frequently reported by farmers using alphacypermethrin (55 %) than by those using either other conventional acaricides (17 %) or crop pesticides (0 %). We investigated whether this could indicate actual development of SP-resistance in cattle ticks. First, using the larval packet test technique, we confirmed that the computation of LC(50) and LC(90) was repeatable and remained stable across generations of the Rhipicephalus (Boophilus) geigyi Houndé laboratory strain. We then collected from the field fully-engorged female R. geigyi to evaluate the SP-resistance relative to the Houndé reference strain. We did not detect any case of SP-resistance in the field-derived R. geigyi ticks.
... In terms of TBD of cattle in Zambia, Heartwater, is surpassed in importance only by ECF/ CD and Anaplasmosis, caused by the T. parva and A. marginale group of organisms, respectively. In Zambia, Heartwater is regarded as a serious disease and many commercial farmers sustain great economic losses when they slacken their normal tick control practices [46,47,87]. Moreover, Heartwater is becoming increasingly important because of the changing agricultural practices in Zambia, including the frequent use of imported exotic breeds of livestock to improve productivity, extension of intensive livestock farming into areas that are ecologically marginal for vector survival and increasing movement of livestock between Heartwater free and endemic areas. ...
Tick-borne diseases occurring in Zambia are assuming more importance as they continue to be a major economic problem not only in Zambia, but in many parts of Eastern, Southern and Central Africa. The current control methods, which include the use of toxic acaricides to kill ticks, and the virulent sporozoite infection and treatment method have limitations. Recombinant vaccines, currently in their experimental stages, offer hope for the future. The use of acaricides is hampered by the development of acaricide resistance and live vaccines are dependent on cold chain facilities, which are a formidable obstacle in the poorly developed infrastructure in parts of Zambia where the vaccine is most needed. Amidst these drawbacks are the results of the recent research on parasites and vector recombinant vaccines which promise to circumvent these problems. The history, current status and attitudes regarding the control of these diseases, taking into account their complexity, are reviewed. The establishment of the well-designed Central Veterinary Research Institute (CVRI) and Japanese International Cooperation Agency (JICA) sponsored veterinary school, both have a potential for high quality research, with access to a wealth of specimens a veritable goldmine of research material. It is thus hoped that this review will stimulate the desire to maximize the value of the tick and tick-borne disease research in both Zambia and the international research community.
... Ticks are a major global problem as ectoparasites of livestock. Blood loss due to feeding of adult female ticks can result in reduction of live weight gain of cattle (Pegram and Oosterwijk, 1990), dry matter intake, and milk yield (Jonsson et al., 1998). Samish and Rehacek (1999) discussed the potential of biological control of ticks and concluded that biological pesticides based on entomopathogenic fungi was one of the most promising options. ...
Experiments were conducted to determine if Metarhizium anisopliae isolates which are capable of growth at cattle surface temperatures could produce pathogenicity to Boophilus microplus in laboratory and field studies. The diurnal temperature fluctuation on the surface of cattle was monitored. The temperature tolerance of M. anisopliae isolates (ARSEF3297 and IMI386697) was determined and their pathogenicity to B. microplus compared at a standard bioassay temperature (28 degrees C) and at a temperature similar to the cattle surface (31-35 degrees C). The effect of the two isolates on the B. microplus population on cattle under field conditions was determined. The temperature of the fore udder, rear udder, ribs and neck regions of the mixed Holstein cattle fluctuated between 30 and 35 degrees C, in a similar pattern to the prevailing environmental temperature. However, wider fluctuations were obtained on the ears (28-35 degrees C) and spine (30-41 degrees C). The colony radius of both isolates declined as temperature increased, however, the growth of IMI386697 was five times greater than ARSEF3297 at 34 degrees C. At 28 degrees C, the pathogenicity of both isolates to B. microplus was similar, however, at 31-35 degrees C, IMI386697 was more pathogenic than ARSEF3297. Both isolates reduced the B. microplus population on cattle in comparison to the control formulation. However, IMI386697 (8.5+/-0.64 ticks/animal) produced a greater reduction in tick numbers than ARSEF3297 (19.1+/-0.64 ticks/animal). M. anisopliae was re-isolated from 8.9% of the ticks collected from IMI386697 treated cattle as compared to 2.8% of ticks from ARSEF3297 treated cattle.
This is an Open Access Journal / article distributed under the terms of the Creative Commons Attribution License (CC BY-NC-ND 3.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. All rights reserved. The acaricidal effects of crude ethanolic extract of the aerial parts of Leucas lavandulifolia Sm. against Rhipicephalus (Boophilus) annulatus was studied. Different dilutions of the extract such as 2.5, 5, 10, 15 and 20 per cent were tested against R (B.) annulatus by using adult immersion test (AIT). The crude ethanolic extract of L. lavandulifolia caused a significant dose-dependent increase in adult tick mortality with maximum mortality of 95.83 per cent at the highest concentration tested. Though the inhibition of fecundity at 20 per cent concentration was 97.6 per cent, hatching of eggs was not affected by any of the concentration studied. The LC50 value of the extract against R.(B.) annulatus was 2.87 per cent.
Heartwater (or cowdriosis) is a tick-borne disease caused by Ehrlichia ruminantium, an obligatory intracellular bacterium of the order Rickettsiales, transmitted by several ticks of the genus Amblyomma. The organism is genetically highly variable which prevented until now the development of efficient vaccines. The disease is enzootic in sub-Sahelian Africa and in some Caribbean islands. It affects domestic and wild ruminants, the susceptibility to cowdriosis varying greatly between breeds and species: African wildlife shows mainly asymptomatic infections; local cattle breeds are generally protected due to enzootic stability; and introduced cattle breeds and small ruminants, even in enzootic regions, are usually susceptible to heartwater and can suffer high mortality rates. Cowdriosis is characterized by a sudden and acute fever followed by nervous, respiratory, and gastrointestinal symptoms and by hydrothorax and hydropericardium during postmortem examination. In West Africa, the only vector is Amblyomma variegatum, present in areas where pluviometry is higher than 500 mm. Therefore, animals of a high proportion of the Sahelian region are usually not infested by the tick and not infected by the bacterium. They are thus susceptible when introduced in southern parts of the Sahel or in the subhumid neighboring areas of the West African countries, for example during transhumance. Tetracyclines are effective drugs to treat heartwater when administered before occurrence of the nervous symptoms. Various vaccines have been tested, and are still developed, but, up to now, none of them showed enough effectiveness against all the field strains of E. ruminantium to allow its marketing. Prevention is therefore mainly achieved by drastic vector control or, on the contrary, acquisition of enzootic stability following tick infestation combined with tetracycline treatment as soon as hyperthermia occurs.
Increasing costs of tick control have necessitated a complete re-assessment of its economic impact. There are two main approaches to studies on production economics. Some researchers advocate a “systems approach” in which all production traits and their interactions are monitored simultaneously, whilst others claim that studies must produce specific data on selectively identified components in the system which can then be used in process/simulation type models.
Studies were carried out in Zambia using a farming systems approach to quantify the effects of tick control on traditionally managed Sanga cattle. It seems that this decision was justified, because it is evident from the results that the determinants of the effects of tick control are extremely complex.
Overall herd productivity, i.e. outputs of milk and weaner calf per livestock unit carrying capacity, was about 25% higher in a tick-free herd. However, the annual cost of control in 1988 at ZK286.26 per livestock unit was greater than the increase in value of the products at ZK175.48 per livestock unit carrying capacity.
From this study, the intensive tick control in this system is not justified in the absence of serious tickborne disease. However, the analysis of various interactions indicate that limited seasonal tick control of adults from November to April would be economically viable. Calves should not be treated until they are 3 months of age.
The objective of this study was to estimate economic losses in terms of milk production caused by tick infestation in dairy buffaloes (Bos bubalus bubalis) of Punjab (Pakistan). To this end, six hundred Nili-Ravi buffaloes infested with Hyalomma ticks (Acari: Ixodidae) were selected and divided into two equal groups viz; A & B. The animals of group A were treated with various doses of 5% cypermethrine pour-on (Cipermetriven, Ivan Labs, Spain) while those of group B were treated with propylene glycol (Propandiol - (1, 2), Merck) as a sham treatment. Average milk production (L) and butter fat (%) was recorded before and after treatment in order to calculate post-treatment increase in these parameters (if any). An average daily increase of 1.15L in milk yield per animal with 1.31% more fat was observed in acaricide- treated animals. A dose-dependent effect of acaricide was found on the number of ticks as well as milk production and fat. The results provided a baseline data for further research on economic impact of tick nuisance to the smallholder dairy farming systems of Pakistan.
This study investigated the comparative efficacy of ivermectin and cypermethrin pour-on, for the treatment of Hyalomma anatolicum (a.) anatolicum infestations in bovines. For examining acaricidal efficacy, 480 ticks were exposed in vitro to graded doses of both the acaricides and in vivo efficacy was examined in 360 tick-infested bovines treated at the recommended doses of ivermectin (IVM) and cypermethrin (CYM) pour-on. The comparative quantitative assessment of tick burden was done on days 0, 5, 10, 15, and 20 after treatment using "finger counting." The results of the tick survival assay indicated both compounds were effective in vitro against H. a. anatolicum. The arc transformed mean surviving ticks, 24 h post immersion, was 2.66 and zero in groups treated with the highest dilutions of IVM and CYM, respectively. At 15 days post-treatment, the CYM pour-on showed a higher in vivo efficacy (no surviving ticks) compared to IVM (mean of 20 surviving ticks). A single dose of CYM and IVM was found effective for 20 and 15 days post-treatment, respectively. Additionally, a questionnaire was used to gather information from 30 small holder dairy farms on the farmer's approach toward the control of ticks. The majority (90%) of respondents were using acaricides incorrectly along with poor husbandry practices on their farms. Overuse of IVM in the tested area of Pakistan may be the reason the IVM is not as effective as expected. These results provide useful tools for the decision making in tick control, as well as providing the basis for testing the findings on provincial and national levels in future studies.
Three different tick control policies were tested in groups of traditionally managed Sanga cattle in the Central Province of Zambia over a period of 3 years. One group was given strategic tick control using 12 pyrethroid acaricide spray applications between the onset and the end of the wet season (October to March). The productivity of this herd was compared with that of a group with no tick control and a group under an intensive tick control regimen of spraying every week in the wet season and every 2 weeks in the dry season (36 applications per year). The highest output was associated with intensive tick control, followed by strategic control and then no tick control policies. However, when the costs of tick control were taken into account, the strategic tick control policy produced the best economic result, followed by the intensive and then the no tick control policies. Neither the strategic nor the intensive tick control policy was sufficient to prevent the transmission of East Coast fever (ECF) infection when this disease was introduced to the area.
The effect of tick infestations on liveweight gain (LWG) was assessed by comparison of weight changes in flumethrin-treated N'Dama and Gobra zebu cattle (16-20 months old) with respective control groups submitted to natural tick challenge over 1 year. Flumethrin was applied monthly, fortnightly or weekly. Preventive treatments against anaplasmosis, babesiosis and trypanosomosis were given. Mortality rate was recorded and post-mortem examinations carried out. In both treated and control animals, significantly fewer Hyalomma spp. and Amblyomma variegatum were found on N'Dama than on Gobra zebu cattle. Both breeds are equally susceptible to Rhipicephalus senegalensis infestation. Total annual tick burdens did not cause significant differences in LWG between acaricide-treated and control cattle in either breeds. LWG was also not affected during or after the annual peak of tick infestation (composed mainly by A. variegatum and R. senegalensis). Equally-high mortality (35%), due to unidentified causes, was recorded in acaricide-treated and control Gobra cattle; mortality in N'Dama cattle was 7.5%. In both breeds, about the 90% of mortality occurred at the end of the dry season. Breed differences in tick burden confirm previous results. If tick-borne infections do not influence LWG or mortality, then it is concluded that intensive tick control is not justifiable in Gambian livestock.
The efficiency of strategic and strategic/selective applications of flumethrin spray formulation for controlling ticks were assessed, respectively, in two groups of fourteen N'Dama cattle (Group S and Group S/S) by comparison of the number of feeding ticks with thirteen untreated N'Dama cattle (Group U) over a period of 11 months (June 1996 to April 1997). During the expected peak of tick abundance, acaricide was applied fortnightly on the whole body in animals in Group S and only on the most infested body areas in cattle in Group S/S. Weight changes and skin lesions, directly associated with tick attachment, were recorded in cattle in the three groups. The costs of the two tick control schemes were estimated. Maximum level of ticks, all species together, feeding on cattle was observed in the rainy season. Both in Group S/S and Group S, cattle carried a lower (P < 0.001) number of feeding ticks than animals in Group U over the whole study period. Percentage of tick control, over the entire period of tick investigation, was satisfactory in both acaricide-treated groups, reaching 61.2 and 75.2% in Groups S/S and S, respectively. However, the proportion of control varied according to tick species or genus. Significantly lower prevalence of skin lesions was observed on the ano-genital and udder region in cattle in Group S/S (P < 0.05) and Group S (P < 0.01) in comparison with cattle in Group U. Mean amount of acaricide solution used and relative estimated cost of treatment in cattle in Group S/S were, respectively, 25- and 14-fold lower than those in cattle in Group S. At the end of the study, animals in Groups S/S and S were, respectively, 7.2 and 15.9 kg heavier than animals in Group U. The difference was statistically significant (P < 0.02) only between Groups S and U. However, the efficiency, low cost and derived benefits of the strategic/selective acaricide application scheme indicated that it might be the most cost effective.
In sub-Saharan Africa, tick infestation and tick-borne infections together with tsetse-transmitted trypanosomosis arguably constitute the main parasitological disease complex constraining livestock production. Resistance to tick attack and tick-borne micro-organisms (TBMs) varies among different breeds of cattle. The magnitude of losses due to these parasites is related to an extent to the degree of breed resistance. Generally, zebu (Bos indicus) cattle possess a higher resistance to ticks and TBMs than European (Bos taurus) cattle. The host's immune system would appear to be the single most important factor that regulates this resistance. This paper reports on the main effector immune mechanisms governing resistance against ticks and TBMs. The cellular immune response appears more effective and stable than humoral immunity in modulating resistance to ticks and TBMs. Similarities between the immune mechanisms employed by trypanotolerant N'Dama (B. taurus) cattle, when infected with trypanosomes, and those elicited by tick bites and TBMs seem to exist, particularly at the skin level in the early phases of parasitic invasion. Moreover, there is evidence that in the N'Dama breed, resistance against ticks per se also has a genetic basis. Therefore, the N'Dama appears to be a unique breed in that it exhibits resistance to several parasitic diseases and/or infections, including helminths, when compared to other cattle breeds in West Africa. It is concluded that the multi-parasite resistant traits of the N'Dama breed should be exploited in those areas where trypanosomosis, ticks and tick-borne diseases constrain animal production. This should be of benefit for low-input farming systems where the use of chemicals for prophylaxis and therapy is limited by their relatively high cost. Additionally, the potential contribution of multiple disease resistant N'Dama cattle should be considered in crossbreeding programmes with exotic dairy breeds for increasing milk production in West Africa.
Studies in Cameroon and Burkina Faso examined the invasion process of cattle by adult Amblyomma variegatum Fabricius (Acari: Ixodidae) ticks. Nearly all the ticks picked up in the pasture during grazing were found on the limb ends, near the hooves, where they temporarily attached. Then when the cattle lay down, the ticks moved from the feet towards the predilection sites, where they attached definitively. Many ticks disappeared during this displacement. All the female ticks and approximately 70% of the males were thus unable to attach to the predilection sites as long as the pioneer males had not attached and started to produce attraction-aggregation-attachment pheromones. Nevertheless, A. variegatum females and males attached to the feet in similar numbers during grazing, whether the cattle were already infested or not, indicating that stimuli originating from the hosts are powerful enough to attract both sexes. After attachment of the pioneer males, the number of ticks that successfully reached the predilection sites increased. However, even on infested animals, 40-50% of A. variegatum ticks found near the hooves after the grazing periods disappeared during the night following their capture. When moving from the temporary attachment sites towards the final ones, one-third of the ticks changed the individual host. Considering this two-stage infestation process, it is suggested that a targeted tick control, using a foot-bath, might greatly reduce cattle infestation. In particular, it could be effective in traditional herds, with animals grazing permanently during the day, lying down only once back in the night pen.
The association between mean daily weight gain, Theileria parva infections, clinical East Coast fever and other possible determinants of weight gain were examined in a longitudinal observational study that was conducted in cohorts of female calves from five agro-ecological zone (AEZ)-grazing strata. The strata were upper-midlands (UM) 1 zero-grazing, UM 1 open-grazing, UM 2 zero-grazing, UM 4 zero-grazing and UM 4 open-grazing. In total, 225 calves on 188 smallholder dairy farms were visited within the first 2 weeks of life and thereafter at biweekly intervals up to the age of 6 months between March 1995 and August 1996. During each visit, the calves were weighed and other calf-management practices in the farm during the visit such as housing, feeding and tick control also were recorded. Other events such as morbidity and mortality between or during the visits were also recorded. The overall mean daily weight gains were 0.24-0.29 kg (S.D.=0.17-0.22 kg) and were lower than the recommended targets for smallholder farms of 0.40-0.50 kg. The major tendency in variability of daily weight gains was due to visit-to-visit variation (especially in calves >3 months old). Differences in mean daily gains were associated with AEZ-grazing strata and calf-level factors that included breed of calf, calf sickness, incidence of ECF, feeding of milk, concentrate feeds and minerals and interaction between calf age and AEZ-grazing strata (P<0.05). ECF and other calf sicknesses exerted a temporal effect on calf-growth at the height of illness and immediately after; calves later recovered the lost growth except where other factors such as poor calf nutrition prevailed. Improvement in calf-growth in Murang'a District is achievable and extension services should continue to target individual-calf-level management practices.
Entomopathogenic fungal isolates of Arachnid origin were assessed for their ability to produce mortality and inhibit egg hatching in Boophilus microplus with the aim of selecting an isolate for development into a myco-acaricide for control of cattle ticks. The ability of the most promising isolate to target developmental stages of more than one tick species and the optimum concentration of fungal inoculum to be used for future studies were determined. Metarhizium anisopliae was the most pathogenic of the three fungal species tested on B. microplus, producing shorter average survival times (ASTs) for engorged adults (AST = 5.2 +/- 0.1 days) and larvae (AST = 9.3 +/- 0.4 days), and a longer average hatching times (AHT; AHT = 19.8 +/- 0.5 days) in comparison to Simplicillium lamellicola and Paecilomyces farinosus. In comparative studies on two tick species with similar life cycles, M. anisopliae produced a shorter AST in engorged adult B. microplus (AST = 8.8 +/- 0.3 days) than Rhipicephalus sanguineus (AST = 10.3 +/- 0.3 days). M. anisopliae was pathogenic to larvae of B. microplus (AST = 7.7 +/- 0.4 days), however, had no effect on larvae of R. sanguineus (AST = 14.6 +/- 0.3 days) as the AST of this treatment was similar to its untreated control (AST = 14.1 +/- 0.4 days). M. anisopliae lengthened the AHTs in both B. microplus (AHT = 16.4 +/- 0.3 days) and R. sanguineus (AHT = 16.7 +/- 0.3 days) in comparison to the controls. The ASTs of engorged adult B. microplus treated with M. anisopliae shortened as the concentration was increased from 1 x 10(7) to 5 x 10(8) conidia/ mL. A further increase in concentration, 1 x 10(9) conidia/mL (AST = 10.2 +/- 0.4 days) did not shorten or lengthen the AST in comparison to 5 x 10(8) conidia/mL (AST = 9.4 +/- 0.3 days).
The effect of the tick Boophilus microplus on the liveweight of Bos indicus x B. tauvus steers was investigated using three levels of infestation during summer 1980, autumn-winter 1980 and summer 1981. Mean losses in liveweight per engorged female tick during each of the three periods were 0.72,0.47 and 1.52 gper tick respectively. The 1980 estimates were significantly lower (P < 0.05) than that in summer 1981, and the losses were independent of tick density. The loss per tick was unaffected by a supplement of molasses and urea in the autumn-winter period. Compensatory growth of those steers whose earlier growth was retarded by poor nutrition or ticks was investigated by keeping all the steers tick-free during spring. The previous medium and high tick groups gained 5-6 kg per animal more than the low group. Non-supplemented animals recovered all of their 14 kg disadvantage compared with the supplemented group. Mean tick survival rates varied from 9% in summer 1980 to 25% in autumn and 2% in summer 1981. They were reduced at higher densities but were unaffected by the nutritional supplement. The large variation in losses in liveweight per tick on these animals on the same pastures at different times suggests that differences in published estimates are frequently due to animal variation rather than to nutrition, cattle breed or environment. Economic thresholds were calculated for a range of effects of ticks and of chemical control costs. With a mean loss of 0.6 g per tick and 1983 dipping costs of $A1.35, the economic threshold is 158 ticks engorging per day per animal, assuming a kill of 97 %.
Tick populations were observed on Ankole (Sanga type Bos indicus x Bos taurus) cattle at monthly intervals over periods of 2–3 years in 4 ecological zones (Gatumba (830-m alt., 789-mm rain); Gitega (1671-m alt., 1122-mm rain); Kirundo (1420-m alt., 1076-mm rain) and Gihofi (1260-m alt., 1225-mm rain)) of Burundi, Central Africa. Concurrently, observations were made on the development and survival of Rhipicephalus appendiculatus in pastures at each location. Ticks were also counted on cattle in a fifth, high altitude zone (Ijenda, 2191-m alt., 1549-mm rain) for a period of 2 years. Rainfall was monomodal at all sites and fell between September and May. The species composition and total numbers of ticks infesting cattle in the 5 ecological zones varied. The most common species recorded were R. appendiculatus, Boophilus decoloratus and Amblyomma variegatum. The highest average number of adult females of the above species completing engorgement daily was 29 R. appendiculatus at Kirundo, 13 B. decoloratus at Ijenda and A. variegatum at Gitega. The regions differed slightly in their overall level of tick infestation, as measured by the average numbers of adult female ticks of all species engorging daily, i.e. Kirundo (34), Gatumba (27), Gitega (26), Ijenda (21) and Gihofi (11). Adults of A. variegatum exhibited the strongest seasonal pattern of feeding, with peaks early in the wet season. Non-climatic factors were apparently important in determining the relative numbers of A. variegatum in different regions. Development times of the free-living stages of R., appendiculatus in pastures varied between locations, taking 3 weeks for engorged larvae, 4–7 weeks for nymphs and 6–9 weeks for oviposition and egg development. Engorged larvae and nymphs suffered the least mortality while egg hatching was reduced in the dry season. Fifty percent of unfed larvae survived 1.5–3 months, nymphs 3–5 months and adults 16 months. Parasitic ticks completed engorgement more successfully when attached in preferred sites on the host's body.Computer simulations were used to estimate the proportional reduction in numbers of R. appendiculatus from dipping strategies with different timing, duration and efficiency. Strategies of 3-months duration, with the start timed to coincide with the period of adult feeding activity, were economically the most efficient. Computer simulations suggested that the annual cattle migration from the highlands to the lowlands in the dry season was important in limiting the size of tick populations. These results were taken into account when designing a policy to make the best use of the country's resources.
Field trials were carried out during 1982-86 in two different ecotypes in central Zambia to determine the impact of tick control on the liveweight gain (LWG) of cattle. During the first 2 years of the trial a diamidide acaricide (Amitraz) sprayed at weekly intervals caused periodic depression in LWG in young animals. Thereafter a pyrethroid acaricide (cypermethrin) was used. During the 1984-85 tick season infestations of 50-120 adult Amblyomma variegatum Fabricius in untreated animals caused significant reductions in LWG. From the differences in LWG between treated and untreated cattle, the induced loss in LWG was estimated at 46-61 g per engorged female A.variegatum.
In ecological studies in central Zambia, both climate and ecotype affected population dynamics of tick species. Below average rainfall for several years caused a suppression in numbers of Rhipicephalus appendiculatus Neumann adults. Reduction in rainfall leading to changes in grazing patterns is thought to have been responsible for an increase in numbers of Amblyomma variegatum Fabricius adults in a grassland habitat. There were reasonable correlations between numbers of each tick species on individual hosts over 1 year old. However, there were no relationships between numbers of ticks and bovine lymphocyte antigens (BoLA).
The effects of the bont tick Amblyomma hebraeum on the productivity of cattle need to be quantified in order to design economically optimal control programs. Liveweight gains (LWGs) of three groups of Africander steers, maintained in the same pasture and exposed to zero, medium or high numbers of larvae, nymphs and adults of the tick, were measured. Larvae and nymphs had no significant effect on LWG but adults had a large, statistically significant effect (P less than 0.05). The tick-free group had an average LWG of 20 kg more than the heavily infested group after 3.5 months. No mortality was recorded from ticks or tick-borne diseases during the experiment. There was no relationship between the number of engorging adult female ticks counted and loss of LWG of individual animals. The latter suggests that exposure to ticks as well as engorgement by female ticks causes losses. The loss per adult female that completed engorgement was estimated, by relating the LWGs of individual animals to their tick infestations, to be 4 +/- 2 g per adult female tick. An alternative estimate, made by comparing the average LWG and tick infestations of each treatment group, was equal to 10 +/- 4 g. This latter estimate includes the effect of challenge (and rejection) as well as tick feeding and so was accepted as giving the best estimate. Screw-worm fly (Chrysomya bezziana) struck an average of 7.5% of the cattle infested with ticks in any week but the effects on the productivity of the cattle were minimized by immediate treatment. There was a significant, positive correlation between the incidence of screw-worm fly strike and the numbers of adult ticks counted on the experimental animals. The results provide data for calculating losses caused by A. hebraeum in different parts of its geographical range.
In southern Africa, Amblyomma variegatum Fabricius is characterized by a strict seasonal activity. Experiments were carried out to determine whether a diapause mechanism regulates this seasonality. Engorged A. variegatum females were exposed to controlled laboratory conditions or natural field conditions at different times of the year. Females exposed in a natural environment in September‐October (short day) had significantly longer pre‐oviposition periods than females exposed from November to March. The season in which the previous instar fed had no apparent effect on the engorgement or pre‐oviposition periods of the females. Furthermore, artificial changes in photoperiod during and after female engorgement had no significant effects on pre‐oviposition periods.
It is tentatively concluded that the unfed female is the responsive stage to photoperiodic changes which induce diapause. Diapause could be terminated and oviposition induced by exposing females to a short period of chilling (18 O C for 48 h). It is concluded that a morphogenetic diapause mechanism exists in A. variegatum , which is probably induced by short day responses and terminated following rainfall and a concomitant decrease in soil temperature. The diapause, which occurs in females which fed early in the season, causes a delay in oviposition and therefore effectively synchronizes the life‐cycle to ensure that eggs and larvae occur at a climatically favourable period.
This experiment was designed to measure the effects of infestation by B. microplus on cattle and to separate the effects of reduced food intake ("anorectic effect") from those due to the remaining factors of tick infestation ("specific effect"). Hereford cattle kept on a high-quality diet were studied over a treatment period of 11 weeks with the tick-infested animals being infested regularly with equal larval doses for each animal.
Ectoparasites considered in this review are the parasitic insects as well as mites and ticks. The role of host nutrition in host defense, the role of protein and vitamin A, the need for vitamins of the B-complex, and the role of lipids and minerals are discussed. Wherever necessary the author is critical of inadequate methods or interpretations that may not be justified. Research has shown that subtle changes occur in the malnourished animal that may not become apparent until it is infested with a parasite. Moreover, it now seems clear that the standard recommendations for vitamin intake may in some cases not be adequate to aid the host in defense against parasitism.