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Infectious disease and red Wolf conservation: Assessment of disease occurrence and associated risks

  • Point Defiance Zoo & Aquarium

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Infectious diseases pose a significant threat to global biodiversity and may contribute to extinction. As such, establishing baseline disease prevalence in vulnerable species where disease could affect persistence is important to conservation. We assessed potential disease threats to endangered red wolves (Canis rufus) by evaluating regional (southeastern United States) disease occurrences in mammals and parasite prevalence in red wolves and sympatric coyotes (Canis latrans) in North Carolina. Common viral pathogens in the southeast region, such as canine distemper and canine parvovirus, and numerous widespread endoparasites could pose a threat to the red wolf population. The most prevalent parasites in red wolves and sympatric coyotes were heartworm (Dirofilaria immitis), hookworm (Ancylostoma caninum), and Ehrlichia spp.; several red wolves and coyotes were also positive for bacteria causing Lyme disease (Borrelia burgdorferi). Coyotes had a more species-rich parasite community than red wolves, suggesting they could harbor more parasites and act as a disease reservoir. Species identity and sex did not significantly affect parasite loads, but young canids were less likely to have heartworm and more likely to have high levels of endoparasites. Continued disease monitoring is important for red wolf recovery because low levels of genetic variability may compromise the wolves’ abilities to combat novel pathogens from closely related species, such as domestic dogs and coyotes.
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... The presence and density of hosts determines the chances of a parasite finding a suitable host, and thus the successful transmission of parasites (Morgan et al., 2004;Fox et al., 2013). Parasites in turn can limit population size, increasing the risk of stochastic extinctions in small populations (Morgan et al., 2005;Page, 2013;Brzeski et al., 2015). Understanding parasite transmission can enable management strategies, in species of conservation concern and livestock that may overlap with wildlife (Woodroffe, 1999;Walker and Morgan, 2014). ...
... The effect of parasites on individuals can depend on factors such as sex, age and reproductive stage (Debeffe et al., 2016;Lynsdale et al., 2017), which can be linked to parasite exposure or variation in host defences (Johnson et al., 2012) and the availability of resources (Hutchings et al., 2002). Parasite infection can limit population size and may contribute to population crashes, making small populations vulnerable to stochastic extinctions threatening the persistence of species of conservation concern (Woodroffe, 1999;Morgan et al., 2005;Page, 2013;Brzeski et al., 2015). Additionally, many parasites can infect both livestock and wildlife in areas where they overlap. ...
... Parasites impact the behaviour, fecundity and survival of host species, which can limit population size. This may make small or fragmented populations susceptible to extinction, threatening the persistence of vulnerable species (Brzeski et al., 2015;Page, 2013), or may reduce the productivity of livestock with economic implications for farmers (Morgan et al., 2013). Wildlife and livestock species often overlap grazing areas and thus spillover of parasites between wildlife and livestock is common. ...
Animal movement, behaviour and the transmission of parasites are closely linked to the environment in which animals are found. Mountain ecosystems are expected to be affected by climate change at a faster rate, and with implications for species such as the ungulate Alpine ibex (Capra ibex). These species are adapted to extreme conditions, thus understanding how they cope with their environment is important to estimate the effect of climatic changes. Biologging tools enable remarkable insights into the behaviour and movement of elusive species. However, the ease with which these data can be collected is in stark contrast to the difficulties in analysing and interpreting such large data sets. This thesis addressed: 1) the application of biologging tools using a domestic counterpart, African pygmy goats (Capra aegagrus hircus), specifically refining methods used to estimate behaviour and energy expenditure, and 2) measuring the behaviour, physiology and parasites of a mountain ungulate, Alpine ibex, in the face of climate change. I demonstrate that to accurately measure body acceleration when using collar-attached devices, the collar must be of an appropriate size and weight to reduce acceleration measured due to extraneous collar movement. Using these methods, I then demonstrate the use of tri-axial acceleration and magnetometry to classify the behaviours of domestic and captive Caprids. I refined random forest methods to enable analysis of data, predicting the slope of terrain for locomotion behaviours and demonstrating how individual split data better represents the ability of models to predict the behaviour of unobserved individuals. Model accuracy was high when using the same individuals to train and validate the model, but lower when predicting on individuals not used to train the models. Pygmy goat data was used to predict Alpine ibex behaviours with a similar accuracy. Using biologging tools, the interaction between the environment, energy expenditure and behaviours was then investigated. Using open-flow respirometry I measured the relationships between oxygen consumption and ambient temperature, and oxygen consumption and body acceleration when walking at different speeds and terrain slopes. These estimates were then applied, with the above behavioural classification methods, to estimate the daily behaviour and energy expenditure of pygmy goats in two enclosures. Activity levels were higher in a flat enclosure in warmer temperatures, but energy expenditure was higher in the enclosure that was sloped and measured at lower temperatures. These calculations show the importance of accounting for extrinsic factors and can be applied to free-ranging ungulates. To predict the parasite transmission of gastrointestinal nematodes in Alpine ibex, I adapted the Gloworm-FL model framework to account for seasonal elevational host movement. I demonstrated that host movement is more important than the elevational change in environmental conditions (temperature and precipitation), and that domestic sheep contribute significantly to parasites in this system. Alpine ibex are predicted to be exposed to the highest infection pressure in the Autumn, a critical time to gain body condition prior to winter and using projected climate scenarios suggested that although infection pressure is likely to increase, this may be moderated by Alpine ibex as they select areas with cooler temperatures. In response to climate change, Alpine ibex are likely to shift their range, within the constraints of their elevations, and alter their behaviour and movement to cope with warmer temperatures. I hypothesise that this, coupled with an increase in parasite transmission, will affect their over-winter survival and thus their population growth. Using the above methods and calculations of energy expenditure, the behaviour and energy expenditure of Alpine ungulates can be measured which will help us understand how these species will respond and cope with climatic changes. Overall, this work shows how to best apply biologging tools, and the interaction between the environment, behaviour and energy expenditure in the context of climatic changes.
... 10 Prior studies have identified disease exposure and mortality in both captive and free-ranging red wolves. 2,9 A survey of mortality in captive red wolves examined postmortem between 1997 and 2012 identified neoplasia and gastrointestinal disease as the most common causes of death in adult animals. 9 Infectious disease (primarily bacterial pathogens) contributed to 9% of adult mortality. ...
... 9 A recent analysis of infectious diseases affecting free-ranging red wolves identified exposure to ectoparasites (ticks, biting lice, mange mites), endoparasites (hookworm, heartworm), viral disease (canine distemper, canine parvovirus, rabies), and tick-borne disease (Lyme disease, ehrlichiosis, and Rocky Mountain spotted fever). 2 Prior determination that free-ranging red wolves are exposed to vector-borne organisms (VBOs) raises the question whether these pathogens affect the ex situ population. The goal of this study was to assess the prevalence of selected VBOs in captive red wolves to evaluate their potential as threats to species survival and to provide a baseline that may facilitate ongoing disease monitoring and the detection of emergent threats from such VBOs. ...
... were detected in 72% of sampled free-ranging red wolves, and at least one red wolf tested positive for Rocky Mountain spotted fever. 2 Closely related canids such as coyotes (Canis latrans), gray wolves (Canis lupus), and domestic dogs (Canis lupus familiaris) experience exposure, infection, or both to multiple VBOs at nonzero rates. [2][3][4]7 Alternatively, rather than lack of exposure or susceptibility, red wolves may be capable of clearing infection by these VBOs, or they may experience infection with blood pathogen levels below the detection thresholds of the referenced qPCR assays, which range from one to five pathogen DNA target copies. ...
The red wolf (Canis rufus) is a critically endangered North American canid, with surviving conspecifics divided between a captive breeding population and a reintroduced free-ranging population. The goal of this study was to assess the prevalence of selected vector-borne pathogens in captive red wolves. Whole blood samples were collected from 35 captive red wolves. Quantitative polymerase chain reaction (PCR) assays were performed on extracted DNA to identify infection by Trypanosoma cruzi and vector-borne organisms within the following genera: Anaplasma, Babesia, Bartonella, Ehrlichia, Mycoplasma, Neoehrlichia, Neorickettsia, and Rickettsia. All red wolves sampled were PCR-negative for all tested organisms. These pathogens are unlikely to constitute threats to red wolf conservation and breeding efforts under current captive management conditions. The results of this study establish a baseline that may facilitate ongoing disease monitoring in this species.
... Several carnivores have been described as heartworm definitive hosts in wildlife: coyote (Canis latrans); red fox (V. vulpes); grey fox (Urocyon cinereoargenteus) [5,11,12]; golden jackal (Canis aureus) [7,9,13]; red wolf (Canis rufus) [14]; European wildcat (Felis silvestris) [13]; and Eurasian otter (Lutra lutra) [13,15]. Data on heartworm infection in the grey wolf (Canis lupus), the closest wild relative of the domestic dog, are still scarce, having been reported only sporadically in Europe since 2001 [7,[16][17][18][19][20][21][22][23]. ...
... In addition, the size of adult nematodes from wolves was similar as reported in dogs (mean length: 25.5 cm) [3]. In contrast, studies on red foxes showed that the majority of female worms were small-sized immature individuals [5,14]. A fox-like pattern was revealed recently in the golden jackal, a canid currently spreading from the Balkans into central Europe, including northern Italy [14]. ...
... In contrast, studies on red foxes showed that the majority of female worms were small-sized immature individuals [5,14]. A fox-like pattern was revealed recently in the golden jackal, a canid currently spreading from the Balkans into central Europe, including northern Italy [14]. Overall, the similarity with dogs and the substantial difference with other wild canids, suggest that wolves are fully competent hosts of D. immitis and in the future may represent a complementary reservoir of this parasite, aside unprotected dogs. ...
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Background: Wild carnivores such as the grey wolf (Canis lupus), red fox (Vulpes vulpes) and golden jackal (Canis aureus) are recognized hosts of Dirofilaria immitis. However, few studies have focused on their actual role in the epidemiology of heartworm infection. This study describes the prevalence and distribution of D. immitis in wolves in a heartworm-endemic area in northern Italy where wolves have recently returned after long-time eradication, and investigates the fertility status of the collected adult nematodes. Methods: In the frame of a long-term wolf monitoring programme in northwestern Italy, 210 wolf carcasses from four provinces were inspected for the presence of filarioid nematodes in the right heart and pulmonary arteries. Female heartworms were measured, and their uterine content analyzed according to a previously described "embryogram" technique. Results: Three wolves, all originating from a single province (Alessandria), were positive for D. immitis (1.42%, 95% CI: 0.48-4.11%, in the whole study area; 13.6%, 95% CI: 4.7-33.3%, limited to the single province from which infected wolves originated). Mean intensity was 5 worms (range: 3-7) and the female worms measured 21-28 cm in length. Six out of 9 female worms harbored uterine microfilariae: 5 were classified as gravid; 1 showed a "discontinuous gradient"; and 3 were non-gravid. Conclusions: The present data show that heartworm infection is already prevalent in wolves that have recolonized the known heartworm-endemic area. Based on "embryogram" results, wolves were shown suitable heartworm hosts. Interestingly, investigated wolves appeared similarly exposed to heartworm infection as sympatric unprotected dogs (owned dogs that have never received any heartworm prevention treatment) sampled at the beginning of the wolf return process.
... Parasites have detrimental effects on host health and fitness (Soares, Gozzelino, & Weis, 2014), driving infectious disease (Simpson, Johnson, & Carver, 2016) and posing major conservation threats, particularly to endangered or isolated host species (Pedersen, Jones, Nunn, & Altizer, 2007;Wikelski, Foufopoulos, Vargas, & Snell, 2004). At the population level, high infection intensity can disrupt group dynamics and substantially limit population growth and size (Albon et al., 2002;Eira, Vingada, Torres, & Miquel, 2006;Watson, 2013), sometimes accelerating population crashes or elevating extinction risk (Brzeski et al., 2015;Gulland, 1992;Johnson et al., 2012). At the individual level, heavy burdens can be highly pathological, increasing risk of infectious disease and secondary illnesses (Beldomenico et al., 2008;Day, Graham, Read, & Kl, 2007), and stimulating immunopathology (Graham, Allen, & Read, 2005). ...
... Consequently, studies suggest that sex differences in infection exist because of differing optimal fitness strategies, mediated by competitive trade-offs between reproduction and self-maintenance, with males favoring paternity and females longevity (Folstad & Karter, 1992;Hamilton & Zuk, 1982;Hayward, 2013;Mills et al., 2009;Zahavi, 1975). Within a host population, juveniles, and juvenile males in particular (Clutton-Brock & Pemberton, 2004;Wilson, Grenfell, Pilkington, Boyd, & Gulland, 2004), often experience the heaviest parasite loads (Brzeski et al., 2015;Jones, Crawley, Pilkington, & Pemberton, 2005). This may be due in part to the fact that immune function is not yet fully developed in maturing individuals (Simon, Hollander, & Mcmichael, 2015), as well as potential trade-offs arising between growth and immunity (Medley, 2002;Tschirren & Richner, 2006). ...
... While parasites have been implicated in the regulation of certain populations of red grouse Lagopus lagopus scotica (Hudson, Dobson, & Newborn, 1998), Arctic charr (Knudsen et al., 2002), and Svalbard reindeer Rangifer tarandus platyrhynchus (Albon et al., 2002), studies describing the frequency of parasite-induced mortality and identifying the individuals within populations with the highest risk of parasite-induced mortality are exceptionally rare. In addition, while studies have shown that infection intensities within wild populations are consistently increased in certain groups, for example, juveniles (Brzeski et al., 2015) and males (Craig et al., 2006;Harrison et al., 2010;Klein, 2004), links between these groups and elevated mortality risk have rarely been made. Arguably in many wild vertebrate populations, individual mortality is likely to be due to a synergy of factors, for example, interactions between infection and weight loss, hormone differences, and poor diet. ...
... Infatti, questi potrebbero agire da "sentinelle" della comparsa e/o la diffusione della parassitosi in aree indenni, o addirittura da reservoir, in particolar modo laddove i fenomeni di interazione domestico--selvatico sono frequenti e le condizioni climatiche consentono ai vettori lunghi periodi di attività. Attualmente, gli ospiti definitivi descritti nella fauna selvatica sono il coyote, la volpe rossa e grigia (rispettivamente, Canis latrans, Vulpes vulpes, Urocyon cinereoargenteus) (Wixsom et al., 1991;Criado et al., 2000), il lupo (Canis lupus, Canis rufus) (Brzeski et al., 2015), lo sciacallo dorato (Canis aureus) (Tolnai et al., 2014) e la lontra euro--asiatica (Lutra lutra) (Torres et al., 2004). I casi di dirofilariosi descritti in Europa nella volpe e nello sciacallo dorato hanno evidenziato una prevalenza relativamente bassa (rispettivamente 2,9% e 7,4%) ed una microfilariemia sporadica associata ad una predominanza di infestazioni con pochi adulti in sede cardiaca (Gradoni et al., 1980;Marconcini et al., 1996;Magi et al., 2008;Tolnai et al., 2014). ...
... Questi studi suggeriscono che volpe e sciacallo non rappresentano, almeno nelle aree relative agli studi, ospiti ideali per il completamento del ciclo biologico del nematode. In altri carnivori selvatici, risultati più recenti dagli Stati Uniti (Brzeski et al., 2015) descrivono una prevalenza più elevata (45%) di dirofilariosi cardiopolmonare nel lupo rosso (Canis rufus) e nel coyote (7%) (Wixsom et al., 1991). Nel lupo europeo la prima infestazione è stata segnalata nel 2001 da Segovia in Spagna con la presenza di un'unica filaria adulta (a seguito di 47 necroscopie eseguite su lupi provenienti dal nord--est della Spagna), mentre in Italia risale al 2007 (Pascucci et al., 2007) in una regione del centro--sud in cui la dirofilariosi è presente solo in maniera sporadica. ...
La filariosi cardiopolmonare è una patologia causata dalla Dirofilaria immitis e colpisce primariamente il cane. I carnivori selvatici come lupo (Canis lupus) e volpe (Vulpes vulpes) rappresentano ospiti potenzialmente validi per il completamento del ciclo vitale del parassita, tuttavia esistono pochi studi che ne descrivano il ruolo epidemiologico effettivo. Lo scopo del nostro studio è quello di analizzare la capacità riproduttiva delle filarie adulte isolate da lupi del nord Italia dal 2016 al 2019, e di inquadrare la situazione epidemiologica di volpe e lupo in una zona endemica del Piemonte confrontandola con quella del cane descritta da altri autori.
... To keep the analyses at a reasonable level of complexity, the following pathogen groups were considered: bacteria (including rickettsia), viruses (including prions), ectoparasites (mites, ticks, lice and fleas), and protozoa. Only one fungus (Batrachochytrium dendrobatidis) and two parasitic helminths (meningeal worm Parelaphostrongylus tenuis and heartworm Dirofilaria immitis) were considered, based on their proven capacity to affect populations of wild amphibians (Skerratt et al. 2007), cervids (Lankester 2010) and canids (Brzeski et al. 2015), respectively. ...
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Invasive alien species (IAS) can act as vectors for the introduction of pathogens in ecosystems and their transmission to threatened native species (TNS), leading to biodiversity loss, population reductions and extinctions. We assessed pathogens potentially occurring in a set of IAS in the Southern Cone of South America and identified TNS potentially vulnerable to their effects. Also, we assessed how risk analysis systems proposed or adopted by national authorities in the study region value the importance of pathogens. We identified 324 pathogens in the selected IAS, which could potentially affect 202 TNS. Wild boar (Sus scrofa) was the IAS with the largest number of pathogens (91), followed by domestic dog (Canis familiaris) (62), red deer (Cervus elaphus) (58), rock dove (Columba livia) (37), American vison (Neovison vison) (18), European hare (Lepus europaeus) (17), common starling (Sturnus vulgaris) (12), common slider (Trachemys scripta) (6), and American bullfrog (Lithobates catesbeianus) (2). Most TNS were in the “vulnerable” IUCN category, followed by “endangered” and “critically endangered” species. Bacteria were the most frequently represented pathogens (112), followed by ectoparasites (78), viruses (69), protozoa and other (65). The direct effects of IAS on native wildlife are beginning to be addressed in South America, and their potential impact as pathogen spreaders to native wildlife has remained largely unexplored. Risk analysis systems associated with the introduction of IAS are scarce in this region. Although the existing systems contemplate hazard analyses for the co-introduction of pathogens, they underestimate the potential impact of diseases on TNS. Conservation efforts in the region would benefit from systems which give pathogen risk a relevant place, and from government agencies promoting targeted disease surveillance in IAS and wildlife.
... We used mixed-effects modeling to contextualize genetic diversity within the broad range of factors that may influence infection severity in YNP wolves. Input data were derived from annual observa- (Almberg et al., 2015;Brzeski et al., 2015) and observation year (Stahler et al., 2013). As numerous wolves changed pack membership across years, we fitted these variables as partially crossed random intercepts. ...
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Population genetic theory posits that molecular variation buffers against disease risk. Although this “monoculture effect” is well supported in agricultural settings, its applicability to wildlife populations remains in question. In the present study, we examined the genomics underlying individual‐level disease severity and population‐level consequences of sarcoptic mange infection in a wild population of canids. Using gray wolves (Canis lupus) reintroduced to Yellowstone National Park (YNP) as our focal system, we leveraged 25 years of observational data and biobanked blood and tissue to genotype 76,859 loci in over 400 wolves. At the individual level, we reported an inverse relationship between host genomic variation and infection severity. We additionally identified 410 loci significantly associated with mange severity, with annotations related to inflammation, immunity, and skin barrier integrity and disorders. We contextualized results within environmental, demographic, and behavioral variables, and confirmed that genetic variation was predictive of infection severity. At the population level, we reported decreased genome‐wide variation since the initial gray wolf reintroduction event and identified evidence of selection acting against alleles associated with mange infection severity. We concluded that genomic variation plays an important role in disease severity in YNP wolves. This role scales from individual to population levels, and includes patterns of genome‐wide variation in support of the monoculture effect and specific loci associated with the complex mange phenotype. Results yielded system‐specific insights, while also highlighting the relevance of genomic analyses to wildlife disease ecology, evolution, and conservation.
... Understanding the relationship between inbreeding and disease is critical to the conservation of small or fragmented populations, in which the probability of inbreeding is elevated (Pertoldi et al. 2007, Smith et al. 2009, Brzeski et al. 2015. Our results illustrate the elevated risk that both endemic and emerging vector-borne diseases (WNV and-in nestlings-Plasmodium) can pose for inbred individuals and populations, underscoring the need to buffer small populations against infectious disease. ...
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Infectious diseases can have devastating impacts on wildlife populations and are of particular concern for small, inbred populations. Identifying specific pathogens that are linked to morbidity and mortality in inbred individuals is a priority for the conservation of small populations, but opportunities to examine them in the wild are rare. Here, we examined the relationship between heterozygosity and infectious disease in American crows (Corvus brachyrhynchos), a species that engages in close inbreeding, focusing on three pathogens common in Davis, California, USA: West Nile virus (WNV), Plasmodium spp. (avian malaria), and Campylobacter jejuni. We found that low heterozygosity at a panel of 33 microsatellite loci was associated with two vector‐borne infectious diseases (WNV and avian malaria), but not with infection by the bacterial gut pathogen C. jejuni. Reasons for this association with vector‐borne pathogens are unclear, but might include behavioral factors and immunological differences associated with inbreeding. Overall, these data are consistent with the idea that inbred individuals may be more susceptible to both novel and endemic vector‐borne pathogens, underscoring the importance of protecting genetic diversity within populations and buffering small populations against infectious diseases.
... The low vaccination coverage concept utilised in conserving endangered species can also protect a core group of individuals during a disease outbreak (Prager et al. 2011;Vial et al. 2006). The prophylactic use of vaccines can increase a population's resistance to a disease, especially when herd immunity has been attained (Aguirre et al. 2002;Brzeski et al. 2015;Fine 1993). Inoculating animals can also be utilised as a remedial treatment for individuals that have been exposed to a particular pathogen, see Hofmeyr et al. (2000). ...
Health and disease is important for the African Painted Dog as episodic disease events have contributed to severe population declines and localised extinctions of free-ranging populations. Similar risks also extend to captive populations. Vaccination is an integral part of controlling infectious disease in wildlife populations as it decreases disease incidence and lowers transmission rates. Vaccines developed for domestic animals are routinely used to prevent the risk of disease in wildlife species. But, despite widespread use, little is known about how effective these vaccines are for threatened species. This disparity requires investigation and is a focus of this research. Factors that can influence a vaccine’s efficacy relate to the characteristics of the vaccine itself or to the host that is being vaccinated. In this study the latter is examined, with host-specific factors targeting duration of immunity, as well as, the degree of stress individuals’ experience when immobilised. This study demonstrates that the inactivated Parvac™ vaccine designed to mitigate the risk of canine parvovirus is safe to use in the African Painted Dog. The duration of immunity is however disproportionately shorter than that for domestic dogs, with a modification of the inoculation schedule recommended to extend protective immunity in the African Painted Dog. In its assessment of the stress response, the study shows that individual animals were able to adapt to the short term stress imposed by capture and handling. This was determined by the primary stress mediator, cortisol, by invasive and non-invasive means. Through repeated monitoring of cortisol across successive capture events a chronic stress response was also characterised. Social stress is deemed to be a contributing factor in the chronic stress response, with the frequency of stressors rather than their origin being of greater importance. The results demonstrate that where there are consistently high cortisol concentrations protective immunity is reduced. Examining the immunogenicity of vaccines in protecting species against infectious disease and the effects of stress are both areas that have the potential to refine or develop existing methodologies and alternative strategies for better animal health and welfare practices. Through its examination of these interlinked themes this study contributes to better disease management practices and improved assessment of the effect that research practices have on animal welfare.
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El conocimiento de los parásitos presentes en animales silvestres de un área determinada nos puede dar un panorama del estado general y conservación de éstos como también del grado de alteración del sitio donde se encuentran. La carga parasitaria nos ayuda a evaluar el grado de infección por algunos parásitos en heces, sangre y orina. Este trabajo tuvo como objetivo determinar la prevalencias y las cargas parasitarias en heces de coyotes de dos zonas distintas del Área de Protección de Flora y Fauna Médanos de Samalayuca, Chihuahua, México, evaluar la temporada de mayor riesgo de presencia de formas parasitarias en las heces y comparar las distintas técnicas para el diagnóstico coproparsitoscópicos utilizadas. La colecta de heces se realizó en dos áreas del APFFMS, el área 1 con intervención humana y el área 2 menos perturbada. Se colectaron 180 heces a lo largo de septiembre 2018 a octubre del 2019, 110 provenientes del área 1 y 70 del área 2, las mismas fueron analizadas por las técnicas de Centrifugo-Flotación en NaCl, Formalina, la técnica de sedimentación de Hoffman y recuento de huevos por gramo en cámaras de McMaster, para determinar la intensidad parasitaria media y la prevalencia de parásitos. La prevalencia para el área 1 fue de 52% y para el área 2 fue 57%, heces colectadas en el área 1 presentaron mayor carga parasitaria en tres géneros parasitarios que se encontraban en los rangos considerados altos, sin embargo no presentaron diferencias significativas (p=0,009). En cuanto a la temporada de mayor riesgo, la temporada fría demostró tener 2,17 más probabilidades de encontrar heces con formas parasitarias en ellas, con un intervalo de confianza de 95%. En cuanto al uso de las técnicas la de Hoffman demostró ser la más efectiva a la hora de diagnosticar positivos, sin embargo al comparar las tres técnicas cada una de ellas resultó ser efectiva a la hora de diagnosticar formas parasitarias distintas (oocystos, huevos livianos y huevos pesados). Concluyendo, se demostró que las heces de coyote, puede contener un gran número de agentes parasitarios de vi importancia tanto para la salud pública como animal y que la utilización de diferentes técnicas permite una mejor evaluación parasitológica. El monitoreo rutinario y más diversificado sería oportuno para mejorar las políticas de manejo de la APFFMS y así poder implementar acciones de prevención y control de estos agentes, principalmente en las áreas de mayor concurrencia de personas. En un estudio de prevalencia parasitaria se hace importarte considerar la temporada en la que la colecta fue realizada, teniendo en cuenta que esta puede influenciar en la eliminación de formas parasitarias. Palabras clave: cánido, cestodos, fauna silvestre, nematodos, protozoarios.
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Resumen Los lineamientos para el uso de especies de mamíferos de vida silvestre en la investigación con base en Sikes et al. (2011) se actualizaron. Dichos lineamientos cubren técnicas y regulaciones profesionales actuales que involucran el uso de mamíferos en la investigación y enseñanza; también incorporan recursos nuevos, resúmenes de procedimientos y requisitos para reportes. Se incluyen detalles acerca de captura, marcaje, manutención en cautiverio y eutanasia de mamíferos de vida silvestre. Se recomienda que los comités institucionales de uso y cuidado animal (cifras en inglés: IACUCs), las agencias reguladoras y los investigadores se adhieran a dichos lineamientos como fuente base de protocolos que involucren mamíferos de vida silvestre, ya sea investigaciones de campo o en cautiverio. Dichos lineamientos fueron preparados y aprobados por la ASM, en consulta con profesionales veterinarios experimentados en investigaciones de vida silvestre y IACUCS, de quienes cuya experiencia colectiva provee un entendimiento amplio y exhaustivo de la biología de mamíferos no-domesticados. La presente versión de los lineamientos y modificaciones posteriores están disponibles en línea en la página web de la ASM, bajo Cuidado Animal y Comité de Uso: ( Recursos adicionales relacionados con el uso de animales de vida silvestre para la investigación se encuentran disponibles en (
Parasites are thought to provide a selective force capable of promoting genetic variation in natural populations. One rarely considered pathway for this action is via parasite-mediated selection against inbreeding. If parasites impose a fitness cost on their host and the offspring of close relatives have greater susceptibility to parasites due to the increased homozygosity that results from inbreeding, then parasite-mediated mortality may select against inbred individuals. This hypothesis has not yet been tested within a natural vertebrate population. Here we show that relatively inbred Soay sheep (Ovis aries), as assessed by microsatellite heterozygosity, are more susceptible to parasitism by gastrointestinal nematodes, with interactions indicating greatest susceptibility among adult sheep at high population density. During periods of high overwinter mortality on the island of Hirta, St. Kilda, Scotland, highly parasitised individuals were less likely to survive. More inbred individuals were also less likely to survive, which is due to their increased susceptibility to parasitism, because survival was random with respect to inbreeding among sheep that were experimentally cleared of their gastrointestinal parasite burden by anthelminthic treatment. As a consequence of this selection, average microsatellite heterozygosity increases with age in St. Kildan Soay sheep. We suggest that parasite-mediated selection acts to maintain genetic variation in this small island population by removing less heterozygous individuals.
Tools for performing model selection and model averaging. Automated model selection through subsetting the maximum model, with optional constraints for model inclusion. Model parameter and prediction averaging based on model weights derived from information criteria (AICc and alike) or custom model weighting schemes. [Please do not request the full text - it is an R package. The up-to-date manual is available from CRAN].
Canine and Feline Infectious Diseases is a practical, up-to-date resource covering the most important and cutting-edge advances in the field. Presented by a seasoned educator in a concise, highly visual format, this innovative guide keeps you current with the latest advances in this ever-changing field. 80 case studies illustrate the clinical relevance of the major infectious disease chapters.
Present range of Canis latrans in the US Southeast is outlined, a distribution facilitated by, or locally a direct result of releases by man. Spread, which has been notable since 1972, has been expedited by the merging of local populations. -P.J.Jarvis