Pathogen exposure in endangered island fox (Urocyon littoralis) populations: Implications for conservation management

Clifford, Deana L.; Mazet, Jonna A. K.; Dubovi, Edward J.; Garcelon, David K.; Coonan, Timothy J.; Conrad, Patricia A.; Munson, Linda

doi:10.1016/j.biocon.2006.04.029

Cited by 86 publications

(61 citation statements)

References 63 publications

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“…Examples of species that exhibit the Allee effect and suffer from fatal diseases include the endangered African wild dog Lycaon pictus [4,5,8] and the island fox Urocyon littoralis [1,7]. Studies of systems that exhibit the Allee mechanism seem to be focused on the role of the Allee effect at small population densities.…”

Section: Resultsmentioning

confidence: 99%

Fatal disease and demographic Allee effect: population persistence and extinction

Friedman

Yakubu

2012

Journal of Biological Dynamics

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If a healthy stable host population at the disease-free equilibrium is subject to the Allee effect, can a small number of infected individuals with a fatal disease cause the host population to go extinct? That is, does the Allee effect matter at high densities? To answer this question, we use a susceptible-infected epidemic model to obtain model parameters that lead to host population persistence (with or without infected individuals) and to host extinction. We prove that the presence of an Allee effect in host demographics matters even at large population densities. We show that a small perturbation to the disease-free equilibrium can eventually lead to host population extinction. In addition, we prove that additional deaths due to a fatal infectious disease effectively increase the Allee threshold of the host population demographics.

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Section: Resultsmentioning

confidence: 99%

Fatal disease and demographic Allee effect: population persistence and extinction

Friedman

Yakubu

2012

Journal of Biological Dynamics

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“…As an example, the emergence of a welldocumented CAV outbreak in island foxes (Urocyon litoralis) may have occurred through the interspecies passage of domestic dogs viruses introduced by the previously infected sympatric populations of ferrets (Spilogale gracilis amphiala). CAV mortality was observed in free-living silver foxes (Vulpes vulpes), with high incidence of diseases especially in young individuals (Clifford et al, 2006).…”

Section: Resultsmentioning

confidence: 99%

Adenoviruses of canine and human origins in stool samples from free-living pampas foxes (<italic>Lycalopex gymnocercus</italic>) and crab-eating foxes (<italic>Cerdocyon thous</italic>) in São Francisco de Paula, Rio dos Sinos basin

et al. 2015

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The spread of enteric viruses of domestic animals and human beings to wild species can be facilitated by the resistance of these viruses on the environment and their ability to be transmitted by water and contaminated food. The health status of the populations of pampas foxes (Lycalopex gymnocercus) and crab-eating foxes (Cerdocyon thous) is largely unknown and the landscapes occupied by these animals in southern Brazil have been threatened by human occupation and expansion of agriculture. In this work, the search of genomes of human and canine adenoviruses in feces from these wild carnivores was used to track the dissemination of domestic animals and human pathogens to the free-living populations in a wildlife reserve located in southern Brazil. This was performed by virus-specific differential real-time polymerase chain reactions (qPCR) on stool specimens, avoiding capture and additional stress to the animals. Genus-specific conventional reverse-transcriptase PCR (RT-PCR) was complementarily performed aiming the detection of enteroviruses (EV) and rotaviruses (RV) on these same samples. HAdV genomes were found on 14 out of the 17 (82.35%) stool samples analysed, whereas CAV was found co-infecting 5 of these samples. RV genomes were detected on 7 of the 17 samples (41.18%) and all samples were negative for EV. The results point to the dispersion of HAdV and RV at a high rate to these species of South American wild carnivores, which can be an effect of growing anthropisation of the habitat of these animals.Keywords: Lycalopex gymnocercus, Cerdocyon thous, adenovírus, rotavirus, enterovirus. Adenovírus de origens canina e humana em fezes de graxains (Lycalopex gymnocercus) e cachorros-do-mato (Cerdocyon thous) de vida livre em São Francisco de Paula, bacia do Rio dos Sinos ResumoA disseminação de vírus entéricos de animais domésticos e seres humanos para espécies selvagens pode ser facilitada pela resistência desses vírus no ambiente e sua capacidade de ser transmitida por água e alimentos contaminados. O estado de saúde das populações de Graxains-do-campo (Lycalopex gymnocercus) e Cachorros-do-mato (Cerdocyon thous) é em grande parte desconhecida e as paisagens ocupadas por estes animais no sul do Brasil têm sido ameaçadas pela ocupação humana e a expansão da agricultura. Neste trabalho, utilizou-se a pesquisa de genomas de adenovírus humanos (HAdV ) e caninos (CAV-1 e -2) em amostras fezes desses carnívoros selvagens com vistas a diagnosticar a disseminação de patógenos de animais domésticos e seres humanos às populações de vida livre em uma reserva de vida selvagem, localizado no sul do Brasil. Foram realizadas reações em cadeia da polimerase diferenciais e em tempo real (qPCR) de adenovírus específicos em amostras de fezes, evitando a captura e estresse adicional para os animais. PCRs gênero-específicas convencionais com transcrição reversa prévia (RT-PCR) foram ainda realizadas visando a detecção de enterovírus (EV) e rotavírus (RV) nestas mesmas amostras. Genomas de HAdV foram encontrados em 14 a 17...

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“…However, all SCA foxes tested had antibodies reactive against CPV, and CPV appears to be endemic on all the Channel Islands (except possibly San Miguel Island), as indicated by the consistently high prevalence of antibodies (Clifford et al, 2006). In the face of such high antibody prevalence, and the high disappearance rate across all age classes during the decline (an epidemiologic feature that is not typical of CPV infections in an endemic region [Barker and Parrish, 2001]), a parvovirus epidemic would be unlikely.…”

Section: Discussionmentioning

confidence: 96%

“…The lack of mortality in west-end foxes was likely because of a lack of exposure to the virulent strain due to the geographic deterrent of the isthmus. The high prevalence of antibodies reactive against CDV after the decline suggests recent exposure to CDV across the population (Clifford et al, 2006). Although fox antibodies reactive against CDV also reacted against PDV, PDV is not endemic in this region, and no epidemic was noted in the carefully monitored marine mammals on SCA rookeries during this time (F. Gulland, pers.…”

Section: Discussionmentioning

confidence: 99%

“…Positive antibody titers $8 were considered indicative of previous CDV exposure. This test cutoff for island foxes was based on replicate testing of samples (n526 replicates) and performance of the Cornell CDV VNT on serum from vaccinated foxes (Clifford et al, 2006). Archived frozen plasma (serum not available) from 19 foxes trapped in 1998 on the east end of the island was also investigated for antibodies reactive against CDV by VNT.…”

Section: Laboratory Testsmentioning

confidence: 99%

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A Suspected Canine Distemper Epidemic as the Cause of a Catastrophic Decline in Santa Catalina Island Foxes (Urocyon Littoralis Catalinae)

Timm¹,

Munson

Summers

et al. 2009

Journal of Wildlife Diseases

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ABSTRACT:The island fox (Urocyon littoralis catalinae) population on Santa Catalina Island, California, USA declined precipitously in 1999 with an approximate 95% reduction on their eastern range, an area representing 87% of the island. During this investigation, between October 1999 and April 2000, evidence of live foxes dramatically decreased. The only carcass recovered during the decline succumbed to a co-infection of canine distemper virus (CDV) and toxoplasmosis. Sequence analysis of the viral P gene, derived by polymerase chain reaction, indicated that the virus was closely related to CDV from a mainland USA raccoon (Procyon lotor). Nine of 10 foxes trapped in 1999-2000, on the eastern portion of the island after the decline, had serologic evidence of exposure to CDV, whereas only four of 19 foxes trapped in this region in 1998 had antibodies reactive against CDV. The confirmation of CDV in one deceased fox, evidence of exposure to CDV in east-end foxes in 1999-2000 compared to 1998, and documentation of raccoon introductions to the island, implicates canine distemper as the cause of the population decline.

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Pathogen exposure in endangered island fox (Urocyon littoralis) populations: Implications for conservation management

Cited by 86 publications

References 63 publications

Fatal disease and demographic Allee effect: population persistence and extinction

Fatal disease and demographic Allee effect: population persistence and extinction

Adenoviruses of canine and human origins in stool samples from free-living pampas foxes (<italic>Lycalopex gymnocercus</italic>) and crab-eating foxes (<italic>Cerdocyon thous</italic>) in São Francisco de Paula, Rio dos Sinos basin

A Suspected Canine Distemper Epidemic as the Cause of a Catastrophic Decline in Santa Catalina Island Foxes (Urocyon Littoralis Catalinae)

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