Journal: Journal of wildlife diseases
Koala (Phascolarctos cinereus) populations in the wild are in sharp decline in Australia due to deforestation, road accidents, dog attacks, and disease from infection with sexually transmitted Chlamydia spp. Severely diseased koalas that are captured are euthanized for humane reasons because antibiotics are not effective. Paradoxically, we propose that euthanizing more koalas could help to increase koala population numbers. We investigated the potential impact of systematically euthanizing diseased koalas. Using data from a well-studied koala population, and an individual-based computer simulation model, we predict that such a program would result in a larger population of koalas after 7 yr than would exist without the program. If terminally diseased and sterile koalas are euthanized and other infected captured koalas are given antibiotics, chlamydial infection could be eliminated and population growth observed after 4 yr. The practical implementation of such a program would be facilitated with further development of tools to diagnose infection and internal disease in the field.
Abstract Alopecia (hair loss) has been observed in several marine mammal species and has potential energetic consequences for sustaining a normal core body temperature, especially for Arctic marine mammals routinely exposed to harsh environmental conditions. Polar bears (Ursus maritimus) rely on a thick layer of adipose tissue and a dense pelage to ameliorate convective heat loss while moving between sea ice and open water. From 1998 to 2012, we observed an alopecia syndrome in polar bears from the southern Beaufort Sea of Alaska that presented as bilaterally asymmetrical loss of guard hairs and thinning of the undercoat around the head, neck, and shoulders, which, in severe cases, was accompanied by exudation and crusted skin lesions. Alopecia was observed in 49 (3.45%) of the bears sampled during 1,421 captures, and the apparent prevalence varied by years with peaks occurring in 1999 (16%) and 2012 (28%). The probability that a bear had alopecia was greatest for subadults and for bears captured in the Prudhoe Bay region, and alopecic individuals had a lower body condition score than unaffected individuals. The cause of the syndrome remains unknown and future work should focus on identifying the causative agent and potential effects on population vital rates.
Oslerus osleri is a filaroid parasite of the respiratory tract of canids. In North America, it is most commonly reported from coyotes (Canis latrans) and domestic dogs (Canis lupus familiaris), but reports in gray wolves (Canis lupus) are infrequent. We report a new geographic record for O. osleri in four gray wolves from Banff National Park, Alberta, Canada. Adult nematodes found in nodules in the submucosa of the trachea and bronchi were identified as O. osleri based on morphometry of spicules of males. We sequenced two segments of the genome of adult nematodes: a 1,111-base pair (bp) segment of the 18S region that was 100% identical to the 18S region of O. osleri from a coyote in California and a 537-bp segment that included the ITS-2 region and partial 5.8S and 28S genes. Histopathologically, there were submucosal nodules of adult nematodes surrounded by fibrosis and lymphoplasmacytic inflammation. These findings are consistent with O. osleri infections in other canids. The importance of this parasite in wild canid populations is unknown, but prevalence may be underestimated because many studies have focused on gastrointestinal parasites or used routine fecal flotation that has low sensitivity for this parasite. The ecology and population genetics of this parasite where multiple species of canids are sympatric warrant closer investigation to determine potential for interspecies transmission.
Abstract Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are two of the most common viruses affecting domestic cats (Felis catus). During the last two decades, reports show that both viruses also infect or affect other species of the family Felidae. Human landscape perturbation is one of the main causes of emerging diseases in wild animals, facilitating contact and transmission of pathogens between domestic and wild animals. We investigated FIV and FeLV infection in free-ranging guignas (Leopardus guigna) and sympatric domestic cats in human perturbed landscapes on Chiloé Island, Chile. Samples from 78 domestic cats and 15 guignas were collected from 2008 to 2010 and analyzed by PCR amplification and sequencing. Two guignas and two domestic cats were positive for FIV; three guignas and 26 domestic cats were positive for FeLV. The high percentage of nucleotide identity of FIV and FeLV sequences from both species suggests possible interspecies transmission of viruses, facilitated by increased contact probability through human invasion into natural habitats, fragmentation of guigna habitat, and poultry attacks by guignas. This study enhances our knowledge on the transmission of pathogens from domestic to wild animals in the global scenario of human landscape perturbation and emerging diseases.
Abstract The black-footed ferret, Mustela nigripes, is an endangered carnivore endemic to the grasslands of North America. We present the first investigation of ectoparasites associated with black-footed ferrets since reintroduction. We sampled more than 200 individuals from one of the largest and most successful reintroduced populations located in the Conata Basin of South Dakota, USA. We compared our findings with ectoparasite assemblages of sympatric carnivores and historic ferret records. We collected more than 1,000 ectoparasites consisting mainly of three flea and tick species, two of which were known historically from South Dakota. Despite our extensive sampling efforts, we did not detect any lice. This is notable because a putative host-specific louse, Neotrichodectes sp., was presumed to have gone extinct when black-footed ferrets were extirpated from the wild. The ectoparasite assemblage on black-footed ferrets comprised only generalist parasites, particularly those found on their prey such as prairie dogs (Cynomys sp.). Oropsylla hirsuta was the most abundant ectoparasite, representing 57% of all ectoparasites detected; a flea vector important in the persistence and transmission of plague. Black-footed ferrets like other endangered species undergo repeated parasite removal and vaccination efforts to facilitate population recovery, which may have unintentionally contributed to their depauperate ectoparasite community.
An incidental observation of the fly Philornis downsi parasitizing a Galapagos Flycatcher (Myiarchus magnirostris) nest has revealed new insights into the searching behavior and biology of this invasive fly parasite and its interactions with endemic land birds in the Galapagos Islands. Observations suggest that P. downsi relies on olfactory cues, or olfactory cues combined with the activity of adult birds, to locate nests and that flies continue to visit nests when chicks are >3 d old. At least 200 eggs were laid by P. downsi in different parts of the nest and >40 early-instar larvae were found inside the head of one chick, with additional larvae found in the base of the nest. Parasitism was the likely cause of mortality of both chicks found in or near the nest. This is the first published description of P. downsi parasitizing chicks of M. magnirostris and highlights the vulnerability of this endemic bird species to this invasive fly.
Worldwide, stranded marine mammals and the network personnel who respond to marine mammal mortality have provided much of the information regarding marine morbillivirus infections. An assay to determine the amount of virus present in tissue samples would be useful to assist in routine surveying of animal health and for monitoring large-scale die-off events. False negatives from poor-quality samples prevent determination of the true extent of infection, while only small amounts of tissue samples or archived RNA may be available at the time of collection for future retrospective analysis. We developed a one-step duplex real-time reverse transcriptase-quantitative-PCR assay (RT-qPCR) based on Taqman probe technology to quantify phocine distemper virus (PDV) isolated from an outbreak in harbor (Phoca vitulina concolor) and gray seals (Halichoerus grypus) along the northeast US coast in 2006. The glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) gene was selected to assess RNA quality. This duplex assay is specific for PDV and sensitive through a range of 10(0) to 10(9) copies ds-plasmid DNA. For the GAPDH target, the reaction in duplex amplified 10(0) to 10(9) copies of ds-plasmid DNA and was detectable in multiple seal species. This assay reduced the likelihood of false negative results due to degradation of tissues and well-to-well variability while providing sensitive and specific detection of PDV, which would be applicable in molecular epidemiologic studies and pathogen detection in field and laboratory investigations involving a variety of seal species.
Ranaviruses can be transmitted by contaminated water and sediment but must retain infectivity for a sufficient period to reach and infect a susceptible host. To determine the risk a virus represents once it enters the environment, its persistence in that environment must be determined. We evaluated the survival of frog virus 3 (FV3) in water and sediment from an English lake at temperatures of 4, 15, 20, and 30 C over time. The virus survived in both water and sediment; however, survival times were significantly lower in sediment. The virus lost infectivity in both matrices with a rise in temperature. In water, time required for a 90% reduction in virus titer decreased from 34 d at 4 C to 5 d at 30 C. In sediment, required time for a 90% reduction decreased from 10 d at 4 C to 1 d at 30 C. These results can be used to estimate the persistence of FV3 in the environment and indicate that the virus could remain infectious in temperate locations for extended periods during winter.
The emergence of antimicrobial resistance is arguably the most important threat to human and animal health. The impacts of antimicrobial use can reach far from the site of prescription and wildlife may serve as a conduit for the movement of resistance across landscapes, contributing to the spread of antimicrobial resistance within and between different reservoirs. We compared antimicrobial resistance and life history among wild and domestic species in Chobe, Botswana to explore key attributes and behaviors that may increase exposure and allow resistance to move between humans, animals, and ecosystems. Among 150 fecal samples evaluated from African animals, 41.3% contained Escherichia coli isolates that were resistant to one or two of 10 tested antibiotics, and 13.3% of isolates demonstrated multidrug resistance (three or more antibiotics). Resistance to each of the 10 tested antibiotics was detected among wildlife fecal samples. Resistance was widespread, but not ubiquitous, and isolates from wildlife demonstrated similar patterns of resistance to human E. coli from environmental and clinical sources in the study area. Multidrug resistance was significantly higher in carnivores, water-associated species, and species inhabiting urban areas, suggesting that life history may be key to understanding exposure patterns and transmission dynamics in heterogeneous landscapes.
Recent detection of a European-type haplotype of the cestode Echinococcus multilocularis in a newly enzootic region in British Columbia (BC) prompted efforts to determine if this haplotype was present elsewhere in wildlife in western Canada. In coyote (Canis latrans) definitive hosts in an urban region in central Saskatchewan (SK), we found a single haplotype of E. multilocularis that was most similar to a haplotype currently established in the core of this parasite’s distribution in Europe and to the European-type haplotype found in coyotes and a dog (Canis lupus familiaris) in BC. We found six haplotypes of E. multilocularis from deer mouse (Peromyscus maniculatus) intermediate hosts in southwestern SK that were closely related to, and one haplotype indistinguishable from, a haplotype previously reported in the adjacent north-central US. This is a higher level of diversity than has previously been recognized for this parasite, which suggests that the population native to central North America is well established, rather than a recent introduction from the Arctic. These findings, in combination with recent cases of alveolar hydatid cysts in dogs in Canada, raise concerns that European haplotypes of E. multilocularis may be increasing in distribution within wildlife in Canada. European haplotypes may pose greater risks to veterinary and human health than native haplotypes long established in central North America.