Serological and demographic evidence for domestic dogs as a source of canine distemper virus infection for Serengeti wildlife

Seroprevalence of canine distemper virus antibodies in free-roaming dogs in Cambodia

Canine distemper virus (CDV) can infect a wide range of mammalian carnivores and can cause severe illness and death. Domestic dogs may be an important source of this virus for endangered wild carnivores. The objective of this study was to establish the presence of CDV in rural areas of Cambodia bordering three established protected habitats, and to determine the seroprevalence of CDV in free-roaming dogs inhabiting these areas. These protected areas are home to endangered carnivores, such as Dhole (Cuon alpinus), and virus transmission from free-ranging dogs may pose a risk to endangered species. Blood samples collected from dogs were tested for CDV IgG antibodies using the Anigen rapid CDV commercial test kit (Bionote). We report the seroprevalence of CDV as 40 % of sampled free-ranging dogs. This is the first documentation of CDV in the buffer zone of important protected areas in Cambodia. The high seroprevalence rate suggests a substantial risk of disease transmission to wildlife, highlighting the need for targeted interventions. We recommend further investigation into the role of dogs in the epidemiology of CDV in Cambodian wildlife and the consideration of vaccination programs for domestic dogs in these regions.

Are Domestic Dogs (Canis familiaris) the Family Scapegoats? A Systematic Review of Canine Distemper Virus in African Wildlife, 1978-2021

Free-living wildlife across Africa is found across expansive rangelands, frequently interacting with pastoral communities, their livestock, and domestic dogs (Canis familiaris). African wildlife populations are threatened by development, poaching and disease. Infectious diseases have caused significant declines, sabotaging conservation efforts. Canine distemper virus (CDV) infections have increased in incidence in wildlife over the past four decades. Sympatric domestic dogs have been presumed to be the reservoirs of the virus for wildlife. A systematic review using Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines was carried out to investigate CDV infections in wildlife in Africa, to 1) analyze the conservation concerns associated with the disease, 2) identify the dynamics of the virus across different ecoregions, and 3) ascertain the source of the virus for free-living wildlife. The database searches identified 65 articles relevant to the study questions and an additional 43 valuable for wider discussion of the topic area. Canine distemper outbreaks were reported to occur in wildlife in six African countries, with mortality rates between 30% and 94% across all species affected. Eleven wildlife species were identified as susceptible, 64% of which (7/11) are classified as threatened by the International Union for Conservation of Nature. Disease dynamics varied between ecoregions because of differences in land use; virus strains; climate change and concurrent infections; ecotones; domestic and wildlife population densities; wildlife monitoring capacity; and wildlife movement. Nine countries reported outbreaks in domestic dog populations in or near wildlife habitats, but none reported confirmed transmission to wildlife. Of 23 reports investigating the role of domestic dogs as CDV reservoirs, 14 (61%) concluded that domestic dogs acted as either reservoirs or sources of CDV for wildlife, four (17%) did not identify dogs as reservoirs, and five (22%) were not sure of the role played by domestic dogs. This review highlights the importance of integrating active CDV surveillance in wildlife conservation programs.

Phylogenetic analysis linked fatal neurologic disease in leopards (Panthera pardus) to Asia-5 lineage of canine distemper virus in Nepal

Canine distemper virus (CDV) is responsible for a highly contagious and often fatal neurological disease that affects various carnivores, including domestic dogs. In Nepal, recent reports of CDV exposure and illness in leopards (Panthera pardus) have raised concerns about the transmission of the virus among domestic dogs and wild carnivores. To investigate the genetic lineage and spread of CDV, our study utilized archived post-mortem samples from four leopards that exhibited clinical signs suggestive of canine distemper infection. These leopards were rescued in the Palpa, Dolakha, Kathmandu, and Parbat districts. Our phylogenetic analysis revealed that the CDV strains circulating among the leopards belong to the Asia-5 lineage, which is also prevalent among dogs and wild carnivores in Nepal and neighboring India. The genetic relatedness between the leopard CDV sequences and those from both dogs and other carnivores within the Asia-5 lineage suggests that leopards in Nepal may have acquired the virus from multiple sources, potentially facilitated by their generalist dietary habits preying on dogs and even mesocarnivores. Furthermore, we inspected specific amino acid substitution in the hemagglutinin gene of leopard CDV, which also suggests possible transmission from both domestic dogs and non-canid hosts, although further research is needed to draw definitive conclusions. Given the vulnerable state of the leopard population in Nepal, already threatened by poaching and retaliatory killing, the emergence of CDV as a potential novel threat is deeply concerning. Comprehensive surveillance studies are essential to understand the dynamics of CDV spillover and to develop informed interventions. Urgent measures, including vaccination programs and effective control of the dog population, are needed to mitigate the impact of this disease and safeguard the future of Nepal's leopards and other wild carnivores.

Viruses of free-roaming and hunting dogs in Uganda show elevated prevalence, richness and abundance across a gradient of contact with wildlife

Domestic dogs (Canis lupus familiaris) live with humans, frequently contact other animals and may serve as intermediary hosts for the transmission of viruses. Free-roaming dogs, which account for over 70% of the world's domestic dog population, may pose a particularly high risk in this regard. We conducted an epidemiological study of dog viromes in three locations in Uganda, representing low, medium and high rates of contact with wildlife, ranging from dogs owned specifically for traditional hunting in a biodiversity and disease 'hotspot' to pets in an affluent suburb. We quantified rates of contact between dogs and wildlife through owner interviews and conducted canine veterinary health assessments. We then applied broad-spectrum viral metagenomics to blood plasma samples, from which we identified 46 viruses, 44 of which were previously undescribed, in three viral families, Sedoreoviridae, Parvoviridae and Anelloviridae. All 46 viruses (100 %) occurred in the high-contact population of dogs compared to 63 % and 39 % in the medium- and low-contact populations, respectively. Viral prevalence ranged from 2.1 % to 92.0 % among viruses and was highest, on average, in the high-contact population (22.3 %), followed by the medium-contact (12.3 %) and low-contact (4.8 %) populations. Viral richness (number of viruses per dog) ranged from 0 to 27 and was markedly higher, on average, in the high-contact population (10.2) than in the medium-contact (5.7) or low-contact (2.3) populations. Viral richness was strongly positively correlated with the number of times per year that a dog was fed wildlife and negatively correlated with the body condition score, body temperature and packed cell volume. Viral abundance (cumulative normalized metagenomic read density) varied 124-fold among dogs and was, on average, 4.1-fold higher and 2.4-fold higher in the high-contact population of dogs than in the low-contact or medium-contact populations, respectively. Viral abundance was also strongly positively correlated with the number of times per year that a dog was fed wildlife, negatively correlated with packed cell volume and positively correlated with white blood cell count. These trends were driven by nine viruses in the family Anelloviridae, genus Thetatorquevirus, and by one novel virus in the family Sedoreoviridae, genus Orbivirus. The genus Orbivirus contains zoonotic viruses and viruses that dogs can acquire through ingestion of infected meat. Overall, our findings show that viral prevalence, richness and abundance increased across a gradient of contact between dogs and wildlife and that the health status of the dog modified viral infection. Other ecological, geographic and social factors may also have contributed to these trends. Our finding of a novel orbivirus in dogs with high wildlife contact supports the idea that free-roaming dogs may serve as intermediary hosts for viruses of medical importance to humans and other animals.

Study of Canine Distemper Virus Presence in Catalonia's Wild Carnivores through H Gene Amplification and Sequencing

Canine distemper virus (CDV) is recognised worldwide as an important pathogen in both domestic and wild carnivores. Few data are available on its impact and spread on the wildlife/wildlife-domestic animal-environment interface. This study, aimed at developing a conservation-oriented control strategy, analysed 89 sick or deceased animals from 2019 to 2023 at the Wildlife Rehabilitation Centre in Torreferrussa. RT-PCR and sequencing of the partial H gene were used to detect and analyse CDV in tissues. The total positive percentage was 20.22% (18/89), comprising 13 red foxes (44.8%), 4 European badgers (28.6%), and 1 American mink (4.5%), while 24 Eurasian otters tested negative. Phylogenetic analysis indicated that all of the CDV strains belong to the European lineage. Geographically distant individuals and different species shared the same viral strain, suggesting a strong capacity of CDV for interspecies and long-distance transmission. This calls for further research, particularly focusing on potential impacts of CDV on endangered carnivores.

INTESTINAL PARASITES IN PECARI TAJACU AND SUS SCROFA DOMESTICUS IN THE CAATINGA FROM SOUTHEASTERN PIAUÍ, BRAZIL

This study identifies gastrointestinal parasites in the feces of Pecari tajacu (caititu) and Sus scrofa domesticus (domestic pig) in southeastern Piauí, Brazil. The region covers 2 protected areas, Serra da Capivara National Park and Serra das Confusões National Park, and surrounding communities. Fecal samples from 64 animals, 42 from domestic swine and 22 from caititu, collected between 1985 and 2013, were analyzed by optical microscopy. Helminths and/or protozoa were found in 64% of the domestic pig samples and 27% of the caititu samples, totaling 18 morphospecies: Nematoda, Spirurida (2 morphospecies), Trichostrongyloidea, Eimeriidae, Aspidodera sp., Bertiella sp., Metastrongylus sp., Trichostrongylus sp., Moniezia sp., Gongylonema sp., Trichuris suis, Spirocerca lupi, Macracanthorhyncus hirudinaceus, Globocephalus urosubulatus, Strongyloides cf ransomi, Balantioides coli, and Eimeria cf scabra. The highest parasite diversity was obtained in the pig samples, totaling 15 morphospecies, compared to only 6 in caititus, with S. cf ransomi, G. urosubulatus, and S. lupi present in both hosts. We discuss the presence of parasites associated with domestic animals around the Protected Areas and potentially zoonotic parasites close to human communities, which raise concerns about the conservation of wildlife, human health, and livestock in the region.

Phylogenetic characterization of canine distemper virus from stray dogs in Kathmandu Valley

Canine distemper is a highly contagious, often fatal disease caused by canine distemper virus (CDV) in domestic dogs and wild carnivores. The virus has caused mass epidemics in both wild and captive carnivores of high conservation value such as tigers, lions and leopards. Hence, understanding and managing CDV outbreaks is particularly important in Nepal, which is home to many species of threatened wild carnivores including tigers, leopards, snow leopards, dholes and wolves, and also contains a large population of stray dogs. Previous studies have suggested that CDV may pose a threat to wild carnivores, but there have not been any studies characterizing the genetic strains of the virus circulating in Nepal's carnivores. We collected invasive and non-invasive biological samples from stray dogs in Kathmandu Valley and genetically characterized the strains of CDV in the dogs to belong to the Asia-5 lineage by using phylogenetic analysis. The same lineage also contained CDV strains sequenced from dogs, civets, red panda and lions in India. Based on our phylogenetic analysis, we think it is likely that CDV is maintained through sylvatic cycle among sympatric carnivores allowing the recurring spillovers and outbreaks. It is crucial to prevent the virus transmission from reservoir hosts to other species, especially threatened populations of large carnivores in Nepal. Hence, we recommend for regular surveillance of CDV targeting wild carnivores in addition to the domestic dogs.

Effects of a novel recombinant Gonadotropin-Releasing Hormone-1 vaccine on the reproductive function of mixed-breed dogs (Canis familiaris) in Taiwan

Immunocastration is an effective alternative to surgical castration for controlling the population of animals. As gonadotropin-releasing hormone (GnRH) regulates the reproductive endocrine system in mammals, it is a target antigen for vaccine formulation. Through this study, we evaluated the effectiveness of a recombinant subunit GnRH-1 vaccine for the immunocastration of the reproductive function of 16 mixed-breed dogs (Canis familiaris) provided voluntarily by different households. All the dogs were deemed clinically healthy prior to and during the experiment. A specific anti-GnRH immune response was detected at Week 4, which was maintained for at least 24 weeks after vaccination. Moreover, decreased levels of sexual hormones (testosterone as well as progesterone and estrogen, respectively) were observed in both male and female dogs. Estrous suppression was apparent in female dogs, and testicular atrophy and poor semen quality (concentration, abnormality, and viability) were observed in male dogs. In conclusion, the recombinant subunit GnRH-1 vaccine could successfully suppress fertility and delay the estrous cycle in canines. These results support the efficacy of the recombinant subunit GnRH-1 vaccine; thus, it is a suitable candidate for fertility control in dogs.

Epidemiologic Factors Supporting Triage of Infected Dog Patients Admitted to a Veterinary Hospital Biological Isolation and Containment Unit

The teaching hospital of the Faculty of Veterinary Medicine at the University of Lisbon hosts a Biological Isolation and Containment Unit (BICU) for the hospitalization of both confirmed and suspected animals of an infectious disease. This study targets the BICU dog population to identify and characterize the most frequent infectious diseases recorded in a 7-year period. Several epidemiologic factors were analyzed for their significance to triage infected cases. During the study period, 534 dogs were admitted, of which 263 (49.3%) had a confirmed infectious disease diagnosis: parvovirosis (49.4%; n = 130); leptospirosis (21.7%; n = 57); multidrug-resistant (MDR) bacterial infection; (10.6%; n = 28), and canine distemper (9.9%; n = 26). Several potential risk factors for these diseases were identified: age under 2 years old (p < 0.001), incomplete vaccination for parvovirosis (p < 0.001), age ≥ 10 years old (p < 0.001), and the presence of concomitant disorders for MDR-infected cases (p = 0.03). Logistic regression models were constructed to classify cases and controls. The sensitivity and specificity estimates were very high (>0.83) for parvovirosis, MDR, and distemper infections. A lower sensitivity (0.77) was obtained for identifying cases with leptospirosis. In conclusion, infectious diseases are frequent, hence, it is essential to decrease their occurrence through effective preventive measures such as vaccination. The constructed logistic models can also help in triaging admitted dogs with a potential infectious disease.

Seroprevalence of canine distemper virus (CDV) in the free-roaming dog (Canis familiaris) population surrounding Chitwan National Park, Nepal

Canine distemper virus (CDV) is a global multi-host pathogen that is capable of causing considerable mortality in a range of species and is important in the field of conservation medicine. Nepal's Chitwan National Park is a protected area providing habitat for 32% of the country's mammal species including endangered carnivores such as the Bengal tiger (Panthera tigris tigris) that are susceptible to CDV. The presence of free-roaming dogs around protected areas could represent a source of infectious disease for transmission to local wildlife. A cross-sectional demographic and canine distemper virus seroprevalence study of 100 free-roaming dogs from the Chitwan National Park buffer zone and surrounding area was conducted in November 2019. The overall seroprevalence indicating past exposure to canine distemper virus was 80.0% (95% CI: 70.8-87.3). Of the host variables assessed, sex and age were positively associated with seroprevalence at the univariable level, with male dogs demonstrating lower seroprevalence than females (OR = 0.32, 95% CI: 0.11-0.91) and adult dogs demonstrating higher seroprevalence than juveniles (OR = 13.94, 95% CI: 1.37-142.29). The effect of sex was no longer significant at the multivariable level, but the direction of the effect remained the same. The effect of age remained significant after multivariable analysis (OR = 9.00, 95% CI: 1.03-192.75). No spatial associations were demonstrated in relation to the buffer zone area or boundary of Chitwan National Park. Free-roaming dog neutering and vaccination programmes can provide a useful baseline for future CDV studies in the region, and a proxy to monitor disease threats to susceptible wildlife.

Persistent and Severe Viral Replication in PBMCs with Moderate Immunosuppression Served an Alternative Novel Pathogenic Mechanism for Canine Morbillivirus

Measles virus and canine distemper virus (CDV) cause lethal infections in their respective hosts characterized by severe immunosuppression. To furtherly acknowledge the attenuated mechanisms of the regionally ongoing epidemic CDV isolates and provide novel perspectives for designing new vaccines and therapeutic drugs, a recombinant CDV rHBF-vacH was employed with a vaccine hemagglutinin (H) gene replacement by reverse genetics based on an infectious cDNA clone for the CDV wild-type HBF-1 strain. Interestingly, unlike previously published reports that a vaccine H protein completely changed a pathogenic wild-type CDV variant to be avirulent, rHBF-vacH was only partially attenuated by alleviating the degree of viral immunosuppression, and still caused 66.7% lethality in ferrets with a prolonged period of disease. Further comparisons of pathogenic mechanisms proved that the weaker but necessary invasions into peripheral blood mononuclear cells (PBMCs) of rHBF-vacH, and subsequently persistent viral replications in PBMCs and multiple organs, together contributed to its 66.7% mortality. In addition, despite significantly higher titers than the parent viruses, rHBF-vacH would not be a suitable candidate for a live vaccine, with great invasion and infection potentials of PBMCs from 16 tested kinds of host species. Altogether, sustained and severe viral replication in PBMCs with moderate immunosuppression was first proven to be an alternative novel pathogenic mechanism for CDV, which might help us to understand possible reasons for CDV fatal infections among domestic dogs and the highly susceptible wild species during natural transmission. IMPORTANCE Despite widespread vaccine campaigns for domestic dogs, CDV remained an important infectious disease in vaccinated carnivores and wild species. In recent years, the regionally ongoing epidemic CDV isolates have emphasized conservation threats to, and potentially disastrous epidemics in, endangered species worldwide. However, little is known about how to deal with the CDV variants constantly regional epidemic. In this study, we employed a recombinant CDV rHBF-vacH with a vaccine H gene replacement in a CDV wild-type HBF-1 context to attenuate the epidemic CDV variant to design a new vaccine candidate. Interestingly, rHBF-vacH was only partially attenuated by alleviating the degree of viral immunosuppression, and still caused 66.7% lethality in ferrets by weaker but necessary invasions into PBMCs, and subsequently persistent and severe viral replications in PBMCs. Significantly higher virus titers of rHBF-vacH in vitro might indicate the rapid cell-to-cell spreads in vivo that indirectly contribute to fatal infections of rHBF-vacH in ferrets.

Canine Distemper Virus in Endangered Species: Species Jump, Clinical Variations, and Vaccination

Canine morbillivirus (Canine distemper virus, CDV) is the cause of distemper in a large number of different species, some of which are endangered. The clinical outcome associated with infection is variable and based on many factors, including the host species, the immune response of the individual animal to the infection, and variation in virus tropism and virulence. Unfortunately, the viral characteristics associated with virulence versus attenuation are not fully characterized, nor are the specific mutations that allow this virus to easily move and adapt from one species to another. Due to its wide host range, this virus is difficult to manage in ecosystems that are home to endangered species. Vaccination of the domestic dog, historically considered the reservoir species for this virus, at dog-wildlife interfaces has failed to control virus spread. CDV appears to be maintained by a metareservoir rather than a single species, requiring the need to vaccinate the wildlife species at risk. This is controversial, and there is a lack of a safe, effective vaccine for nondomestic species. This review focuses on topics that are paramount to protecting endangered species from a stochastic event, such as a CDV outbreak, that could lead to extinction.

Investigating the free-roaming dog population and gastrointestinal parasite diversity in Tulúm, México

Free-roaming domestic dogs (Canis lupus familiaris) pose major conservation and public health risks worldwide. To better understand the threat of domestic dogs to wildlife and people and add to the growing literature on free-roaming dog ecology, a study was conducted to estimate the dog population in Tulúm, México. A modified mark-recapture technique and program MARK were used to obtain dog population estimates along six different transects dividing the city. Population estimates ranged from 19.75 dogs in one transect to 101.841 dogs in another, with 150 total dogs identified throughout the study and an estimated minimum population density of 48.57 dogs/km2. Fecal samples were also opportunistically collected for parasite identification through fecal flotation analysis using the McMaster technique. Out of 25 samples collected, 19 tested positive for gastrointestinal parasites with the most common species found being Ancylostoma caninum, followed by Toxocara canis, Dipylidium caninum, and Cystoisospora spp. Parasite loads ranged from 50 to 10,700 ova per gram of feces. The large population of free-roaming dogs and the prevalence of three zoonotic parasites highlight the importance of understanding free-roaming dog ecology and educating the public on the health risks free-roaming dogs pose. Los perros callejeros (Canis lupus familiaris) representan un gran riesgo para la conservación de animales y la salud pública mundialmente. Para comprender mejor la amenaza que significan los perros domésticos para la fauna silvestre y los humanos y aportar a la creciente bibliografía sobre la ecología de los perros callejeros, se realizó una investigación para estimar la población de los perros en Tulúm, México. Se utilizó una técnica modificada de marcado y recaptura junto con el programa MARK para estimar la población canina en seis transectos de la ciudad. Los estimados varían desde 19.75 perros en un transecto hasta 101,841 en otro, con un total de 150 perros identificados en el transcurso de la investigación y una densidad mínima estimada de 48,57 perros/km2. Además, se hizo una recolección oportunista de muestras de heces para la identificación de parásitos por medio del análisis de flotacíon fecal, con el método McMaster. De las 25 muestras recolectadas, 19 resultaron positivas para parásitos gastrointestinales, de las cuales las especies más comunes fueron Ancylostomoa caninum, seguida por Toxocara canis, Dipylidium caninum, y Cystoisospora spp. Las cargas parasitarias variaron desde 50 hasta 10.700 óvulos por gramo de heces. La alta población de perros callejeros y la prevalencia de tres enfermedades zoonóticas resaltan la importancia de entender la ecología de los perros callejeros y educar al público sobre los riesgos que significan los perros callejeros para la salud.

A mixed-methods approach to understanding domestic dog health and disease transmission risk in an indigenous reserve in Guyana, South America

Domestic dogs (Canis lupus familiaris) can transmit a variety of pathogens due to their ubiquitousness in urban, rural and natural environments, and their close interactions with wildlife and humans. In this study, we used a mixed-methods approach to assess the role of domestic dogs as potential intermediaries of disease transmission from wildlife to humans among indigenous Waiwai in the Konashen Community Owned Conservation Area, Guyana. To address these objectives we 1) performed physical examinations and collected biological samples to assess Waiwai domestic dog health, and 2) administered questionnaires to characterize the role of dogs in the community and identify potential transmission pathways between wildlife, dogs, and humans. We observed ectoparasites on all dogs (n = 20), including: fleas (100%), ticks (15%), botflies (30%), and jigger flea lesions (Tunga penetrans) (80%). Ten percent of dogs were seropositive for Ehrlichia canis/ewingii, 10% were positive for Dirofilaria immitis, and one dog was seropositive for Leishmania infantum. All dogs (n = 20) were seronegative for: canine distemper virus, Brucella canis, Leptospira serovars, Trypanosoma cruzi, Anaplasma phagocytophilum/platys and Borrelia burgdorferi. Our questionnaire data revealed that the Waiwai remove ectoparasites from their dogs, clean up dog feces, and administer traditional and/or Western medicine to their dogs. White blood cell, strongyle-type ova, and eosinophil counts were lower in dogs that were not frequently used for hunting, dogs that did receive traditional and/or western medicine, and dogs that were frequently kept in elevated dog houses, although differences were not statistically significant. While our results suggest that the Waiwai have developed cultural practices that may promote dog health and/or prevent zoonotic disease transmission, more research is necessary to determine the efficacy of these practices. Our study provides important data on the health of dogs and the potential for disease transmission to humans in a zoonotic hotspot.

Domestic dogs are found throughout the world and interact closely with both wildlife and humans. Dogs can harbor numerous diseases that can be transmitted to other domestic and wildlife species, and human populations. They can serve as bridges, moving diseases between unconnected populations. Additionally, dogs can help in the early detection of wildlife and human diseases. Therefore, understanding what pathogens domestic dogs harbor can inform both wildlife and human health. In this study, we performed physical examinations, collected biological samples, and administered questionnaires to assess dog health and understand the role of dogs as potential bridges of disease transmission from wildlife to humans among indigenous Waiwai in the Konashen Community Owned Conservation Area, Guyana. On physical exam, we observed ectoparasites on all dogs, however, few pathogens were detected with diagnostic screening. Our questionnaire data revealed that the Waiwai engage in husbandry practices that may promote Waiwai dog health.

Serosurvey of viral pathogens in free-ranging dog populations in the high altitude Trans-Himalayan region

Dogs, as reservoir hosts, have been implicated in the decline of carnivore populations across the globe. We conducted a serosurvey of free-ranging dog populations to assess the population level exposure rates to three viral pathogens, canine parvovirus (CPV), canine distemper virus (CDV) and canine adenovirus (CAV) in a Trans-Himalayan landscape in India that is home to the endangered Snow Leopard. A total of 97 dogs were sampled across six villages as a part of a surgical sterilization campaign during the study period. Samples were tested for IgG antibodies using a table top ELISA kit. Exposure rates to the three viral pathogens in the dog populations was high; 100% for CPV, 54% for CDV and 66% for CAV, with high positive immunoglobulin titer values for CAV and CPV, and low to moderate values for CDV. Overall conservation efforts for native carnivores need to address the role of free-ranging domestic dogs in disease transmission.

Attitudes towards free-roaming dogs and dog ownership practices in Bulgaria, Italy, and Ukraine

Free-roaming dog population management is conducted to mitigate risks to public health, livestock losses, wildlife conservation, and dog health and welfare. This study aimed to determine attitudes towards free-roaming dogs and their management and describe dog ownership practices in three European countries. We distributed an online questionnaire comprising questions relating to dog ownership practices and attitudes towards free-roaming dogs using social media. We used logistic regression and ordinal probit models to determine associations between demographic and other factors with ownership practices and attitudes towards free-roaming dogs. This study found that most surveyed respondents wanted to see a reduction in free-roaming dog numbers, and felt that this should be achieved through sheltering, catch-neuter-release, and by controlling owned dog breeding. We identified significant associations between both attitudes and ownership practices with gender, religious beliefs, age, education level, reason for dog ownership, previous experience with free-roaming dogs, and country of residence. Respondents who identified as: (i) male, (ii) holding religious beliefs, (iii) owning dogs for practical reasons, (iv) being young, or (v) having no schooling or primary education had a lower probability of neutering and a higher probability of allowing dogs to roam. Respondents who identified as: (i) female, (ii) feeling threatened by free-roaming dogs, (iii) older, or (iv) having more education had a higher probability of answering that increases in free-roaming dog numbers should be prevented. These findings can help to inform future dog population management interventions in these countries. We emphasise the importance of considering local attitudes and dog ownership practices in the development of effective dog population management approaches.

Molecular and pathological screening of canine distemper virus in Asiatic lions, tigers, leopards, snow leopards, clouded leopards, leopard cats, jungle cats, civet cats, fishing cat, and jaguar of different states, India

The present investigation was conducted to rule out canine distemper (CD) diseases in Indian wild felids (Asiatic lions, tigers, leopards, snow leopards, clouded leopards, leopard cats, jungle cats, civet cats, fishing cat, and jaguar). The collected samples were screened for CD virus (CDV) by histopathology (HP), immunohistochemistry (IHC) and reverse transcriptase-polymerase chain reaction (RT-PCR) targeting H gene and N gene. The HP and IHC of suspected samples portrayed that 22 [11 leopards, 6 lions, 3 tigers, 1 snow leopard and 1 civet cat] out of 129 (17.05%) wild felids were positive for CD. The major pathological consequences were observed in spleen, lung, kidney and brain. The syncytia and intranuclear as well as intracytoplasmic eosinophilic inclusion bodies were seen in CDV infected cells. Although the histopathological lesions in spleen were more specific and consistent, however, the severe demyelinated leukoencephalitis (usually expected in CD infected dog) was not observed in the brain of any Indian wild felids. Conversely, the CDV antigen has been portrayed via IHC in pancreatic islets of Langerhans of tiger species for the first time in this study. Moreover, the concurrent CD and babesiosis has also been observed in a lioness without a usual coffee-coloured urine. The N gene and H gene of CDV isolates were amplified, sequenced and subsequently constructed the phylogenetic tree. The phylogenetic analysis of H gene revealed that the CDV isolates from Indian lion formed separate clade with CDV isolates from Indian dog and Indian palm civet cat. Furthermore, two CDV isolates from Indian tigers formed clade with Onderstepoort vaccine strain and CDV isolates from dogs of Uttar Pradesh, USA and UK. Evidently, CDV is circulating in Indian wild felids and causing diseases in them.

Drivers of canine distemper virus exposure in dogs at a wildlife interface in Janos, Mexico

BACKGROUND

Human population expansion has increased the contact between domestic animals and wildlife, thereby increasing the transmission of infectious diseases including canine distemper virus (CDV). Here, we investigated the risk factors associated with CDV exposure in domestic and wild carnivores from the Janos Biosphere Reserve (JBR), Mexico.

METHODS

A cross-sectional household questionnaire study was performed in four rural towns to investigate the risk factors associated with the presence of CDV in domestic and wild carnivores from the JBR, Mexico. In addition, we tested serum samples from 70 dogs and three wild carnivores, including one bobcat (Lynx rufus), one striped skunk (Mephitis mephitis) and one gray fox (Urocyon cinereoargenteus) for CDV antibodies using immunochromatographic and viral neutralization assays.

RESULTS

Overall, 62% of domestic dogs were seropositive for CDV, and the presence of antibodies was significantly higher in free-roaming owned dogs than dogs with restricted movement. Among the wild carnivores, only the bobcat was seropositive. The rate of vaccination against CDV in dogs was low (7%), and there was a high rate of direct interactions between domestic dogs and wild carnivores.

CONCLUSION

Our serological assays show that CDV is circulating in both domestic dogs and wild carnivores, suggesting cross-species transmission. Our finding of low vaccination rates, high number of unrestrained owned dogs and direct interactions between wildlife and domestic animals reported in the region may be perpetuating the high prevalence of the virus and increasing the risk of CDV transmission between wild and domestic carnivores. Therefore, long-term longitudinal studies are recommended in order to monitor infectious diseases at the domestic-wildlife interface in this highly biodiverse region.

A survey of intestinal helminths in domestic dogs in a human-animal-environmental interface: the Oloisukut Conservancy, Narok County, Kenya

Dogs living in a domestic-wildlife interface can serve as reservoirs and sentinels of parasites shared among humans, domestic animals and wildlife. In Kenya, the epidemiology of intestinal parasites of dogs and their role as reservoirs of zoonoses is poorly understood, especially in domestic-wildlife interfaces. This study aimed to determine the occurrence of intestinal helminths in domestic dogs in the Oloisukut Conservancy. One hundred dog faecal samples were collected per rectum and examined microscopically following zinc chloride flotation and formal-ether concentration techniques. Genotyping of helminths was achieved by nested polymerase chain reaction of NADH dehydrogenase subunit 1, cytochrome oxidase 1 and partial sequencing. Nine genera were detected by microscopy in 65 (65%) dog faecal samples from 54/76 (71.05%) households. The most frequent helminths were hookworm (39%), Spirometra spp. (17%), taeniids (13%), Toxocara spp. (10%), Trichuris spp. (10%), Spirocerca lupi (5%), Physaloptera spp. (2%), Dipylidium caninum (1%) and Strongyloides spp. (1%). Ancylostoma caninum was the only hookworm species detected in dogs, while Taenia serialis and Taenia madoquae were detected in four and one faecal samples, respectively. This study reports for the first time the molecular detection of the cestodes Spirometra theileri, D. caninum and Mesocestoides sp. in dogs in Kenya. The presence of zoonotic helminths in dogs indicates that the residents of this conservancy are exposed to public health risks. The helminths reported here confirm the interaction of domestic dogs with wildlife. An integrated control programme involving the medical, veterinary and wildlife conservation professionals is needed to avert transmission of infectious diseases to humans, domestic animals and wildlife.

Abandonment of dogs in Latin America: Strategies and ideas

In this article, we gathered information from postgraduate theses and scientific articles published in several databases using inclusion criteria that had been made in Latin America, in countries with similar economic conditions, and also in the USA to present a point of comparison. The objective of this review is to broaden the readers' understanding of the causes of the increasing numbers of stray dogs and the reasons why people abandon pets in the streets, specifically in Latin America. It also discusses adoption and responsible ownership, identifies what failed in promoting positive human-dog interaction, and suggests strategies to address this problem. It concludes that adoption alone is not an effective solution but that it is necessary to offer education and awareness programs for owners, organize sterilization campaigns, and develop and apply - with the corresponding authorities - measures to ensure animal welfare that will provide benefits for society and improve animal quality of life. The role of veterinarians is fundamental in education and in disseminating the necessary information to orient people before they acquire a pet and prevent animal abandonment to resolve this problem.

Beware of dogs! Domestic animals as a threat for wildlife conservation in Alpine protected areas

Diseases are natural regulating factors of wildlife populations, but some pathogens may become an important threat in wildlife conservation, especially for endangered species. The presence of domestic animals may foster the spread of diseases in natural population, although their role in the dynamic of infections in wildlife is not clear. In this study, we investigated the presence and prevalence of a range of multi-host pathogens in wild species (red fox, Eurasian badger, beech marten, pine marten, stoat for a total of 89 carcasses analysed) and domestic animals (n = 52 shepherd and n = 25 companion dogs) living in a protected area of the Alps (the Gran Paradiso National Park) and discussed the role of domestic dogs as possible source of infection for wild species. Our results showed that domestic dogs are potential shedder of three important pathogens: Canine distemper virus, Toxoplasma sp. and Neospora caninum. In particular, shepherd dogs seem to represent a threat for wildlife as they are exposed to multiple pathogens because of free-roaming, scavenging lifestyles and close proximity to livestock. However, also companion dogs more subject to veterinary care may foster the spread of pathogens. Our results highlight the importance of regulating the access of domestic dogs to protected areas that aim at preserving biodiversity and enhancing the conservation of endangered species.

Molecular Characteristics of Carnivore protoparvovirus 1 with High Sequence Similarity between Wild and Domestic Carnivores in Taiwan

Carnivore protoparvovirus 1 (CPPV-1) is a DNA virus causing gastrointestinal disease and immunosuppression in various terrestrial carnivores. Domestic dogs and cats are considered the primary CPPV-1 reservoirs. The habitat overlap of wild carnivores and free-roaming dogs increases the threat of CPPV-1 transmission between them. This study explored the CPPV-1 distribution among wild carnivores in Taiwan through PCR screening and compared the partial capsid protein (VP2) gene sequences from wild and domestic carnivores. In total, 181 samples were collected from 32 masked palm civets (Paguma larvata), 63 Chinese ferret badgers (Melogale moschata), and 86 crab-eating mongooses (Herpestes urva), from 2015 to 2019 were screened for CPPV-1. The average prevalence of CPPV-1 was 17.7% (32/181), with the highest prevalence in masked palm civets (37.5%). In addition, a masked palm civet was coinfected with two CPPV-1 strains. Among the 33 partial VP2 gene sequences, 23 were identical to the sequences amplified from domestic dogs and cats in Asia, and the remaining 10 were identified for the first time. This study supported the circulation of CPPV-1 strains with the same genomic features as domestic carnivores that are also in wild carnivores from the same environment in Taiwan by molecular data. Therefore, further population control and health management of free-roaming domestic carnivores are recommended.

Demographic and Pathogens of Domestic, Free-Roaming Pets and the Implications for Wild Carnivores and Human Health in the San Luis Region of Costa Rica

Habitat loss and degradation, restricted ranges, prey exploitation, and poaching are important factors for the decline of several wild carnivore populations and additional stress from infectious agents is an increasing concern. Given the rapid growth of human populations in some regions like Costa Rica, pathogens introduced, sustained, and transmitted by domestic carnivores may be particularly important. To better understand the significance of domestic carnivore pathogens for wildlife, we determine the prevalence of infection and possible mechanisms for contact between the two groups. The demographics, role in the household, and pathogens of pet dogs and cats was studied during three annual spay/neuter clinics in San Luis, Costa Rica. Most dogs were owned primarily as pets and guard animals, but ~10% were used for hunting. Cats were owned primarily as pets and for pest control. Both roamed freely outdoors. We detected high prevalences of some pathogens (e.g., carnivore protoparvovirus 1 and Toxoplasma gondii). Some pathogens are known to persist in the environment, which increases the probability of exposure to wild carnivores. This study demonstrated that domestic pets in San Luis, home to a number of protected and endangered wildlife species, are infected with pathogens to which these wild species are potentially susceptible. Additionally, results from our questionnaire support the potential for domestic and wild animal contact, which may result in disease spillover.

Cross-species transmission of retroviruses among domestic and wild felids in human-occupied landscapes in Chile

Human transformation of natural habitats facilitates pathogen transmission between domestic and wild species. The guigna (Leopardus guigna), a small felid found in Chile, has experienced habitat loss and an increased probability of contact with domestic cats. Here, we describe the interspecific transmission of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) between domestic cats and guignas and assess its correlation with human landscape perturbation. Blood and tissue samples from 102 free-ranging guignas and 262 domestic cats were collected and analyzed by PCR and sequencing. Guigna and domestic cat FeLV and FIV prevalence were very similar. Phylogenetic analysis showed guigna FeLV and FIV sequences are positioned within worldwide domestic cat virus clades with high nucleotide similarity. Guigna FeLV infection was significantly associated with fragmented landscapes with resident domestic cats. There was little evidence of clinical signs of disease in guignas. Our results contribute to the understanding of the implications of landscape perturbation and emerging diseases.

Domestic Dogs and Wild Foxes Interactions in a Wildlife-Domestic Interface of North-Central Chile: Implications for Multi-Host Pathogen Transmission

Domestic dogs (Canis familiaris) often cohabite at interfaces shared by humans and wildlife, interacting with wild canids as predators, prey, competitors and reservoirs of several multi-host pathogens, such as canid-borne micro and macro parasites that could impact on wildlife, livestock and public health. However, spatio-temporal patterns of indirect interactions as promoters of pathogen transfer between domestic and wild canids are largely unknown. In this study, we used camera traps to describe the activity patterns and habitat use of dogs, chilla (Lycalopex griseus) and culpeo (Lycalopex culpaeus) foxes and identify the local-scale factors that may affect the frequency of dog-fox interactions through an anthropization gradient of the Coquimbo region, Chile. We assessed local-scale variables that may predict the number of interactions between dogs and foxes, and compared the time interval between dog-culpeo and dog-chilla interactions. Our findings suggested that closeness to urbanized zones predicts the frequency of indirect interactions between dogs and foxes. We found higher number of dog-fox interactions (60 interactions) at a periurban site adjacent to two coastal towns (Tongoy and Guanaqueros), compared to other two more undisturbed sites (12 interactions) increasingly distanced from urbanized areas. We showed that dogs interacted more frequently with chilla foxes (57 interactions) than with culpeo foxes (15 interactions), and the first interaction type occurred almost exclusively at the periurban site, where dogs and chillas were more frequently detected than in the other sites. We detected a marked temporal segregation between dogs and foxes, but dog-chilla interactions resulted in shorter time intervals (2.5 median days) compared to dog-culpeo interactions (7.6 median days), suggesting a higher potential risk of pathogen spillover between the first species pairing. Based on previous studies, we suggest periurban zones may constitute a potential focus of pathogen exposure between dog and fox populations in the study area. Our research contributes to improving the knowledge on the spatio-temporal patterns of interspecific contact between invasive and native carnivores within the context of multi-host pathogen dynamics. Our outcomes will inform theoretical epidemiological models designed to predict and minimize the contact risk between domestic and threatened species, guiding effective control strategies at the wildlife-domestic interface.

Distemper, extinction, and vaccination of the Amur tiger

Canine distemper virus (CDV) has recently emerged as an extinction threat for the endangered Amur tiger (Panthera tigris altaica). CDV is vaccine-preventable, and control strategies could require vaccination of domestic dogs and/or wildlife populations. However, vaccination of endangered wildlife remains controversial, which has led to a focus on interventions in domestic dogs, often assumed to be the source of infection. Effective decision making requires an understanding of the true reservoir dynamics, which poses substantial challenges in remote areas with diverse host communities. We carried out serological, demographic, and phylogenetic studies of dog and wildlife populations in the Russian Far East to show that a number of wildlife species are more important than dogs, both in maintaining CDV and as sources of infection for tigers. Critically, therefore, because CDV circulates among multiple wildlife sources, dog vaccination alone would not be effective at protecting tigers. We show, however, that low-coverage vaccination of tigers themselves is feasible and would produce substantive reductions in extinction risks. Vaccination of endangered wildlife provides a valuable component of conservation strategies for endangered species.

Virome of crab-eating (Cerdocyon thous) and pampas foxes (Lycalopex gymnocercus) from southern Brazil and Uruguay

Crab-eating (Cerdocyon thous) and Pampas foxes (Lycalopex gymnocercus) are wild canids distributed in South America. Domestic dogs (Canis lupus familiaris) and wild canids may share viral pathogens, including rabies virus (RABV), canine distemper virus (CDV), and canine parvovirus 2 (CPV-2). To characterize the virome of these wild canid species, the present work evaluated the spleen and mesenteric lymph node virome of 17 crab-eating and five Pampas foxes using high-throughput sequencing (HTS). Organ samples were pooled and sequenced using an Illumina MiSeq platform. Additional PCR analyses were performed to identify the frequencies and host origin for each virus detected by HTS. Sequences more closely related to the Paramyxoviridae, Parvoviridae and Anelloviridae families were detected, as well as circular Rep-encoding single-stranded (CRESS) DNA viruses. CDV was found only in crab-eating foxes, whereas CPV-2 was found in both canid species; both viruses were closely related to sequences reported in domestic dogs from southern Brazil. Moreover, the present work reported the detection of canine bocavirus (CBoV) strains that were genetically divergent from CBoV-1 and 2 lineages. Finally, we also characterized CRESS DNA viruses and anelloviruses with marked diversity. The results of this study contribute to the body of knowledge regarding wild canid viruses that can potentially be shared with domestic canids or other species.

Harnessing genomics to trace the path of a viral outbreak in African lions

Predicting the emergence of novel infectious diseases requires an understanding of how pathogens infect and efficiently spread in alternative naïve hosts. A pathogen's ability to adapt to a new host (i.e. host shift) oftentimes is constrained by host phylogeny, due to limits in the molecular mechanisms available to overcome host-specific immune defences (Longdon et al., 2014). Some pathogens, such as RNA viruses, however, have a propensity to jump hosts due to rapid mutation rates. For example, canine distemper virus (CDV) infects a broad range of terrestrial carnivores, as well as noncarnivore species worldwide, with a host range that is distributed across 5 orders and 22 families (Beineke et al., 2015). In 1993-1994, a severe CDV outbreak infected multiple carnivore host species in Serengeti National Park, causing widespread mortality and the subsequent decline of the African lion (Panthera leo) population (Roelke-Parker et al., 1996). While previous studies established domestic dogs (Canis lupus familiaris) as the disease reservoir, the precise route of transmission to lions remained a mystery, and a number of wild carnivore species could have facilitated viral evolution and spread. In this issue of Molecular Ecology, Weckworth et al. (2020) used whole-genome viral sequences obtained from four carnivore species during the CDV outbreak, in combination with epidemiological data, to illuminate the pathway and evolutionary mechanisms leading to disease emergence in Serengeti lions.

Why Let the Dogs Out? Exploring Variables Associated with Dog Confinement and General Characteristics of the Free-ranging Owned-Dog Population in a Peri-urban Area

Free-ranging dogs (FRDs), are a problem in several countries, with impacts on humans, domestic animals, and wildlife, although increasing evidence suggests that most FRDs are owned. Therefore, understanding dog ownership on a fine scale is critical. The main objectives of this study were to explore dog management in rural localities from central Chile focusing on modeling owner-related variables associated with dog confinement and characterize confined and FRDs populations. Interviews (170) were carried out in Paine municipality, reporting a human:dog ratio of 1.5:1, and dogs in most households (85.9%, 146/170). Thirty-seven percent (54/146) of those households did not confine their dog(s) to some degree, and 41% (196/472) of surveyed dogs were FRD. Based on multivariable logistic regression models, non-confinement was decreased by (i) negative opinion of owners toward roaming behavior of their dogs, (ii) negative opinion toward FRDs, among others. Dog confinement increased along with owners' concerns about the impacts of their dogs on others. Owned-FRDs tended to have poorer general care than confined dogs. Our findings represent a contribution to the understanding of the human dimensions behind FRDs and provide critical quantitative elements to consider when planning effective control strategies.

Vaccination and monitoring strategies for epidemic prevention and detection in the Channel Island fox (Urocyon littoralis)

Disease transmission and epidemic prevention are top conservation concerns for wildlife managers, especially for small, isolated populations. Previous studies have shown that the course of an epidemic within a heterogeneous host population is strongly influenced by whether pathogens are introduced to regions of relatively high or low host densities. This raises the question of how disease monitoring and vaccination programs are influenced by spatial heterogeneity in host distributions. We addressed this question by modeling vaccination and monitoring strategies for the Channel Island fox (Urocyon littoralis), which has a history of substantial population decline due to introduced disease. We simulated various strategies to detect and prevent epidemics of rabies and canine distemper using a spatially explicit model, which was parameterized from field studies. Increasing sentinel monitoring frequency, and to a lesser degree, the number of monitored sentinels from 50 to 150 radio collared animals, reduced the time to epidemic detection and percentage of the fox population infected at the time of detection for both pathogens. Fox density at the location of pathogen introduction had little influence on the time to detection, but a large influence on how many foxes had become infected by the detection day, especially when sentinels were monitored relatively infrequently. The efficacy of different vaccination strategies was heavily influenced by local host density at the site of pathogen entry. Generally, creating a vaccine firewall far away from the site of pathogen entry was the least effective strategy. A firewall close to the site of pathogen entry was generally more effective than a random distribution of vaccinated animals when pathogens entered regions of high host density, but not when pathogens entered regions of low host density. These results highlight the importance of considering host densities at likely locations of pathogen invasion when designing disease management plans.

Cross-species transmission and evolutionary dynamics of canine distemper virus during a spillover in African lions of Serengeti National Park

The outcome of pathogen spillover from a reservoir to a novel host population can range from a "dead-end" when there is no onward transmission in the recipient population, to epidemic spread and even establishment in new hosts. Understanding the evolutionary epidemiology of spillover events leading to discrete outcomes in novel hosts is key to predicting risk and can lead to a better understanding of the mechanisms of emergence. Here we use a Bayesian phylodynamic approach to examine cross-species transmission and evolutionary dynamics during a canine distemper virus (CDV) spillover event causing clinical disease and population decline in an African lion population (Panthera leo) in the Serengeti Ecological Region between 1993 and 1994. Using 21 near-complete viral genomes from four species we found that this large-scale outbreak was likely  ignited by a single cross-species spillover event from a canid reservoir to noncanid hosts <1 year before disease detection and explosive spread of CDV in lions. Cross-species transmission from other noncanid species probably fuelled the high prevalence of CDV across spatially structured lion prides. Multiple lines of evidence suggest that spotted hyenas (Crocuta crocuta) could have acted as the proximate source of CDV exposure in lions. We report 13 nucleotide substitutions segregating CDV strains found in canids and noncanids. Our results are consistent with the hypothesis that virus evolution played a role in CDV emergence in noncanid hosts following spillover during the outbreak, suggest that host barriers to clinical infection can limit outcomes of CDV spillover in novel host species.

Systematic Review of Important Viral Diseases in Africa in Light of the 'One Health' Concept

Emerging and re-emerging viral diseases are of great public health concern. The recent emergence of Severe Acute Respiratory Syndrome (SARS) related coronavirus (SARS-CoV-2) in December 2019 in China, which causes COVID-19 disease in humans, and its current spread to several countries, leading to the first pandemic in history to be caused by a coronavirus, highlights the significance of zoonotic viral diseases. Rift Valley fever, rabies, West Nile, chikungunya, dengue, yellow fever, Crimean-Congo hemorrhagic fever, Ebola, and influenza viruses among many other viruses have been reported from different African countries. The paucity of information, lack of knowledge, limited resources, and climate change, coupled with cultural traditions make the African continent a hotspot for vector-borne and zoonotic viral diseases, which may spread globally. Currently, there is no information available on the status of virus diseases in Africa. This systematic review highlights the available information about viral diseases, including zoonotic and vector-borne diseases, reported in Africa. The findings will help us understand the trend of emerging and re-emerging virus diseases within the African continent. The findings recommend active surveillance of viral diseases and strict implementation of One Health measures in Africa to improve human public health and reduce the possibility of potential pandemics due to zoonotic viruses.

The Effectiveness of Dog Population Management: A Systematic Review

The worldwide population of domestic dogs is estimated at approximately 700 million, with around 75% classified as "free-roaming". Where free-roaming dogs exist in high densities, there are significant implications for public health, animal welfare, and wildlife. Approaches to manage dog populations include culling, fertility control, and sheltering. Understanding the effectiveness of each of these interventions is important in guiding future dog population management. We present the results of a systematic review of published studies investigating dog population management, to assess: (1) where and when studies were carried out; (2) what population management methods were used; and (3) what was the effect of the method. We evaluated the reporting quality of the published studies for strength of evidence assessment. The systematic review resulted in a corpus of 39 papers from 15 countries, reporting a wide disparity of approaches and measures of effect. We synthesised the management methods and reported effects. Fertility control was most investigated and had the greatest reported effect on dog population size. Reporting quality was low for power calculations (11%), sample size calculations (11%), and the use of control populations (17%). We provide recommendations for future studies to use common metrics and improve reporting quality, study design, and modelling approaches in order to allow better assessment of the true impact of dog population management.

Molecular and serological survey of carnivore pathogens in free-roaming domestic cats of rural communities in southern Chile

Owned, free-roaming domestic cats are abundant in the Chilean countryside, having high probability of contact with wildlife and potentially participating as reservoirs of zoonotic pathogens. In the present study, 131 cats from two remote study areas (Valdivia and Chiloe Island) in southern Chile were analyzed for infection/exposure to eight pathogens. Serum samples from 112 cats were tested for antigens against feline leukemia virus (FeLV antigen-ELISA) and antibodies against feline immunodeficiency virus (FIV-ELISA) and canine distemper virus (CDV-serum neutralization), yielded occurrence of 8.9, 1.7 and 0.8% respectively. The presence of DNA of five vector-borne pathogens, piroplasmids, Ehrlichia spp., Anaplasma spp., Rickettsia spp. and Bartonella spp. was investigated in thirty cats. Overall observed occurrence was 6.6% (2/30) for both Anaplasma platys, and B. henselae, and 3.3% (1/30) for both Bartonella sp. and Theileria equi. Observed occurrence for all vector-borne pathogens in Valdivia area was significantly higher than in Chiloe Island (5/15 vs 0/15; P=0.04). Our results represent the first description of exposure to CDV and DNA detection of T. equi and A. platys in domestic cats in Chile. The results highlight the importance of performing pathogen screening in owned, free-roaming rural cats to evaluate their potential role as reservoirs of infection and vectors for disease transmission to wildlife.

Canine and Phocine Distemper Viruses: Global Spread and Genetic Basis of Jumping Species Barriers

Canine distemper virus (CDV) and phocine distemper (PDV) are closely-related members of the Paramyxoviridae family, genus morbillivirus, in the order Mononegavirales. CDV has a broad host range among carnivores. PDV is thought to be derived from CDV through contact between terrestrial carnivores and seals. PDV has caused extensive mortality in Atlantic seals and other marine mammals, and more recently has spread to the North Pacific Ocean. CDV also infects marine carnivores, and there is evidence of morbillivirus infection of seals and other species in Antarctica. Recently, CDV has spread to felines and other wildlife species in the Serengeti and South Africa. Some CDV vaccines may also have caused wildlife disease. Changes in the virus haemagglutinin (H) protein, particularly the signaling lymphocyte activation molecule (SLAM) receptor binding site, correlate with adaptation to non-canine hosts. Differences in the phosphoprotein (P) gene sequences between disease and non-disease causing CDV strains may relate to pathogenicity in domestic dogs and wildlife. Of most concern are reports of CDV infection and disease in non-human primates raising the possibility of zoonosis. In this article we review the global occurrence of CDV and PDV, and present both historical and genetic information relating to these viruses crossing species barriers.

Host Specificity in Variable Environments

Host specificity encompasses the range and diversity of host species that a parasite is capable of infecting and is considered a crucial measure of a parasite's potential to shift hosts and trigger disease emergence. Yet empirical studies rarely consider that regional observations only reflect a parasite's 'realized' host range under particular conditions: the true 'fundamental' range of host specificity is typically not approached. We provide an overview of challenges and directions in modelling host specificity under variable environmental conditions. Combining tractable modelling frameworks with multiple data sources that account for the strong interplay between a parasite's evolutionary history, transmission mode, and environmental filters that shape host-parasite interactions will improve efforts to quantify emerging disease risk in times of global change.

Assessing the natural circulation of canine vector-borne pathogens in foxes, ticks and fleas in protected areas of Argentine Patagonia with negligible dog participation

We collected blood and/or ectoparasites from 49 South American grey foxes (Lycalopex griseus) and two Andean foxes (L. culpaeus) caught in two National Parks of southern Argentine Patagonia (Bosques Petrificados, BPNP; and Monte León, MLNP) where dogs are nearly absent (density < 0.01 dog/km2). Common ectoparasites were the flea Pulex irritans (88% prevalence) and the tick Amblyomma tigrinum (29%). Conventional PCR and sequencing of 49 blood samples, 299 fleas analysed in 78 pools, and 21 ticks revealed the presence of DNA of the following canine vector-borne pathogens: in grey foxes, Rickettsia sp. (3%), hemoplasmas (8%), including Mycoplasma haemocanis, and Hepatozoon sp. (50%); in P. irritans, Bartonella spp. (72% of flea pools from 76% of foxes), mostly B. vinsonii subsp. berkhoffii but also B. rochalimae, Anaplasmataceae (Wolbachia sp.; 60% and 54%), and M. haemocanis/haemofelis (29% and 18%); and in A. tigrinum, Hepatozoon sp. (33% of ticks in 4 of 7 foxes). No piroplasmid DNA was detected in any sample. Andean foxes were negative for all tested pathogens. Two different Hepatozoon haplotypes were detected: the most prevalent was phylogenetically associated with H. felis, and the other with H. americanum and related sequences. Amblyomma tigrinum and Hepatozoon sp. were more abundant and/or prevalent in BPNP than in colder MLNP, 300 km southwards, perhaps located close to the limit for tick suitability. Bartonella v. berkhoffii was also significantly more prevalent in fleas of foxes in BPNP than in MLNP. This study provides novel information about natural host-pathogen associations in wildlife, markedly extends the distribution area in South America of arthropods and vector-borne pathogens of veterinary and public health interest, and contributes preliminary evidence about the potential role of A. tigrinum and P. irritans as vectors, respectively, for potentially new species of Hepatozoon from Lycalopex spp. and for M. haemocanis that should be further investigated.

New world origin of canine distemper: Interdisciplinary insights

OBJECTIVE

Canine distemper virus (CDV), human measles virus (HMV), and rinderpest virus (RPV) of cattle are morbilliviruses that have caused devastating outbreaks for centuries. This paper seeks to reconstruct the evolutionary history of CDV.

MATERIALS AND METHODS

An interdisciplinary approach is adopted, synthesizing paleopathological analysis of 96 Pre-Columbian dogs (750-1470 CE) from the Weyanoke Old Town, Virginia site, with historical reports, molecular analysis and morbilliviral epidemiology.

RESULTS

Both measles (c.900CE) and rinderpest (c. 376 BCE) were first reported in Eurasia, while canine distemper was initially described in South America much later (1735 CE); there are no paleopathological indications of CDV in Weyanoke Old Town dogs. Molecularly, CDV is closely related to HMV, while viral codon usage indicates CDV may have previously infected humans; South American measles epidemics occurred prior to the emergence of canine distemper and would have facilitated HMV transmission and adaptation to dogs.

CONCLUSIONS

The measles epidemics that decimated indigenous South American populations in the 1500-1700 s likely facilitated the establishment of CDV as a canine pathogen, which eventually spread to Europe and beyond.

SIGNIFICANCE

Understanding the historical and environmental conditions that have driven morbilliviral evolution provides important insights into potential future threats of animal/human cross-species infections.

LIMITATIONS

Interpreting historical disease descriptions is difficult and the archaeological specimens are limited. Molecular sequence data and codon usage analyses rely on modern viruses.

SUGGESTIONS FOR FURTHER RESEARCH

Interdisciplinary approaches are increasingly needed to understand diseases of the past and present, as critical information and knowledge is scattered in different disciplines.

Challenges and Opportunities Developing Mathematical Models of Shared Pathogens of Domestic and Wild Animals

Diseases that affect both wild and domestic animals can be particularly difficult to prevent, predict, mitigate, and control. Such multi-host diseases can have devastating economic impacts on domestic animal producers and can present significant challenges to wildlife populations, particularly for populations of conservation concern. Few mathematical models exist that capture the complexities of these multi-host pathogens, yet the development of such models would allow us to estimate and compare the potential effectiveness of management actions for mitigating or suppressing disease in wildlife and/or livestock host populations. We conducted a workshop in March 2014 to identify the challenges associated with developing models of pathogen transmission across the wildlife-livestock interface. The development of mathematical models of pathogen transmission at this interface is hampered by the difficulties associated with describing the host-pathogen systems, including: (1) the identity of wildlife hosts, their distributions, and movement patterns; (2) the pathogen transmission pathways between wildlife and domestic animals; (3) the effects of the disease and concomitant mitigation efforts on wild and domestic animal populations; and (4) barriers to communication between sectors. To promote the development of mathematical models of transmission at this interface, we recommend further integration of modern quantitative techniques and improvement of communication among wildlife biologists, mathematical modelers, veterinary medicine professionals, producers, and other stakeholders concerned with the consequences of pathogen transmission at this important, yet poorly understood, interface.

Endoparasites in domestic animals surrounding an Atlantic Forest remnant, in São Paulo State, Brazil

Morro do Diabo State Park (MDSP) is a significant remnant of the Atlantic Rain Forest in Brazil and is surrounded by rural properties. In that area, wild and domestic animals and humans are in close contact, which facilitates the two-way flow of infectious diseases among them. We assessed endoparasites in domestic livestock from all rural properties surrounding MDSP. There were sampled 197 cattle, 37 horses, 11 sheep, 25 swine, 21 dogs, one cat and 62 groups of chickens from 10 large private properties and 75 rural settlements. Eimeria spp. was present in almost all hosts, excepted in horses, dogs and cats. Giardia cysts were present only in cattle. Nematodes were found in swine, ruminants and horses in high prevalence. Ancylostoma, Toxocara and Sarcocystis were found in dogs. Chickens were found with coccidia, Ascaridida and Capillaria spp.. These parasites can cause malnutrition and reproductive disorders for their hosts. Strategies to prevent and control the spread of endoparasites can improve wildlife, animal and human health in this area.

Estimating Loss of Brucella Abortus Antibodies from Age-Specific Serological Data In Elk

Serological data are one of the primary sources of information for disease monitoring in wildlife. However, the duration of the seropositive status of exposed individuals is almost always unknown for many free-ranging host species. Directly estimating rates of antibody loss typically requires difficult longitudinal sampling of individuals following seroconversion. Instead, we propose a Bayesian statistical approach linking age and serological data to a mechanistic epidemiological model to infer brucellosis infection, the probability of antibody loss, and recovery rates of elk (Cervus canadensis) in the Greater Yellowstone Ecosystem. We found that seroprevalence declined above the age of ten, with no evidence of disease-induced mortality. The probability of antibody loss was estimated to be 0.70 per year after a five-year period of seropositivity and the basic reproduction number for brucellosis to 2.13. Our results suggest that individuals are unlikely to become re-infected because models with this mechanism were unable to reproduce a significant decline in seroprevalence in older individuals. This study highlights the possible implications of antibody loss, which could bias our estimation of critical epidemiological parameters for wildlife disease management based on serological data.

Advances in canine distemper virus pathogenesis research: a wildlife perspective

Canine distemper virus (CDV) has emerged as a significant disease of wildlife, which is highly contagious and readily transmitted between susceptible hosts. Initially described as an infectious disease of domestic dogs, it is now recognized as a global multi-host pathogen, infecting and causing mass mortalities in a wide range of carnivore species. The last decade has seen the effect of numerous CDV outbreaks in various wildlife populations. Prevention of CDV requires a clear understanding of the potential hosts in danger of infection as well as the dynamic pathways CDV uses to gain entry to its host cells and its ability to initiate viral shedding and disease transmission. We review recent research conducted on CDV infections in wildlife, including the latest findings on the causes of host specificity and cellular receptors involved in distemper pathogenesis.