Ecohealth最新文献

Ranavirosis is an emerging infectious disease of amphibians, fish, and reptiles caused by large dsDNA viruses of the genus Ranavirus associated with morbidity and mass mortalities worldwide. They are considered to be one of the major drivers of the ongoing amphibian biodiversity crisis. In this study, we investigated the prevalence and genetic diversity of ranaviruses in native and invasive populations of water frogs (Pelophylax spp.) across Russia using the DNA sample collection established in 2006-2016. The collection included samples collected in the wild and samples from wild-caught water frogs that had been kept in laboratories for a period of time. Overall, 52 out of 590 (8.8%) of wild frogs from 18 out of 94 (19.1%) sampling sites tested positive, including samples from invasive populations. Among the captive frogs, 71 out of 263 (27.0%) were positive and they had a significantly higher relative viral load. We found six major capsid protein gene haplotypes from 22 positive samples, all belonging to the common midwife toad virus (CMTV-like) ranaviruses, at multiple sites within the basins of three of Europe's largest rivers (Volga, Dnieper, and Don). Combined with previously published data, this study provides evidence for a continent-wide distribution of CMTV-like ranaviruses in Europe and strengthens the hypothesis of their endemism on the continent. Our study also highlights that the water frogs are important hosts for ranaviruses and could potentially act as vectors for infection transmission.

Habitat degradation induced by human activities can exacerbate the spread of wildlife disease and could hinder the recovery of imperiled species. The endangered green turtle Chelonia mydas is impacted worldwide by fibropapillomatosis (FP), a neoplastic infectious disease likely triggered by the Scutavirus chelonidalpha5 with coastal anthropogenic stressors acting as cofactors in disease development. Here, we studied fibropapillomatosis dynamics and its demographic consequences using an 11-year capture-mark-recapture dataset in Anse du Bourg d'Arlet/Chaudière (ABAC) and Grande Anse d'Arlet (GA), two juvenile green turtle foraging grounds in Martinique, French West Indies. Afflicted turtles had similar mortality and permanent emigration rates to the non-afflicted ones. Fibropapillomatosis was commonly observed in large individuals and disease recovery may take several years. Consequently, permanent emigration before full recovery from the disease is suspected and might affect the developmental migration success. Additionally, the results revealed that the FP had higher prevalence and severity, and progressed two times faster in ABAC than in GA despite the proximity (< 2 km) and the similarity of the two foraging grounds. The reasons for these differences remain unidentified. Locally, further studies should be focused on the determination of the external and internal cofactors related to the observed FP dynamics. Finally, the investigations should be extended at a global regional scale to determine potential deleterious effect of the FP on the adult life-stage. These perspectives improves upon our overall understanding on the interplay between wildlife diseases, hosts and environmental factors.

Land-use change and increased human-livestock-wildlife interactions have generated numerous possibilities for viral spillover, demanding enhanced surveillance in biodiverse regions. We investigated adenovirus diversity in small mammals, an understudied host taxon, from a forest-plantation mosaic in the Western Ghats biodiversity hotspot. We observed high prevalence (up to 39.39%) and identified five lineages of adenoviruses with unique mutations in the dominant small mammal species, Rattus satarae. These lineages significantly differed from other known murine adenoviruses (p-distance > 25%), indicating the likelihood of novel adenoviruses in this endemic small mammal and suggesting potential for unexplored DNA virus diversity in the region.

Our aim was to investigate respiratory viruses circulating in animals from the urban Atlantic Forest, which is located in the most densely populated area near Rio de Janeiro in Brazil. This study focused on the detection of Influenza A viruses and diverse coronaviruses, including SARS-CoV-2, in domestic and wild animals, including bats, nonhuman primates, rodents, and marsupials. From August 2020 to September 2022, biological samples were collected from a total of 72 pets, 66 primates, 20 rodents, 36 marsupials, and 390 bats. Samples were tested using RT-PCR for Influenza A and coronaviruses, and positive samples were sequenced. When blood samples were available, they were tested for SARS-CoV-2 antibodies. All terrestrial animals were negative for evidence of infection with SARS-CoV-2 and Influenza A viruses. However, samples from 17 phyllostomid bats, including Great fruit-eating bat (Artibeus lituratus), Silky short-tailed bat (Carollia brevicauda), Seba's short-tailed bat (Carollia perspicillata), Common big-eared bat (Micronycteris microtis), Greater spear-nosed bat (Phyllostomus hastatus), White-lined broad-nosed bat (Platyrrhinus lineatus), Little yellow-shouldered bat (Sturnira lilium), Greater round-eared bat (Tonatia bidens), and Common vampire bat (Desmodus rotundus), were positive for bat coronaviruses classified as Alphacoronavirus. Our study adds new information on the occurrence of coronaviruses in bats and contributes to a long-term program of Influenza surveillance. Developing active surveillance for viruses in wildlife species, as implemented in this study, is crucial for understanding zoonotic risks and preventing future global pandemics.

Chytridiomycosis is a wildlife disease that has caused significant declines in amphibian populations and species extinctions worldwide. Asia, where the causal pathogens Batrachochytrium dendrobatidis (Bd) and B. salamndrivorans (Bsal) originated, has not witnessed mass die-offs. It is hypothesized that Asian amphibians may have evolved immunity to clinical Batrachochytrium infection, but this has not been explored in depth due to limited knowledge of endemic lineages and infection patterns. We investigated Bd's genetic diversity and infection patterns in south China's Guangxi region using the internal transcribed spacer (ITS) marker and nested PCR. Across the 17 forest sites studied (N = 1088 individuals; 1012 adults and 76 tadpoles), the overall prevalence of Bd infection was 4.74% in adult individuals and 5.26% in tadpoles. We found seven new haplotypes, four of which were closely related to the BdASIA-1 lineage from South Korea. The most prevalent haplotype (genetically similar to BdASIA-3) was found in 11 out of 15 infected species, including a salamander with non-lethal skin lesions. A generalized linear model of our environmental data indicates that Bd infection is correlated with mean temperature of the warmest quarter and elevation, with higher infection prevalence associated with lower temperature and relatively higher elevation in southern China. Our findings suggest significant undiscovered genetic diversity of Asian Bd lineages in this region. Longer-term studies are required to further investigate Bd diversity, prevalence, seasonality, and impact on native species and populations in Southern China and across the region of origin in Asia.

Anthropogenic disturbances degrade ecosystems, elevating the risk of emerging infectious diseases from wildlife. However, the key environmental factors for preventing tick-borne disease infection in relation to host species, landscape components, and climate conditions remain unknown. This study focuses on identifying crucial environmental factors contributing to the outbreak of severe fever with thrombocytopenia syndrome (SFTS), a tick-borne disease, in Miyazaki Prefecture, southern Japan. We collected data on SFTS case numbers, annual temperature and precipitation, species richness of large- and middle-sized mammals, forest perimeter length (indicating the amount of forest boundaries), percentage of agricultural land, human population, and sightseeing place numbers for each 25 km² grid cell encompassing Miyazaki Prefecture. Through the construction of a model incorporating these factors, we found that longer forest perimeter and higher temperature led to a higher number of SFTS cases. Precipitation, mammal species richness, percentage of agricultural land, human population, and sightseeing point numbers had no effect on SFTS case numbers. In conclusion, climate condition and forest fragmentation, which increase the opportunity for human infection, played a pivotal role in SFTS outbreak.

The black rat Rattus rattus is an exotic and synanthropic rodent prominent in Brazil and with high adaptation to urban areas. The species have an omnivorous diet feed on human food resources, potentially becoming infected and spreading infectious agents that cause zoonoses such as leptospirosis, leishmaniosis, Chagas disease, and toxoplasmosis, which are significant public health concerns in the country. We analyzed the epidemiologic profile of R. rattus infected with these agents using molecular diagnostics in the Olivença district, known for its tourism potential, in Ilhéus, Bahia, Brazil. Of 140 animals, the prevalence rates were 30.0% (42) for Leptospira spp., 3.57% (5) for Leishmania spp., and 0.71% (1) for both Trypanosoma cruzi and Toxoplasma gondii. One animal was co-infected with Leptospira interrogans and T. gondii and another with Leptospira spp. and L. (L.) infantum. The high prevalence of Leptospira spp.-infected animals suggests rodents may be a significant infection source for local hosts, as L. interrogans is most common in rodents and humans. Rodents likely become infected through ingestion or contact with contaminated water bodies or food, particularly for Leptospira spp. and T. gondii. It is worth noting that the studied area has beach, high foot traffic, and popular tourist restaurants, which implies the presence of food waste and litter in the environment. This study found synanthropic rodents infected with significant zoonotic agents, indicating their presence in the environment. These agents may not impact the rodent population but can cause serious diseases in humans and other domestic and wild animal species.

SARS-CoV-2 has been found in multiple species, including cervids such as wild white-tailed deer (WTD), in multiple regions in the United States, including Illinois. The virus has been shown to transmit among WTD, and across species in both directions (deer-to-humans and humans-to-deer). Cross-species transmission requires infectious contact between WTD and humans, the form and frequency of which is poorly understood. The aim of this cross-sectional survey was to understand the frequency and type of contact between the general public in the state of Illinois and WTD, and to identify human populations at highest risk for such contact. An online survey was distributed using convenience sampling from list serves, social media, and community partners or extension liaisons. Questions addressed frequency and distance of contact with WTD, encompassing live animals and bodily fluids. Standard and ordinal logistic regression were used to identify factors associated with contact. An overall risk score was calculated, and linear regression was used to identify factors associated with risk. We found that hunters and those who have deer feeding on their property are more likely to report contact with deer, and that people reporting a larger lot size and living in counties with higher proportions of potential deer habitat are more likely to report deer feeding on their property. These results will better identify people with a high likelihood of WTD contact for messaging and further research. Our survey did not distinguish between contact with live and dead WTD, thus the findings are most relevant to deer-to-human cross-species transmission than the human-to-deer direction.

Urban domestic dog populations can provide important clues about the eco-epidemiological characteristics of Trypanosoma cruzi, the causative agent of Chagas disease (ChD). Given the limited data on ChD from the Metropolitan Area of Mendoza, Argentina, a seroprevalence survey of 327 dogs across an urban-rural gradient was conducted between April 2018 and May 2019. Seropositive cases were analyzed considering host, social, and environmental factors, subtypes (DTUs), and bloodstream parasite load. Seroprevalence of infection by T. cruzi total antigens (ELISA-H) was similar in urban (18%), interface (14%), and rural (21%) areas. Serotyping (recombinant TSSA-II antigen ELISA) revealed that 61% (37/61) of seropositive dogs carried the subtypes TcII, V and/or VI. There was no difference in the proportion of seropositive dogs versus seronegative dogs that lived with a person with ChD (9/62 = 14% vs. 35/265 = 13%, respectively). Parasite loads in seropositive dogs varied between < 0.10 and 1.18 parasite-equivalents/ml. Dogs with T. cruzi infection were in good health and nutritional condition, suggesting that they may have indeterminate or chronic stage infections. High infection rates in all areas and limited knowledge of owners about ChD and its triatomine vectors emphasize the need to intensify entomological studies, especially in urban areas, and promote vector information campaigns. This work shows that screening of dogs is a beneficial epidemiological tool to deepen studies on ChD from a One Health perspective.