Investigation of RNA viral pathogens in wild carnivores killed by vehicular collisions on roads highways in the state of São Paulo

• Ano de defesa: 2024
• Autor(a) principal: Lugo, Maria Alejandra Arias
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Atropelamento; Carnívoros selvagens; Conservação; Conservation; RNA viroses; Roadkill; Vírus de RNA; Wild carnivores
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/10/10133/tde-20062024-141149/

Sixty-nine species of wild mammals are officially classified as threatened of extinction in Brazil, which represents 10.6% of 652 native species. The orders with the highest proportions of threatened species are Primates and Carnivora. Human activities, resource depletion, and climate change fuel a dangerous rise on transmission of several pathogens, increasing the risk of diseases with potentially harmful outcomes. Many studies have reported the flow of pathogens among domestic animals, wildlife, and humans, leading to consequences such as epizootics or pandemics. Specifically, among domestic and wild carnivores, some diseases have already been reported, including distemper, parvovirus, rabies, leishmaniasis and dirofilariosis. To enhance the knowledge about the occurrence of pathogens in wild carnivores, this dissertation aimed to study by molecular and anatomopathological methods the presence of four RNA virus agents: Canine Distemper Virus (CDV), SARS-CoV-2, Feline Coronavirus (FCoV) and Rabies Virus (RABV). For this, carcasses of roadkilled wild carnivores on roads in the state of São Paulo were collected. A necropsy was performed looking for gross changes suggestive of the diseases caused by the studied viruses. Additionally, fragments of organs were collected, fixed in 10% formalin, and routinely processed to make slides stained with H&E for subsequent histopathological analysis in search of microscopic changes consistent with the viral agents studied, for those cases where the molecular assays were positive. For each viral agent, samples from the target organ were collected: CDV (lung, central nervous system, kidney, and intestine), SARS-CoV-2 (lung), FCoV (intestine) and RABV (central nervous system), and conventional polymerase chain reaction (PCR) or real-time polymerase chain reaction (RT-PCR) tests were performed. In total, 33 carcasses were collected representing four species of felids (Herpailurus yagouaroundi, Leopardus Pardalis, Puma concolor, Leopardus guttulus), three of mustelids (Lontra longicaudis, Galictis cuja, Eira barbara), two of canids (Cerdocyon thous and Chrysocyon brachyurus), and two of procyonids (Nasua nasua and Procyon cancrivorus). Through anatomopathological analyses, no changes (gross or microscopic) suggestive of the diseases caused by the agents studied were observed. Likewise, molecular screening showed that all cases were negative for all tests carried out. It is concluded that there was no evidence of the presence of these viruses in the animals studied; therefore our sampling allows us to infer that in the study area these viral agents do not appear to be, at this time, a threat to the conservation of wild carnivores. However, due to the species diversity in this study, we consider that unnatural mortality by roadkills may be important for the loss of apparently healthy individuals. Finally, we highlight the importance of increasing the implementation of mitigation measures on roads in the state of São Paulo.