Coxiella burnetii in free-living feral pigs (Sus scrofa) in Brazil

BACKGROUND: Coxiella burnetii, the etiological agent of coxiellosis in animals and Q fever in humans, is a zoonotic pathogen of global relevance that can infect a wide range of species. Although several domestic and wild animals are involved in the natural cycle, the role of wildlife hosts remains poorly understood. OBJECTIVES: Our study aimed to investigate the presence of C. burnetii in feral pigs hunted in Brazilian Pantanal wetland. METHODS: In this study, 36 free-living feral pigs legally hunted in Mato Grosso State, Brazil, were sampled. Sera were tested by enzyme-linked immunosorbent assay (ELISA), and spleen, liver, sera and tick samples were analysed by polymerase chain reaction (PCR). FINDINGS: Serological evidence of exposure was detected in 22.2% [8/36; 95% confidence interval (CI): 11.7% - 38.1%], while C. burnetii DNA was found in one spleen sample (1/36 - 2.8%; 95% CI: 0.1% - 14.5%). Only Coxiella-like endosymbiont was detected in Amblyomma sculptum ticks (9/23 - 39.13%; 95% CI: 22.2% - 59.2%). MAIN CONCLUSIONS: These results represent the first detection of C. burnetii in free-living feral pigs in Brazil and suggest potential exposure of this invasive mammal species to the pathogen. The findings underscore the need for broader surveillance of C. burnetii at the wildlife-livestock-human interface in Brazil.