Ranavirus infection in anuran species in Atlantic Forest fragments in Brazil

Ranaviruses (RVs) are emerging pathogens that infect amphibians, reptiles, and fish, and have been linked to declines in several anuran species globally. Assessing their prevalence in wild populations is essential for effective monitoring and conservation efforts. This study evaluates the prevalence of RV in anurans from forest fragments in the Atlantic Forest in Brazil. We investigated the presence of RV in tissue samples obtained from 203 anurans, which included metamorphosed individuals and tadpoles of native species and the invasive American bullfrog. Additionally, we collected water from ponds to assess the presence of RV in the environment (using eDNA). We performed quantitative real-time PCR assays targeting the major capsid protein (MCP)-encoding region of RV to evaluate the potential risk posed by RV within these communities. The analysis revealed the presence of viral DNA in 3 of 5 sites and an overall prevalence of 60% in the animals. Our results show that RV is widespread and prevalent among wild amphibians living in fragments of the Atlantic Forest. Our findings highlight the potential threat posed by RVs as an emerging disease.