Ranavirus causes 83% decline in native Brazilian leaf frog population

A study published in the journal ‘Biodiversity and Conservation’ has confirmed the first case of mass amphibian deaths caused by ranavirus in South America. Researchers from the Federal University of Paraná (UFPR) and Unicamp found that recurrent outbreaks of the virus led to an 83% population decline in the leaf frog (Phyllomedusa distincta), a species native to Brazil’s Atlantic Forest.

The research, conducted in a preservation lagoon in Guaramirim, Santa Catarina, identified that between 2024 and 2026, three outbreaks resulted in the deaths of 324 tadpoles. Approximately 88% of the tested animals showed high viral loads, with histological analyses revealing severe tissue lesions, necrosis, and hemorrhaging in vital organs.

Experts note that transmission is accelerated during dry periods, as low humidity weakens the amphibians' immune systems and receding water levels concentrate animals in smaller areas, facilitating contagion. Because amphibians serve as ‘environmental sentinels,’ their decline signals broader ecological issues. Monitoring remains active at the Santuário Rã-Bugio Private Natural Heritage Reserve to assess the virus's presence in surrounding regions.