Rabies in free-ranging capybaras (Hydrochoerus hydrochaeris) on Anchieta Island, Ubatuba, Brazil.

Abstract

Between December 2019 and January 2020, three cases of rabies were reported in free-ranging capybaras on Anchieta Island, Ubatuba-SP, Brazil. This 8.28 km² island is located 540 m offshore from the mainland. Two of the capybaras exhibited signs of hindlimb paralysis, and one was found dead. Rabies was diagnosed using the direct fluorescent antibody test (dFAT), while RT-qPCR and phylogenetic analysis of nucleotide sequences confirmed the presence of the vampire bat rabies virus (RABV) strain. Although no visible bat bite marks were found on the capybaras, vampire bats are known to inhabit the island. Other wildlife tested negative for rabies during this period, and no further rabies outbreaks have been observed since. Environmental changes and human activities, such as the disturbance of bat roosting sites, may have contributed to the incident. The detection of rabies in capybaras suggests a potential spillover from a vampire bat reservoir. Further investigation is needed to determine whether capybaras act as dead-end hosts or play a role in maintaining the rabies transmission cycle.