Seroprevalence of rabies virus antibodies in bats from high risk areas in Brazilian Amazonia between 2013 and 2015.

Background: The outbreaks of human rabies that occurred between 2004 and 2005 in the Brazilian Amazon highlight the importance of bats in the transmission of this zoonosis. Ten years after, this region is still considered to be a risk area.

Methods: Serum and brain tissue samples were obtained from bats captured between 2013 and 2015. The sera were tested for the presence of rabies antibodies, using the rapid fluorescent focus inhibition test, and the brain tissue samples were tested for the presence of the rabies antigen by the direct immunofluorescence method and intracerebral inoculation in mice.

Results: A total of 64% (148/230) of the serum samples were seropositive, although none of the brain samples were positive for rabies infection. The seroprevalence was significantly higher in the second year of the study (p<0.001). This figure was detected in all variables (sex, age, season) and in most of the bat species.

Conclusions: Our results indicate the possible occurrence of a recent peak in infection by the rabies virus in these bat populations, which represents an important alert, given that attacks by hematophagous bats are a constant threat in the study area, contributing to the probability of the occurrence of new cases of rabies.