Arbovirus Investigation in Free-Living Bats in Midwest Brazil, 2017–2018

Abstract Epidemic arboviruses such as dengue (DENV), zika (ZIKV), and chikungunya (CHIKV) are maintained between humans and Aedes aegypti mosquitoes and have great impact on public health in Brazil. In addition to these epidemic arboviruses, enzootic arboviruses such as yellow fever (YFV), mayaro (MAYV), and oropouche (OROV) viruses, that circulate between wildlife and bloodsucking dipterans, are also of great medical concern in the country. If these viruses circulate in synanthropic vertebrate species, and if these animals play a role in arboviruses transmission cycles, remains unclear. Bats are commonly found in large populations at the animal–human interface, so their exposure to arboviruses merits continuous surveillance. Between 2017 and 2018, we investigated the circulation of Brazil’s important arboviruses in bats (n=189) collected at the human–animal interface areas of Midwest Brazil. Carollia perspicillata and Artibeus lituratus were the most common species captured. Using RT-qPCR assays, we conducted a molecular screening for DENV, ZIKV, CHIKV, YFV, MAYV, and OROV RNA in liver, kidney, and brain samples of free-ranging bats . Additionally, plasma of 79 bats were tested by plaque reduction neutralization test (PRNT) for specific neutralizing antibodies for OROV and plasma of 73 bats were tested for MAYV. All tissue specimens tested negative by RT-qPCR suggesting no current infections by any of the arboviruses tested. All bats presented PRNT 90 titer <20 for OROV and MAYV and therefore considered seronegative. Plaque reduction below the predefined threshold for seropositivity for MAYV was observed in several individuals and merits further investigation. Plasma samples from 67 other bats also presented plaque reduction for MAYV that could not be confirmed due to limited sample volume for serial dilution in PRNT. The absence of active infection by arboviruses associated with the large number of bats presenting plaque reduction for MAYV merits further investigation.