The Importance of Entomo-Virological Investigation of Yellow Fever Virus to Strengthen Surveillance in Brazil.

The largest outbreak of sylvatic yellow fever virus (YFV) in eight decades was recorded in Brazil between 2016-2018. Besides human and NHP surveillance, the entomo-virological approach is considered as a complementary tool. For this study, a total of 2904 mosquitoes of the , and genera were collected from six Brazilian states (Bahia, Goiás, Mato Grosso, Minas Gerais, Pará, and Tocantins) and grouped into 246 pools, which were tested for YFV using RT-qPCR. We detected 20 positive pools from Minas Gerais, 5 from Goiás, and 1 from Bahia, including 12 of and 5 of . This is the first description of natural YFV infection in this species and warns of the likelihood of urban YFV re-emergence with as a potential bridge vector. Three YFV sequences from from Goiás and one from Minas Gerais, as well as one from from Minas Gerais were clustered within the 2016-2018 outbreak clade, indicating YFV spread from Midwest and its infection in a main and likely novel bridging vector species. Entomo-virological surveillance is critical for YFV monitoring in Brazil, which could highlight the need to strengthen YFV surveillance, vaccination coverage, and vector control measures.