Early insights of dengue virus serotype 3 (DENV-3) re-emergence in São Paulo, Brazil

This work aimed to characterize and provide preliminary insights into dengue virus serotype 3 (DENV-3) re-emergence in São Paulo state, Brazil. We conducted active arbovirus molecular surveillance on samples from patients with acute febrile illness combined with next-generation sequencing and phylogenetic analyses. We detected and characterized DENV-3 circulation in São Paulo, Brazil, since late 2023. The genomes clustered within genomes recently (2022-2024) identified in Florida, the Caribbean region, and Brazil. Our results demonstrate the resurgence of DENV-3 in the region since 2009, raising concerns about a potential outbreak in regions with a high epidemic history.