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

Abstract

Background: In dengue hyperendemic regions, the evolution of the virus is marked by frequent virus introduction/reintroduction and clade replacement events, occasionally linked to an epidemic outbreak. From 2023 onwards, an increase in the detection of DENV-3 cases has been reported in different regions of Brazil. Thus, molecular and genomic surveillance of circulating DENV strains is crucial for public health preparedness and response efforts for the disease. Objectives: This work aimed to characterize and provide preliminary insights into dengue virus serotype 3 (DENV-3) re-emergence in São Paulo state, Brazil. Study design: We conducted active arbovirus molecular surveillance on samples from patients with acute febrile illness combined with next-generation sequencing and phylogenetic analyses. Results: 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. Conclusions: 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.