Mosquito-borne viruses in São Paulo, Brazil: Diversity, Distribution, and Public Health Challenges

Mosquitoes are major vectors of public health concern, capable of transmitting viruses, bacteria, and parasites. In Brazil, more than 210 arboviral strains have been isolated, many of which are pathogenic to humans. Within this context, the State of São Paulo (SSP) stands out as the most populous state in the country and an important hub for national and international mobility. The state also preserves extensive remnants of the Atlantic Forest, one of the world's major biodiversity hotspots. These ecological conditions favor the maintenance and circulation of a wide diversity of mosquitoes, arboviruses, and potential host species.

This study compiles all records of mosquito-borne viruses detected in SSP and analyzes their spatial and temporal distribution from 1889 to 2025.

Over the past 136 years, 43 distinct mosquito-borne viruses have been identified, predominantly belonging to the families Peribunyaviridae, Flaviviridae, and Togaviridae. Some were detected exclusively from mosquitoes, particularly from the genera Aedes, Culex, Anopheles, Haemagogus, and Sabethes. Vertebrate detections were most frequent in wild birds, rodents, and non-human primates, with additional records in cattle, horses, coatis, bats, dogs, and marsupials; however, their role in viral maintenance remains uncertain given the heterogeneity of evidence.

Viruses were predominantly concentrated in southeastern SSP, especially within Atlantic Forest fragments. The data highlight complex ecological interactions among viruses, vectors, and hosts across urban, rural, and protected landscapes, revealing both the persistence of endemic pathogens, such as dengue and chikungunya viruses, and the emergence or re-emergence of other arboviruses. These findings underscore the importance of ongoing, multidisciplinary surveillance to anticipate and mitigate future arboviral outbreaks in the state.