Nature Microbiology | Evolution and spillover dynamics of yellow fever at the forest–urban interface in Brazil
Juliana Telles-de-Deus, Ingra M. Claro, Mayara Bertanhe, Charles Whittaker, Márcio Port-Carvalho, Esmenia C. Rocha, Thaís M. Coletti, Camila A. M. da Silva, Ian Nunes Valença, Tamara N. Lima-Camara, Márcia Bicudo de Paula, Mariana S. Cunha, Jaqueline G. de Jesus, Pâmela dos Santos Andrade, Victoria Cox, Natalia C. C. F. de Azevedo, Juliana M. Guerra, Juliana L. Summa, Ana Paula P. Teixeira, Eduardo S. Bergo, Mariza Pereira, Filipe R. R. Moreira, Alvina Clara Felix, Anderson V. de Paula, …Nuno R. Faria
DOI: https://doi.org/10.1038/s41564-026-02302-w
Background
Yellow fever virus (YFV) continues to threaten human and wildlife populations in the Americas, yet its transmission at the forest–urban interface remains unclear.
Methods
This study integrate ground- and canopy-level mosquito surveillance, systematic monitoring of non-human primate carcasses, and viral metagenomics to describe the dynamics of a sylvatic YFV outbreak in a 186-hectare Atlantic Forest fragment embedded within metropolitan São Paulo, Brazil, between 2017 and 2018.
Results
The analyses reveal that transmission was primarily driven by a single genetic cluster introduced during a period of high abundance of the main vector, Haemagogus leucocelaenus mosquitoes. A near-complete hepatitis A virus genome was detected in a YFV-infected howler monkey, suggesting potential co-infections at the human–wildlife interface. Phylogenetic and epidemiological modelling estimated a basic reproduction number (R0) for sylvatic yellow fever of 8.2 (95% CI 5.1–12.2), substantially higher than previous estimates for urban outbreaks.
Fig. 1 Spatial and temporal context of the YFV epizootic in PEAL’s State Park (São Paulo, Brazil).
Fig. 2 Relationship between RT–PCR Ct values, viral load, timing of observations and viral detection.
Fig. 3 Temporal dynamics of YFV cluster introductions in PEAL State Park.
Fig. 4 Empirical and estimated distributions informing key temporal parameters of YFV epidemic dynamics in a sylvatic cycle.
Fig. 5 Transmission dynamics and epidemic potential of sylvatic YFV in PEAL.
Conclusion
The findings demonstrate that multisource surveillance could provide actionable early warnings in regions at risk for zoonotic spillover.
Reference
Telles-de-Deus, J., Claro, I.M., Bertanhe, M. et al. Evolution and spillover dynamics of yellow fever at the forest–urban interface in Brazil. Nat Microbiol (2026). https://doi.org/10.1038/s41564-026-02302-w
