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[Preprint]. 2025 Apr 12:2025.04.10.25325467.
doi: 10.1101/2025.04.10.25325467.

Re-emergence of Yellow Fever Virus in Brazil: Evidence from Forest and peri-urban Settings

Valnete das Graças Dantas Andrade  1 , Talita Émile Ribeiro Adelino  2   3 , Vagner Fonseca  4 , Keldenn Melo Farias Moreno  3   5 , Luiz Marcelo Ribeiro Tomé  2   3 , Luiz Augusto Pereira  6 , Debora Glenda Lima de La-Roque  7   8 , Ana Maria Bispo de Filippis  9 , Daniel Garkauskas Ramos  10 , Dario Brock Ramalho  11 , Kátia Cristina de Lima Furtado  12 , Gleissy Adriane Lima Borges  12 , Livia Caricio Martins  13 , Livia C V Frutuoso  10 , Ludmila Oliveira Lamounier  2 , Natália Rocha Guimarães  2   3 , Patrícia Miriam Sayuri Sato Barros  14 , Priscila Souza de Almeida  2 , Paulo Eduardo de Souza da Silva  3 , Rodrigo Giesbrecht Pinheiro  10 , Rodrigo Guerino Stabeli  11 , Shirley Moreira da Silva Chagas  12 , Sílvia Helena Sousa Pietra Pedroso  2 , Simone Kashima  7   8 , Solange Gonçalves Penante  12 , Marília Santini de Oliveira  15 , Vinicius Lemes da Silva  6 , Wesley C Van Voorhis  16 , Edward C Holmes  17 , José Lourenço  18 , Felipe Campos de Melo Iani  2 , Alberto Simões Jorge Júnior  1 , Marta Giovanetti  19   20 , Luiz Carlos Junior Alcantara  3
Affiliations

Re-emergence of Yellow Fever Virus in Brazil: Evidence from Forest and peri-urban Settings

Valnete das Graças Dantas Andrade et al. medRxiv. .

Abstract

Yellow Fever virus (YFV) continues to challenge public health systems across the Americas, despite decades of successful control and the availability of a highly effective vaccine. Following major outbreaks between 2016 and 2022, YFV re-emerged in Brazil in 2023, with a confirmed infection in a non-human primate in São Paulo linked to viral strains circulating in the Midwest region. This reintroduction, combined with increased YFV activity reported across the Americas, signals an ongoing risk of viral persistence and geographic expansion. In this study, we investigate recent YFV dynamics in forest and peri-urban settings, integrating genomic evidence with ecological and spatial data to trace transmission pathways and assess the potential for urban re-emergence. Our findings highlight the need for sustained surveillance in both sylvatic and transitional zones, especially amid fluctuating vaccine coverage and environmental changes that may facilitate spillover events.

Keywords: Brazil; Sylvatic transmission; Yellow fever virus (YFV); genomic surveillance; re-emergence.

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Conflict of interest statement

Conflict of Interest: None declared.

Figures

Figure 1.
Figure 1.. Spatiotemporal dynamics and epidemiological trends of yellow fever virus (YFV) circulation in South America from 2023 to 2025.
a) Geographical distribution of confirmed human YFV cases overlaid on a land cover map of South America. Brazil is highlighted with a black border. Red circles indicate reported cases for each respective year (2023, 2024, and 2025); b) Number of confirmed YFV cases reported per year by country (Bolivia, Brazil, Colombia, Guyana, and Peru). A marked increase in total cases is observed in 2025; c) Number of confirmed cases (left) and deaths (right) reported annually by selected Brazilian states. Data highlight rising case numbers in Pará and Minas Gerais, with associated increases in YFV-related mortality.
Figure 2.
Figure 2.. Genomic and epidemiological characterization of YFV cases in Pará and Minas Gerais, Brazil (2023–2025).
a) Map of Brazil indicating the states of Pará (dark blue) and Minas Gerais (gold) under investigation; b) Proportion of YFV genomes by host (human: orange; NHP: green) and ecological classification (urban, rural/peri-urban, rural, peri-urban, forest/remote rural); c) Sampling dates of sequenced genomes by state (PA and MG) and host; d) Age distribution of human cases by state.; e) Time-scaled maximum likelihood phylogeny including genomes generated in this study and publicly available sequences. Tip colors indicate sampling location; tip fill denotes host (human: orange; NHP: green; mosquito: beige). Vertical bars to the right summarize host metadata. All sequences belong to the South American I lineage.
See this image and copyright information in PMC

References

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