From the end of December 2024 to April 26 of this year, five countries in the Americas confirmed 212 yellow fever cases and 85 related deaths, for a case-fatality rate of 40%, the World Health Organization (WHO) said in any update today.
Those numbers represent a more than tripling of cases of the mosquito-borne disease recorded for all of 2024, the agency said.
Most cases, deaths in Brazil
The 212 cases were confirmed from December 29, 2024, through April 26, 2025, with data for Ecuador analyzed through May 2. Brazil has the most cases and deaths—110 and 44, respectively. Colombia has 60 cases and 24 deaths, Peru 35 cases and 12 deaths, Ecuador 4 fatal cases, and Bolivia, 3 infections, including 1 fatal case.
“In 2024, human cases of yellow fever were reported mainly across the Amazon region of Bolivia, Brazil, Colombia, Guyana, and Peru,” the WHO said. “In 2025, however, cases have been detected mainly in areas outside the Amazon region, including in the state of São Paulo, Brazil and the Tolima department, Colombia.” Last year, the Americas region had 61 confirmed yellow fever illnesses.
The five affected countries have implemented actions to respond to the outbreaks, focusing on strengthening preventive measures, improving surveillance, and implementing immunization campaigns.Â
The WHO determined that the risk of yellow fever spread in the region is high. “The occurrence of yellow fever cases outside of the Amazon basin, combined with high fatality, varying vaccination coverage across affected countries, and limited vaccine supply, contributes to the overall classification of yellow fever risk in the Region of the Americas, especially in endemic countries, as high,” the agency said.Â
“WHO emphasizes the importance of active surveillance, timely laboratory testing, cross-border coordination, and information sharing. Vaccination remains the primary means for the prevention and control of yellow fever.”
