Brazil: Yellow fever deaths rise in São Paulo
Health officials with the State Health Department of the State of São Paulo have reported 20 yellow fever fatalities in the state since December 2024, through February 2025.
During the same period, 32 yellow fever cases were confirmed throughout the state, a number well above that recorded in the whole of last year, when there were two confirmations and one death.
The disease was reported this year in cities that make up the regions of Bauru, Campinas, Piracicaba and São José dos Campos. In two cases, the location where the disease was contracted is still under investigation. There are also two imported cases, of people who contracted the virus while traveling to Minas Gerais.
Eight out of ten people who were infected by the virus (81% of the total) had not been vaccinated against the yellow fever. Two cases are still under investigation.
Yellow fever virus is transmitted to people primarily through the bite of infected Aedes or Haemagogus species mosquitoes. Mosquitoes acquire the virus by feeding on infected primates (human or non-human) and then can transmit the virus to other primates (human or non-human). People infected with yellow fever virus are infectious to mosquitoes (referred to as being "viremic") shortly before the onset of fever and up to 5 days after onset.
The last cases of urban yellow fever in the country were recorded in 1942. Since then, transmission has only occurred in the wild, where non-human primates (NHPs) are the main hosts and amplifiers of the virus, as well as humans, who are considered accidental hosts.
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The yellow fever vaccine is the main form of prevention and is available free of charge through the Unified Health System (SUS) throughout the year. For those traveling to high-risk areas, the recommendation is that the vaccine be administered at least 10 days before departure, especially for those who have never been vaccinated.
In 2023, vaccination coverage against yellow fever reached 70%, an increase compared to 2022, when the rate was 60.7%.