Brazil's Yellow Fever Detections Increased in 2023

A recent article published by the journal Science Direct highlights the importance of responses to public health emergencies, such as the increasing number of yellow fever (YF) cases in the Federative Republic of Brazil.

In a March 2024 article, researchers compared the detection and phylogenetic analysis of the YF virus in two neotropical primates (monkey), a Callithrix detected in the previous epidemic period (2016–2020) and a Callicebus nigrifons, which showed a new introduction of YF virus in Brazil during 2023.

In 2022, the Pan American Health Organization confirmed Brazil reported four deaths related to yellow fever infections.

Mosquitoes that transmit the yellow fever virus can be found throughout the Amazon and along most river basins in Brazil.

Evidence of an expanded range of yellow fever transmission in Brazil led the WHO and the U.S. CDC to broaden their vaccination coverage recommendations in 2017.

Since Brazil is a favorite destination for millions of international travelers, the U.S. CDC says travelers to Brazil should be updated on routine vaccines, including the YF vaccine.

YF vaccination is recommended for most travelers going to the states of Acre, Amapá, Amazonas, Distrito Federal (including the capital city, Brasília), Espírito Santo, Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Pará, Paraná, Piauí, Rio de Janeiro (including the city of Rio de Janeiro and all coastal islands), Rio Grande do Sul,* Rondônia, Roraima, Santa Catarina, São Paulo (including the city of São Paulo and all coastal islands), Tocantins, and designated areas of Bahia.

The CDC's expanded YF vaccination recommendations for these states are preliminary. For updates, refer to the CDC Travelers' Health website.

"Even if your travel plans to Brazil are limited to popular urban areas like São Paulo or Rio de Janeiro, you are still at risk for yellow fever infection because the mosquito variety that carries the yellow fever virus has adapted to live in cities and bites during the day time," says Jeri Beales MSN RN, with Destination Health, located near Boston, MA.

"The good news is the yellow fever vaccine is very effective at preventing infections, and it protects for at least ten years, with some people only needing a single lifetime dose," added Beales.

Although Brazil does not require proof of vaccination against yellow fever for entry into the country, people planning to travel to other countries in South America (e.g., Colombia) could be required to show proof of yellow fever vaccination before exiting Brazil.

As of January 16, 2024, several yellow fever vaccines have been authorized by various countries. In the U.S., the YF-VAX® vaccine is available at travel clinics.