The US Centers for Disease Control and Prevention (CDC) has issued a travel warning for South America due to a rise in yellow fever cases and spread to new areas. Travelers to Bolivia, Colombia, Peru, except Chile and most of Argentina, are advised to get vaccinated at least 10 days before leaving the US. Those who received their last booster dose over 10 years ago may need a second dose.
According to the Pan American Health Organization (PAHO), there has been high yellow fever activity in South America in the first quarter of 2025, with 131 human cases confirmed and 53 deaths reported. In contrast, only 61 cases were reported in all of 2024, resulting in 30 fatalities.
Yellow fever is spread by mosquitoes, and the CDC advises travelers to take precautions against bites. If infected, people may develop severe illness that can lead to serious complications such as liver disease, bleeding, and death. The risk is higher for those who have not been vaccinated or have not had a booster dose in over 10 years.
Source: https://www.cidrap.umn.edu/yellow-fever/cdc-issues-level-2-travel-notice-yellow-fever-south-america