WHO Issues Emergency Over Rapid Mpox Spread
Yellow fever cases are climbing fast across South America, and the death toll continues to rise. The World Health Organization urges affected countries to take action before the outbreak worsens.
Infections and Deaths Climb Across Five Countries
Between December 2024 and April 2025, officials in Brazil, Colombia, Peru, Ecuador, and Bolivia confirmed 212 cases and 85 deaths. That's almost three times more than during the same period last year.
Brazil has the highest case count, with significant outbreaks also emerging in Colombia.
The concerning dissimilarity this year lies within the geographic shift. In past years, cases were mostly limited to remote areas near the Amazon River. This time, infections are emerging in cities and towns beyond the river, in areas with larger, more mobile populations.
Mosquitoes Are Reaching New Territory
Yellow fever spreads through mosquito bites— mainly Aedes aegypti, the same species known for carrying dengue and Zika. Thanks to warmer temperatures and longer rainy seasons, these infected mosquitoes can spread to places they typically are not accustomed to.
Scientists attribute climate change. They state that it's creating ideal conditions for mosquito-borne diseases to spread farther and faster, turning a once-contained virus into a broader threat.
Vaccine Access Falls Short
Yellow fever is one of the few deadly viruses for which a proven vaccine exists, offering lifelong protection. And yet, large portions of the population remain unvaccinated either due to lack of access, misinformation, or limited public health infrastructure.
In response to the recent outbreak, Colombia launched a mass vaccination campaign in high-risk zones. Brazil and other countries are also stepping up their efforts, attempting to close the gap before more people fall ill.
Travel Warnings and Basic Precautions
The U.S. Centers for Disease Control and Prevention has issued a Level 2 travel advisory for parts of South America. Travelers are urged to get vaccinated at least 10 days before departure and to take steps to avoid mosquito bites— especially during the early morning and late afternoon when the insects are most active.
There are currently no formal travel restrictions in place, but health officials are closely monitoring the situation.
WHO Calls for Stronger Surveillance
WHO is also pushing for better disease tracking, more testing, and improved communication between countries.
Vaccination is the strongest line of defense, but identifying new cases quickly and sharing that information across borders is equally vital in slowing the spread.
It's Not Just About Mosquitoes
The five countries hit hardest are all low- or middle-income nations. Areas already dealing with limited healthcare resources, economic instability, and the effects of climate change.
Public health experts warn the recent yellow fever outbreaks are a small part of a much bigger picture. To avoid repeat scenarios, investing solely in vaccinations may not make a significant difference. However, investing in infrastructure, climate resilience, and basic health systems, especially in high-risk zones, will have the greatest long-term impact.
Bottom Line
Yellow fever has been around for centuries, but this outbreak is different. The virus is spreading faster, reaching farther, and exposing serious cracks in our global health defenses.
The WHO is urging countries to act now through vaccination, surveillance, and international coordination before this situation becomes much harder to contain.