After the mysterious deaths of three monkeys of different species in Putumayo, Colombia, health teams quickly determined the cause. They identified that the deaths were not random or coincidental, but the beginning of what could have been a yellow fever outbreak in Colombia. It is a highly contagious virus mainly transmitted by mosquito bites.

However, it can be prevented by vaccines, which are relatively affordable and easily accessible. Nonetheless, depending on the region, it can be harder to access or afford. In 2025, five countries reported an increasing presence of yellow fever. In Colombia (as of June 28, 2025), there have been 114 confirmed human yellow fever cases, 49 confirmed deaths and case fatality rate of 43%.

The Pan-American Health Organization (PAHO) offered training to health teams through the PROTECT initiative in Colombia. It educated health workers on taking preventative measures quickly and efficiently against outbreaks of viral diseases such as yellow fever.

Education From Health Professionals

Following the deaths of the monkeys, several immediate preventative measures were taken. These included vaccinating environmental workers, conducting entomological studies and analyzing the affected area. Due to the training offered by PAHO, health teams were taught how to take samples from wildlife safely and the importance of integrated surveillance.

Integrated surveillance showed health workers the importance of monitoring primates and mosquitoes in the area and shared many tools to take preventative action and control outbreaks. Due to strong surveillance of the area, Colombian professionals were able to identify the presence of yellow fever in Putumayo, Colombia and control further spread of the virus.

Maintaining high vaccination levels and continued wildlife surveillance will help catch future outbreaks before they become too severe. Colombia has issued regulations and laws to help contain the spread of yellow fever and increase preparedness for future situations where swift action is needed.

PAHO has urged countries to “maintain active surveillance, vaccinate at-risk populations and ensure rapid responses to early warning signs — such as unexplained monkey deaths.” This is extremely important because our health depends on the health of our environment and the wildlife inside it. Monkeys are extremely similar to humans, so we won’t be far behind if they are affected.

The Future of PAHO’s Health Initiative

PAHO has made guidance documents publicly available on the regional level, which include instructions on safe sample collection, guidelines for managing control endeavors and maps of high-risk areas. It continues to conduct in-person training on surveillance and entomology of yellow fever for vulnerable countries.

Colombia has also issued circulars that establish transitional measures for yellow fever vaccinations. The criteria of these letters extend from ages 9 months to 59 years of age. The public health risk of yellow fever is extremely high.

However, with these measures implemented by PAHO/WHO, such as increasing vaccination levels, people have been successfully learning to save lives and contain outbreaks of yellow fever in Colombia.

– Bowie Aldrich

Bowie is based in North Syracuse, NY, USA and focuses on Business and Global Health for The Borgen Project.

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