Yellow Fever outbreak in Colombia

Colombia has been a hotspot of yellow fever cases in 2025. An official government report (Jan 11, 2026) records the death of a 17-year-old boy in the city of Ibague. However, it also states he was referred from the Tolima municipality. Tolima has been the epicentre of a large outbreak in 2025 with forty-seven deaths recorded over the past year. Tolima is also a forested region which is favourable to the transmission of the virus from non-human primates to people.

Yellow fever vaccination rates have also been low.

The first cases in the current outbreak started in October 2024.

What is Yellow Fever and how is it transmitted?

Yellow fever is a serious viral disease. The virus belongs to the Flavivirus genus (the same group containing Japanese encephalitis, dengue fever, Murray valley encephalitis, and others). The disease is transmitted to humans via a mosquito bite.

Yellow Fever is found in tropical and subtropical areas of Africa and South America. The name, “yellow”, comes from jaundice due to the hepatitis observed in severe disease.

Most cases of yellow fever are self-limited but the mortality rate in severe disease can be as high as 50%. There is no specific antiviral therapy. Treatment can only be supportive.

Transmission from person to person is possible during the viraemic phase of the disease. This is the main reason for it being subject to international health regulations. It is possible for an infected person to initiate an outbreak after international travel, but this is only possible if the receptive mosquito is present in the area.

For international travellers, the yellow fever vaccination may be required by law in some circumstances. It is important to have a travel medicine consultation if considering travel to/from endemic areas.

Yellow fever risk to travellers.

Yellow fever vaccination - effectiveness and long term protection