Travellers have been cautioned about a disease transmitted by mosquitos that poses a ‘high risk’ in 42 countries. The Travel Health Pro website, supported by the Foreign Office, recently issued a warning regarding the spread of the virus in various regions of Africa, Central and South America, and Trinidad in the Caribbean.
Yellow Fever, a potentially fatal illness caused by a virus spread by mosquitos, can lead to severe hemorrhagic symptoms, including jaundice, yellowing of the skin and eyes, and internal bleeding affecting vital organs such as the liver, kidneys, and heart. The mortality rate is particularly high among individuals with severe cases of the disease.
In South and Central America, yellow fever remains a concern, with a significant rise in cases reported in 2025 compared to the previous year. There were 346 confirmed cases, including 143 deaths, across seven countries in that region. Since the start of 2026, four countries—Bolivia, Colombia, Peru, and Venezuela—have reported a total of 41 confirmed cases, including 18 fatalities.
The Amazon region, traditionally a hotspot for yellow fever, saw a shift in the geographic spread of the disease in recent years, with cases reported in areas like Sao Paulo State in Brazil and Tolima Department in Colombia. The risk of urban outbreaks has increased due to cases related to jungle transmission near urban centers in South America.
Africa continues to witness probable and confirmed cases of yellow fever, with some countries reporting cases despite suboptimal vaccination coverage. The risk of yellow fever transmission remains high in endemic areas of Africa, where the prevalence of the mosquitoes responsible for transmitting the disease is a significant concern, especially in densely populated urban areas.
Symptoms of yellow fever can vary in severity, with an incubation period of three to six days. Initial signs include muscle pain, high temperature, headache, lack of appetite, nausea, and vomiting. In severe cases, patients may experience acute hemorrhagic fever, characterized by bleeding from various parts of the body, jaundice, kidney damage, and organ failure, which can be fatal in a significant percentage of cases.
*Only certain parts of some countries are at risk of yellow fever transmission. Other areas have a low potential for transmission or no risk at all.
Overall, vigilance, vaccination, and mosquito bite prevention remain crucial in combating the spread of yellow fever in high-risk regions.