Yellow fever is a tropical virus infection that mostly occurs in Africa. It can, however, also occur in parts of Central and South America, which is why you would have been advised to have the vaccination.

Mosquitoes transmit the virus to humans when they bite. It's known as yellow fever because it can cause the skin and the whites of the eyes to turn yellow, called jaundice. The fever appears three to six days after being bitten and is sometimes accompanied by other flu-like symptoms such as muscle aches and fatigue. The illness may also cause kidney and liver failure, abnormal bleeding and, when severe, convulsions and coma.

The collection of symptoms and a blood test help doctors to confirm the diagnosis of yellow fever, for which there's no specific treatment. Although most people recover from the infection it can be fatal, which is why those travelling to high-risk areas of the world are advised to have the vaccination. Fewer travellers become infected with yellow fever nowadays because of the very good protection that vaccination provides against it. This protection lasts for about ten years. It's still essential to try and avoid being bitten by the mosquitoes by using repellents and covering the skin with appropriate clothing.