Yellow fever is caused by a virus
carried by mosquitoes. It's
usually found only in tropical parts of Africa and South America. Most people who
are bitten by an infected mosquito don't get sick. People who do might have a fever
or headache, throw up, and get jaundice,
which turns the skin yellow and gives the fever its name.
Most people with yellow fever get better with no problems. There is a vaccine to
prevent yellow fever if you are travelling to places where the disease is common.