An annoying, itchy bump may not be the only thing a mosquito leaves behind after a bite. Mosquitoes can spread diseases, too. Viruses like West Nile and chikungunya may make you feel pretty bad for a time, but they aren't life-threatening. While malaria and yellow fever can be more serious, they aren't common in the U.S.
Fortunately, when you protect yourself from mosquito bites, you prevent the sickness as well as the scratching.
Female mosquitoes need protein to lay their eggs. They get it by feeding on warm-blooded creatures, including birds, horses, and people. When a mosquito bites an infected animal (or a person, in some cases) and then bites you, it can pass the disease to your blood through its saliva.
Almost all mosquito-bite illnesses have similar symptoms:
Sometimes they're mistaken for the flu. Most mild cases will go away with rest and time.
There are vaccines and medicines that can lessen your chance of getting some of these illnesses, even if you're bitten.
West Nile Virus
Most people who get West Nile virus don't have any symptoms. About 1 in 5 will have a fever and other flu-like symptoms. Feeling worn out could take months to go away completely. A few people get a more serious infection that causes brain swelling, or meningitis. There's a very small chance you could die.
People in 48 of the 50 U.S. states, Africa, Europe, the Middle East, and West and Central Asia have had West Nile.