Malaria is a serious disease caused by a microscopic parasite that infects red blood cells.
The severity of disease depends on the species of Plasmodium causing the infection and the immune status of the person infected. Any person can get malaria if they are bitten by an infected mosquito in a region where malaria occurs. Almost all cases in the U.S. are acquired during travel to countries where malaria occurs. The malaria parasite is carried by infected humans in their bloodstream. When a mosquito ingests blood from an infected person, the malaria parasite develops into an infective stage within the mosquito and later is injected into another person when that infected mosquito feeds again.