Malaria is a disease caused by parasites that are carried by mosquitoes. Once in the bloodstream, the parasite inhabits the red blood cell (RBC. This picture shows purple-stained malaria parasites inside red blood cells. Update Date: 06/20/2007Arnold L. Lentnek, MD, Division of Infectious Disease, Kennestone Hospital, Marietta, GA. Review provided by VeriMed Healthcare Network.