Computer illustration showing different stages of release of malaria merozoites from a red blood cell. Malaria is caused by Plasmodium sp. parasitic protozoans transmitted by female Anopheles sp. mosquitos. When the mosquito bites a person, sporozoites in the mosquito's saliva enter the bloodstream and migrate to the liver, where they infect the cells and multiply into merozoites, which rupture the liver cells and escape back into the bloodstream. The merozoites then infect red blood cells, where they reproduce asexually, periodically breaking out of their hosts (shown here) to invade fresh red blood cells. Sexual forms called gametocytes are also produced, which, if taken up by a mosquito, will infect the insect and continue the life-cycle.