Malarial blood cell. Coloured scanning electron micrograph (SEM) of an erythrocyte (red blood cell) infected with Plasmodium parasites, the cause of malaria. The parasite is transmitted to the blood by the bite of female mosquitoes. The parasites replicating within the cells and destroy them upon release. This can cause anaemia. The parasites may then reinvade more red blood cells, causing the severe cyclic fevers of malaria.