Coloured scanning electron micrograph (SEM) of Plasmodium vivax oocysts in a Mosquito (Anopheles sp.) midgut. Anopheles is a genus of mosquito from the family Culicidae. There are approximately 400 species of the Anopheles mosquito, 30 to 40 transmit four different species of the parasite, Plasmodium, that causes malaria. Malaria is one of the most common infectious diseases and an enormous public-health problem. The disease is caused by protozoan parasites of the genus Plasmodium. The most serious forms of the disease are caused by P. falciparum and P. vivax. Malaria is a vector-borne infectious disease that is widespread in tropical and subtropical regions. It causes disease in approximately 400 million people every year and is the cause of between one and three million deaths annually, mostly among young children in Sub-Saharan Africa. The parasites, transmitted by the female mosquito when she sucks blood, multiply within red blood cells, causing symptoms that include symptoms of