Coloured scanning electron micrograph (SEM) of an Anopheles mosquito midgut infected with Plasmodium vivax oocysts. Seen here are the foregut, midgut and Malpighian tubules. There are approximately 400 species of the Anopheles mosquito, 30 to 40 transmit four different species of the protozoan parasite, Plasmodium, that causes malaria. Malaria is one of the most common infectious diseases and an enormous public-health problem. 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 anaemia, as well as fever, chills, nausea, flu-like illness, coma and death. Magnification: x14 when shortest axis printed at 25 millimetres.