Many diseases are caused by protists. Some familiar ones from various regions around the world are: Entamoeba histolytica, a parasitic amoeba which causes amoebic dysentery, an intestinal disorder. It’s estimated that up to ten million individuals in the United States have parasitic amoebas, but only two million exhibit symptoms of the disease. In tropical areas, up to half the population may be infected. Species of Trypanosoma (called trypanosomes) are the cause of the “African sleeping sickness” (both T. gambiense and T. Rhodesiense, transmitted by biting flies of the genus Glossina, or tsetse fly); and from the American tropics, Chagas’s disease (caused by T. cruzi, spread by blood-sucking bugs of the genera Triatoma and Rhodnius). And the protist Plasmodium causes malaria, in which an individual of the genus Plasmodium enters the human body through a bite of a mosquito of the genus Anopheles that has been infected by the protist. (For more diseases and other effects of protists, see below.)