Sub-Saharan Africa This section includes general information about health hazards as reported by the World Health Organization and the U.S. Centers for Disease Control and Prevention. The region includes Angola, Benin, Burkina Faso, Burundi, Cameroon, Cape Verde, Central African Republic, Chad, Comoros, Congo, Cote d'Ivoire, Democratic Republic of the Congo, Djibouti, Equatorial Guinea, Eritrea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Madagascar, Malawi, Mali, Mauritania, Mauritius, Mozambique, Niger, Nigeria, Reunion, Rwanda, Sao Tome and Principe, Senegal, Seychelles, Sierra Leone, Somalia, Sudan, Togo, Uganda, United Republic of Tanzania, Zambia, and Zimbabwe. In this area, entirely within the tropics, the vegetation varies from the tropical rain forests of the west and center to the wooded steppes of the east, and from the desert of the north through the Sahel and Sudan savannas to the moist orchard savanna and woodlands north and south of the equator. Many of the diseases listed below occur in localized rural foci and are confined to rural areas. Arthropod-borne diseases are a major cause of disease. Malaria in the severe falciparum form occurs throughout the area, except at over 2,600 meters altitude and on the islands of Reunion and Seychelles. Various forms of filariasis are widespread; endemic foci of onchocerciasis (river blindness) exist in all the countries listed except in the greater part of Kenya and in Djibouti, Gambia, Mauritania, Mozambique, Somalia, Zambia, Zimbabwe, and the island countries of the Atlantic and Indian Oceans. However, onchocerciasis exists in the island of Bioko, Equatorial Guinea. Both cutaneous and visceral leishmaniasis may be found, particularly in the drier areas. Visceral leishmaniasis is epidemic in eastern and southern Sudan. Human trypanosomiasis (sleeping sickness), mainly in small isolated foci, is reported from all countries except Djibouti, Eritrea, Gambia, Mauritania, Niger, Somalia, and the island countries of the Atlantic and Indian Oceans. In Angola and the Democratic Republic of the Congo, the transmission of human trypanosomiasis is very high, and there is significant risk of infection for travelers visiting or working in rural areas. Transmission rates are also high in Sudan and Uganda. Relapsing fever and louse-, flea-, and tick-borne typhus occur. Natural foci of plague have been reported from Angola, the Democratic Republic of the Congo, Kenya, Madagascar, Mozambique, Uganda, the United Republic of Tanzania, and Zimbabwe. Tungiasis is widespread. Many viral diseases, some presenting as severe hemorrhagic fevers, are transmitted by mosquitos, ticks, sandflies, etc., which are found throughout this region. Large outbreaks of yellow fever occur periodically in the unvaccinated population. Foodborne and waterborne diseases are highly endemic. Schistosomiasis (bilharziasis) is present throughout the area except in Cape Verde, Comoros, Djibouti, Reunion, and the Seychelles. Alimentary helminthic infections, the dysenteries and diarrheal diseases, including giardiasis, typhoid fever, and hepatitis A and E are widespread. Cholera is actively transmitted in many countries in this area. Dracunculiasis (Guinea-worm) infection occurs in isolated foci. Paragonimiasis (oriental long fluke) has been reported from Cameroon, Gabon, Liberia, and most recently from Equatorial Guinea. Echinococcosis (hydatid disease) is widespread in animal-breeding areas. Hepatitis B is hyperendemic. Poliomyelitis (also a food-borne and water-borne disease) is endemic in most countries except Cape Verde, Comoros, Mauritius, Reunion, and the Seychelles. Trachoma is widespread. Among other diseases, certain, frequently fatal, arenavirus hemorrhagic fevers have attained notoriety. Lassa fever has a virus reservoir in a commonly found rat. Studies have shown that an appreciable reservoir exists in some rural areas of West Africa; people visiting these areas should take particular care to avoid rat-contaminated food or food containers, but the extent of the disease should not be exaggerated. The Ebola and Marburg hemorrhagic fevers are present but reported only infrequently. Epidemics of meningococcal meningitis may occur throughout tropical Africa, particularly in the savanna areas during the dry season. Other hazards include rabies and snake bites.