Geographic distribution of schistosomes that infect humans differs by species: S haematobium: Widely distributed over the African continent with smaller foci in the Middle East, Turkey, and India S mansoni: Widespread in Africa, foci in Middle East, and the only species in the Western Hemisphere in parts of South America and some Caribbean islands S japonicum: Asia, mainly in China, the Philippines, Thailand, and Indonesia S mekongi: Southeast Asia S intercalatum: Central and West Africa Humans are the main reservoir of infection.