Schistosomiasis, intestinal
Epidemiology
- S. mansoni is endemic in Africa (including Madagascar), the Arabian peninsula and parts of South America
- S. japonicum is distributed in China, Taiwan, the Philippines and Sulawesi (Celebes)
- S. mekongi occurs in the Mekong River area of Laos, Cambodia and Thailand
- Humans become infected when they have contact (during bathing, washing, fishing) with freshwater into which snails have shed cercariae
- Schoolchildren have the highest worm burden in endemic areas. A partial immunity (“concomitant immunity”) protects adults from reinfection
- Building of dams and irrigation system favours habitats for the intermediate host snail