Epidemiology and control of echinococcosis in sub-Saharan Africa.

Cystic echinococcosis (CE) is highly endemic among the nomadic pastoral tribes of East Africa, but is rare amongst the agriculturally based communities. Echinococcus granulosus infections are common in dogs from all countries in sub-Saharan Africa where they have been examined. Transmission of E. granulosus to humans is affected by such factors as prevalence of the parasite in domestic dogs, behaviors of humans towards dogs, and heterogenicity of the parasite and susceptibility of humans to infection. Sheep and goats appear to be the most common domestic intermediate hosts, but recent studies suggest that camels are equally important intermediate host, especially in Sudan and Turkana. At least five of ten E. granulosus genotypes are infective to humans in sub-Saharan African. Most human cases of CE are caused by the sheep strain (GI) and camel strain (G6) of E. granulosus. Other strains occurring in the area may include a lion strain, the horse strain (G4 or Echinococcus equinus) and the cattle strain (G5 or Echinococcus ortleppi).