The epidemiology of infection with Entamoeba histolytica in the Gambia, West Africa.

A country-wide stool survey of The Gambia showed the prevalence of Entamoeba histolytica cysts to range from 13.7% up-country in the dry season to 52.3% near the coast. A longitudinal survey showed a near 100% infection rate over one year and a sharp rise in prevalence as the rains commence with an equally sharp fall as the rains progress. Specific antibody levels are elevated and reasonably constant through the year. Carriers generally show no specific lymphocyte reactivity to amoebic antigen but consistently parasite-negative individuals tended to show elevated lymphocyte reactivity. Attempts to discover the presence of cysts in the environment of villages by cultivation of specimens of water, soil, food, flies and washing from clothes and hands generally failed though E. histolytica was recovered once from a well.