Ultrasonographical assessment of morbidity in schistosomiasis mansoni in Madagascar: a community-based study in a rural population

Abstract

Between June and November 1993, a parasitological, clinical and ultrasonographical survey was carried out in the mid west of Madagascar, among the whole population of a village where Schistosoma mansoni was endemic. S. mansoni eggs were found in the stools of 61·8% of the 544 individuals examined; the highest prevalence of infection (85·7%) was observed in the 15–19 years old age group. The most intense infections were recorded in the 10–14 years age group, in which the geometric mean egg count was 265 eggs/g of faeces and 34·3% of the individuals excreted more than 400 eggs/g. The egg count decreased steadily from the age of 15 years. Ultrasonographical examination was performed in 482 inhabitants older than 2 years: 29% of them presented definite schistosome associated liver alterations according to the proposals for staging S. mansoni infection made by the World Health Organization Cairo working group. Stage 3 was never observed in subjects under 30 years old. This is consistent with the need for a long-standing infection before serious lesions occur. A significant relationship between egg count and degree of liver alterations was found only in the 20–29 years age group.