ULTRASONOGRAPHICAL ASSESSMENT OF MORBIDITY IN SCHISTOSOMIASIS-MANSONIIN MADAGASCAR - A COMMUNITY-BASED STUDY IN A RURAL-POPULATION

Between June and November 1993, a parasitological, clinical and ultras onographical survey was carried out in the mid west of Madagascar, amo ng the whole population of a village where Schistosoma mansoni was end emic. S. mansoni eggs were found in the stools of 61.8% of the 544 ind ividuals examined; the highest prevalence of infection (85.7%) was obs erved in the 15-19 years old age group. The most intense infections we re 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 excret ed more than 400 eggs/g. The egg count decreased steadily from the age of 15 years. Ultrasonographical examination was performed in 482 inha bitants older than 2 years: 29% of them presented definite schistosome associated river alterations according to the proposals for staging S . mansoni infection made by the World Health Organization Cairo workin g group. Stage 3 was never observed in subjects under 30 years old. Th is is consistent with the need for a long-standing infection before se rious lesions occur. A significant relationship between egg count and degree of liver alterations was found only in the 20-29 years age grou p.