An epidemiological study of Schistosoma haematobium and S. mansoni infection in thirty-five rural Egyptian villages.

Probability samples of individuals from 35 village communities in the rural Egyptian Nile Valley were examined for the presence of schistosome ova by sedimentation of urine and by the MIFC technique for stools. In all there were 12,933 persons selected of which 11,337 provided specimens for examination from a total population of 66,768 persons divided among three governorates: 37% in North Central Delta, 31% in Upper-Middle Egypt and 32% in the Upper Egypt. After controlling the differences attributed to sampling methods, 30% of the villagers from Kafr El Sheikh, were found positive for S. haematobium and 20% for S. mansoni. The prevalence of schistosomiasis in the Kafr El Sheikh villages was 42%. South of the Nile Delta in the Beni Suef villages, 27% were found positive for S. haematobium and less than 1% positive for S. mansoni. In Aswan, prevalence was associated with the type and location of the village. Prevalence was low (4%) in villages located on high barren ground, but elevated (25%) in a village built within cropped and irrigated land. S. mansoni cases were also in the Aswan villagers; however, local acquisition of this infection was not substantiated. The specific age-sex distributions for both schistosomes species were characteristic with a notable difference in the male-female infection ratio that increased from north to south. The source of domestic water supply and prevalence of infection were consistently associated. These results were compared to past findings in order to provide a frame of reference to aid in the development of future surveillance and investigations.