Relationship between pure Schistosoma haematobium infection in Upper Egypt and irrigation systems. Part II: Host characteristics. The general prevalence of Schistosoma haematobium, age and sex distribution

The epidemiology of bilharziasis was studied in 4 villages in Upper Egypt. A definite relationship between the prevalence of S. haematobium infection and the type of irrigation system was further noted. A low prevalence was found in Gezirat El Maabda (2.95%). In the other 3 villages a much higher prevalence existed (31.9%, 46.2% and 38.9% in Nazza Karar, El Ghorayeb and Garf Sarhan, resp.). The higher prevalence of S. haematobium in Nazza Karar (31.9%) only 3 years after introduction of perennial irrigation was a disappointing finding. It forms evidence against the elaborate measures and precautions planned and incompletely implemented before or after the establishment of the Aswan High Dam. Not a single case of S. mansoni was encountered during this study. As regards the age and sex distribution of S. haematobium in the 3 villages irrigated perennially, a steep rise began in the 5-9 years age group reaching a peak at the 10-14 years age group. In Gezirat El Maabda the peak was reached at a later age (15-19 years). The cause of this difference is explained. Males showed a higher rate of infection than females in almost all age groups of the 4 villages studied.