Prevalence of Schistosomiasis and dynamics of its distribution in some villages in Qalyoubia Governorate.

A total of 1535 persons of different age, sex and occupation from 5 villages (Tanan, El-Sad, Sandiun, Kalama and Taha-nob) in Qalyoubia Governorate in Nile Delta were subjected to clinical, stool, urine and intradermal tests accompanied by a questionnaire for 500 of them. Snail vectors of Schistosome parasites were collected from 2 villages (El-Sad and Taha-nob) and snail densities in the waterways as well as the prevalence rate of infection with schistosomal cercariae were recorded. The results revealed that the average prevalence rate of Schistosoma haematobium in the 5 cillages was 4.9% (range 2.3% - 7.1%) and that of S. mansoni was 13.3% (range 11.4-14.4%). The overall prevalence of both types was 18.2% (range 13.7-21.4%). The average density of Biomphalaria alexandrina in the 2 village was 16.47% and that of Bulinus truncatus was 7.5%, the ratio was 2:1. The infectivity with schistosomal cercariae was very low with an average of 2.5% in B. Alexandrina and 1.5% in B. truncatus. Factors responsible for the decreased rates of schistosomiasis and snail infectivity were discussed.