RESUMEN
A comparative study of the shell structure, seasonal temperature and Calcium content of Bulinus snails from two areas [Damietta and Giza] in Egypt was done and compared with laboratory snails from Schistosome Biological Supply Center [SBSC]. The shells of collected snails identified as Bulinus truncatus, showed a wide variation in shape. The results showed a significant differences were detected between the populations from SBSC and Damietta [p<0.05] for mean of measured shell width, aperture length, length of spire and number of whorls. The populations from Giza and Damietta governorates showed significant differences [P<0.05] in mean of measured length of diagonal, length of body whorl above aperture, length of spire and number of whorls. There were no statically significant differences between the populations from SBSC and Giza. The seasonal temperature affected on susceptibility of snails to infection with Schistosoma haematobium. The mean prepatent period was short in summer and long in winter. The shells of S. haematobium - infected B. truncatus snails showed hypocalcification from all localities