Prepotency of schistosoma haematobium in snails at different constant temperatures

The developmental time of Schistosoma haematobium in Bulinus truncatus was determined at different constant temperatures between 18°C and 32°C. The basic relationship between the length of the minimum prepatent period [Y, in days] and the temperature [X, in°C] is given by the hyperbolic formula Y = 295 / [X-15.3], 15.3 being the theoretical [developmental null point] and 295 the constant time-temperature product. The epidemiological application, the prognosis of the transmission period and the estimation of the transmission potential in relation to climatic conditions are discussed