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Abstract : |
Experimental infections of preadult and adult Lymnaea cailliaudi snails using the same isolates of Fasciola gigantica miracidia were performed under laboratory conditions to determine whether the temperature, intensity of infection and age of snail host of F. gigantica in Egypt had an effect on the dynamics of metacercarial productivity. Preadult snails were divided into 3 groups kept at 18-20, 24-26 and 29-31C, respectively and the adult snails were represented by a single group kept at 24-26C to compared to its corresponding preadults ones. Each group was divided into four subgroups a, b, c and d, each one was subjected to 1, 2, 3 and 5 miracidial exposures, respectively. Two miracidial infections per snail produced more metacercariae compared to that of 1, 3 or 5 miracidial infections. Prepatent period of F. gigantica inside its snail host was inversely related to temperature and markedly affected by age rather than the number of miracidia inoculated. In contrary, Patent periods were significantly affected by the intensity of miracidial infection. Temperature above 24C was suitable for high metacercarial production and a significant increasing in the percentage of the floating metacercariae was found at high temperature. Adult snails showed less susceptibility to infection as they never infected with single miracidia and produced few metacercariae with more than single miracidial infection., |
