Infection of two lymnaeid snails with Fasciola gigantica in Giza, a field study.

Population density of Lymnaea natalensis and L. columella and their natural infection with Fasciola gigantica were followed in two water bodies in Abu Rawash area, Giza Governorate over two years. L. natalensis snails were more abundant during December-February, while L. columella snails had high density during autumn. According to the snail size, we found that the reproduction of the two vector snails occurred in summer and early autumn. Fasciola was present in 0.6 and 2.0% of the examined L. natalensis and L. columella snails respectively. A high prevalence of F. gigantica in L. columella snails occurred in summer and early autumn, while their presence in L. natalensis was irregular. Naturally infected Lymnaea snails, with Fasciola, are usually of large size (> 10mm) of a given population sample. Other three types of trematode cercariae were found in both snail species; Xiphidiocercariae, Echinostomes and Amphistomes.