Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Zoology

Many snails act as intermediate hosts of medically and veterinary important trematodesthat infect humans or life stock animals.Four types of cercariae were found, Xiphidiocercarie, Furcocercous, Pleurolophocercous and Gymnocephalous among the four species of snails (Melanoidestuberculata, Bulinustruncatus, Biomphalariaalexandrina and Lymnaeanatalensis) .The data on DNA strand breakage, expressed as the mean tail DNA content and the mean tail length in hemocytes of M. tuberculata, L.natalensis, B. truncatus and B. alexandrina exposed to parasite infection was studied.Considering the four different classes of DNA damage, a highly significant difference among different snail groups was observed. A strong dose{u2013} response relationship was observed for the classes 0 and 3.Snails were individually collected, assayed by the PCR, and showed negative, while DNA extract from individual infected snails was examined different number of bands of amplification ladder bands seems to be related to the tested parasite concentration.Identification of infected snails when its DNA is pooled with DNA aliquots from several uninfected snails should increase the feasibility of using PCR assay for mass screening of infection. This is expected to be possible only when the detection sensitivity is very high

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