Lipids in the host-parasite system: Digestive gland of Lymnaea truncatula infected with the developmental stages of Fasciola hepatica

Effects of the presence of sporocysts, rediae and cercariae of Fasciola hepatica on the lipid content in the digestive gland of Lymnaea truncatula as well as on lipid levels in tissues of the parasites themselves were studied. Lipids were examined by means of histochemical and cytophotometric techniques. The snail's digestive gland lipid level was found to be almost halved in 20 days post infection; a more then 80% reduction being visible after the subsequent 40 and 60 days. The loss of lipids in the digestive gland of the infected snails point at mobilisation of lipid energy reserves to compensate for the deficiency of carbohydrates, used by these parasites. The parasite tissues such as tegument, pharynx, suckers and germ balls showed considerable lipid contents and were metabolically active. It supports the hypothesis that lipids are used as energy source by developmental stages of this parasite.