Evaluation of the effect of larval metamorphosis of some digenetic parasites within the digestive gland tissues of the freshwater ampullariid snails, Lanistes carinatus (Olivier, 1804)

Ampullariid snail, Lanistes carinatus, was infected with larval stages of the two digenean parasites, one of which belonged to the genus Echinochasmus, and the other belonged to the genus Phaneropsolus. The first genus has gymnocephalus cercariae type, while the other has xiphidicercariae type. The later cercariae characterized with presence of xiphoid spine at oral sucker, while the first one has spines on its oral sucker. When examining the digestive gland of snails, it is the presence of growth and metamorphosis for both parasites. The histological study of the digestive gland infected with the larval stages showed that the larval development of Echinochasmus parasites progresses from sporocyst to mother sporocyst to the redia before it turns into gymnocephalus cercariae. As for the larval development of the genus Phaneropsolus, it appears to have undergone the larval transformation from the sporocyst stage only before reaching the cercaria stage of the type xiphidiocercaria. The histopathological study of the tissues of the affected digestive glands showed that the effect of the presence of the larval stages was severe and destructive to the cells of the glands. It appears from the observation that mechanical and physiological activity of the larvae was the cause of a major change in the normal structure of tissue of the affected glands. Therefore, the present study traces the pathological effect caused by any parasite within the tissues of any host, is noted, but a fingerprint specific to it that can be taken as evidence of its presence and no other.