Background: Heterophyiasis is an intestinal sickness promoted by infection with the heterophyid digenetic worms. It is one of the major infectious diseases of public health in the developing countries. Method: Single-cell gel eletrophoresis, or comet assay, was carried out for detecting DNA damage in the digestive gland cells of Pirenella conica infected with Heterophyes larvae. Besides, apoptosis, some isoenzymes, and two biogenic amines (neurotransmitters) were investigated using the flow cytometric analysis, the starch gel electrophoresis, and the HPLC techniques respectively. Snails were collected from brackish water area around Port Said province during the spring-summer periods of 2012-2013. Results:The results showed that infection with the larval trematodes increased tail length (length of DNA migration) in the digestive gland cells of infected snails. Meanwhile, the percentage of apoptosis was significantly elevated (58.80%) in the snails infected with the larval trematodes as compared to that of uninfected snails (39. 59%). Apparent polymorphism was detected in the four enzymes obtained from the digestive gland extracts.