The effect of peritrich ciliates on some freshwater leeches from Assiut, Egypt

During October 2004 to April 2005, when water temperature ranged between 18 and 22 degrees C, over than 500 specimens of leeches namely Alboglossiphonia polypompholyx, Batracobdelloides tricarinata, Helobdella conifera (Rhynchobdellida), Barbronia assiuti, and Salifa delicata (Arhynchobdellida) were collected from Al-Sont canal near Assiut city. About 80% of these specimens were infected with the peritrich ciliate Epistylis sp. The infection occurred in the field, both rhynchobdellid and arhynchobdellid leeches were infected, but Epistylis can infect rhynchobdellids more than arhynchobdellids. Both light and scanning electron microscopy showed the morphology of this parasite which attached to the surface of the leech body by a stalk. Histopathological studies revealed the damage of cuticle, epidermis, and dermis of the leech body wall at the area of attachment and the leech body seemed to be sloughy. Presence of this parasite in high numbers covering large areas of the body can impede gas exchange leading to leech suffocation and finally its death. Like the other sessile single-celled ciliates Epistylis spp. feed on bacteria and suspended organic debris, which are prevalent in nutrient-rich water, hence, Epistylis is a good indicator of poor water quality (pollution). The present study represents the first report of the effect of Epistylis on leeches collected from Egypt.