First report of Posthodiplostomum minimum metacercariae and resulting histopathological changes in Bagrus bajad from Lake Nasser, Egypt.

Parasitological studies of 100 Bagrus bajad fish were collected from Lake Nasser, Aswan, Egypt. Out of them 75 were infected with metacercariae in two forms; encysted in most visceral organs and free only in air bladder. These were identified morphologically as Posthodiplostomum minimum metacercariae (Strigeidida: Diplostomidae). The intensity of white grub in B. bajad was high in the intestine (30 encysted metacercariae/g). The highest prevalence season observed in summer and the lowest in winter. The histopathological examination revealed encysted metacercariae of different sizes within the intestinal musculature accompanied with granular infiltration with eosinophilia. Degenerative changes were observed in liver and kidney cells, as well as congestion of hepatic sinusoids. Spleen showed both lymphoid and melanomacrophages cells depletion.