Histopathological changes in naturally-infected Chirruh snowtrout, Schizothorax esocinus (Heckel), with Adenoscolex oreini (Caryophyllidea: Capingentidae)

The aim of this study was to carry out histopathological studies on the intestines of Chirruh snowtrout, Schizothorax esocinus (Heckel), naturally infected with the caryophyllidean cestode, Adenoscolex oreini. The specimens of S. esocinus (25-40 cm) were collected from the Jhelum River, Kashmir, India. Heavily infected fish (> 50 worms per individual host) with only A. oreini were chosen for the histopathological investigation. The intestinal tissues with parasites in situ were fixed and processed for routine histological investigations. About 12.7% of the snowtrout were found to harbor A. oreini infection. With heavy worm burden, the aggregation of worms and increased mucus secretion were noted in infected intestines. The worm scolex lacked a specialized attachment organ and penetrated deeply into the intestinal wall. The pathology induced by this worm in the gut included mucosal damage at the site of attachment and the compression of villi adjacent to the strobila. Intense cellular response induced by the worm at the site of attachment was also observed.