Histological damage and inflammatory response elicited by Monobothrium wageneri (Cestoda) in the intestine of Tinca tinca (Cyprinidae)

Immunopathological and ultrastructural studies were conducted on the intestines of 28 tench, collected from Lake Piediluco, of which 16 specimens harboured tight clusters of numerous M. wageneri attached to the intestinal wall. The infection was associated with the degeneration of the mucosal layer and the formation of raised inflammatory swelling surrounding the worms. At the site of infection, the number of granulocytes in the intestine of T. tinca was significantly higher than the number determined 1 cm away from the site of infection or the number found in uninfected fish. Using transmission electron microscopy, mast cells and neutrophils were frequently observed in close proximity to, and inside, the intestinal capillaries; often these cells were in contact with the cestode tegument. At the host-parasite interface, no secretion from the parasite's tegument was observed. Intense degranulation of the mast cells was seen within the submucosa and lamina muscularis, most noticeably at sites close to the tegument of the scolex. In some instances, rodlet cells were encountered in the submucosa. In histological sections, hyperplasia of the mucous cells, notably those giving an alcian blue positive reaction, were evident in the intestinal tissues close to the swelling surrounding the worms. Enhanced mucus secretion was recorded in the intestines of infected tench.The pathological changes and the inflammatory cellular response induced by the caryophyllidean monozoic tapeworm M. wageneri within the intestinal tract of an Italian population of wild tench is reported for the first time.Monobothrium wageneri Nybelin, 1922 was originally described from specimens collected from wild Tinca tinca (L.) caught in northern Italy during the nineteen century. Since this first report, this tapeworm has been subsequently reported in Poland, Bohemia and the United Kingdom [1]. Several species of caryophyllidean cestodes are recorded from tench populations across Continental Europe, but