engleski

Severe helminthic infection of the wild brown trout (Salmo trutta) in Cetina River, Croatia

Elevated mortalities of brown trout (Salmo trutta m. fario) and grayling (Thymallus thymallus) were noticed in the Cetina River at the end of the February. Local anglers collected the samples of moribund fish and submitted them to the laboratory for examination. Ectoparasitological, bacteriological and virological examination did not reveal any ectoparasite, bacteria or viral agents, however pyloric caeca and intestine were tightly packed with mixed infection of Echinorhynchus truttae (Acanthocephala, Echinorhynchidae) and Cyathocephalus truncatus (Cestoda, Spathebothridae). Histopathology revealed complete desquamation of functional epithelial mucosa in the intestine. In between attached parasites, intestinal lumen was filled with thick necrotic tissue mass of sloughed enterocytes, mucus, bacteria and lymphocytes. While cestodes rarely cause death, and the acanthocephalan proboscis did not perforated intestinal wall, ruling out general septicaemia as a cause of death, histopathological examination suggests that high load of intestinal helminths triggered long-term malnutrition, eventually leading to trout emaciation and mortalities.

Brown trout; Salmo trutta m. fario; grayling; Thymallus thymallus; Echinorhynchus truttae; Cyathocephalus truncatus

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