engleski

Gastric lesions in dolphins stranded along Eastern Adriatic coast

Stranded cetaceans are often found with gastric lesions associated with the presence of parasites, most frequently nematodes of the genus Anisakis and heterophyd digenean trematode Pholeter gastrophilus. In this study we present histopathology mainly, but not exclusively related to these two parasite species. Macroscopically, the lesions associated with the presence of Anisakis spp. were characterized by the presence of ulcers within the gastric mucosa while the digenean Pholeter gastrophilus was within large submucosal fibrotic nodules in the gastric wall. Anisakis- induced alterations included severe ulcerative gastritis with mixed inflammatory infiltrate often associated with colonies of bacteria, and mild to moderate granulomatous gastritis with eosinophilic infiltrate. P. gastrophilus associated lesions were characterized by fibrogranulomatous gastritis with mixed inflammatory infiltrate. Additionally, immunohistochemical (IHC) analysis of P. gastrophilus lesions was consistent with the histopathologic findings, revealing inflammation- mediated stimulation. IHC-positive localization of CD3+, iNOS+ and caspase-3+ cells suggests intensive accumulation of cytotoxic T cells, proinflammatory cytokines and execution-phase of cell apoptosis at the parasitized area. In contrast, mechanical damage, rather than visible inflammatory response could be observed at the site of attachment of Braunina cordiformis recorded in four animals. Lesions not associated with presence of parasites were mostly characterized by focal loss of superficial epithelial cells and accumulation of brown hemosiderin-like pigment or fibrous gastritis with lymphoplasmacytic infiltrate. In light of these results, we argue that observed “tolerant” host- parasite interactions that lead toward gastric lesions, do not represent a cause of death and stranding of cetaceans included in this study.

gastric lesions ; cetaceans ; Anisakis spp. ; Pholeter gastrophilus ; Braunina cordiformis ; Adriatic Sea

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