Pathology associated with Contracaecum rudolphii (Nematoda: Anisakidae) infection in the great cormorant Phalacrocorax carbo (L. 1758)

This is a report of lesions associated with the nematode Contracaecum rudolphii (Nematoda: Anisakidae) from the proventriculus of the great cormorant, Phalacrocorax carbo (L. 1758). The study was undertaken as part of a health monitoring program for P. carbo, which is endangered and thus protected within the European continent. Cormorants were collected by gun-shot from north-eastern Poland in the spring of 2006, four birds were necropsied on site and the gastrointestinal tract was examined for the presence of nematodes. The birds came from a region with noted increases in the cormorant population over the last decade. Esophageal and gastric sections with parasites in situ were fixed in formalin and processed routinely for paraffin embedding, stained with H&E and examined by brightfield microscopy. Parasite associated lesions consisted of severe, ulcerative gastritis at the attachment sites, and diffuse granulomatous gastritis in adjacent areas. Eosinophilic material speculated to be the parasite-derived excretory-secretory product was consistently forming the parasite-host boundry at the attachment points. Although the parasite-associated gastric lesions were focally severe, all examined birds appeared in good body condition. Because only four birds were investigated in this study, the potential contribution of C. rudolphii to morbidity and mortality in great cormorants needs to be examined further.