Lungworm infection with Otostrongylus circumlitus in a free-ranging harbor seal (Phoca vitulina)

A young wild harbor seal (Phoca vitulina) was found stranded on the North Sea coast at Kok- sijde (Belgium)and was admitted to a rehabilitation center where it died one day later. Full ne- cropsy with histopathology was performed. Gross examination revealed severe diffuse hemorr- hagic and emphysematous pneumonia with the presence of 6-10 cm-large nematodes. The nema- todes were found in the trachea, large bronchi, right heart and pulmonary arteries, and subsequently identified as Otostrongylus circumlitus. Histologic examination demonstrated severe eosinophilic to granulomatous bronchointerstitial pneumonia with intralesional nematodes. It was concluded that the seal died of severe verminous pneumonia. In this case report, the importance of lungworm infection, which is a common and critical disease in young seals, is highlighted.

PULMONARY NEMATODOSIS OF THE BAIKAL SEAL (PUSA SIBIRICA)

Current data on the prevalence of pulmonary nematodes in Baikal seals and their effect on the host organism are not available. In October 2020, annual research expedition in order to study population, monitoring of territorial distribution and role of the Baikal seal in a closed ecosystem was undertaken. During this expedition 71 Baikal seals (Pusa sibirica) were caught and examined. The material was collected by complete helminthological dissection of individual organs, and samples were taken for histological examination. Found helminths were fixed in 70% ethanol, and cross-sections were prepared from organs and tissues. Pulmonary nematodes were recorded in 62 seals (87.3%). Parafilaroides krasheninnikovi were found in 62 seals (87.3%); large number of helminths were located on the surface and inside the lungs. Despite the high intensity and prevalence of the invasion, there were no serious pathological changes associated with P. krasheninnikovi. Otostrongylus circumlitus was found in 5 Baikal seals. Against the background of the O. circumlitus invasion in the studied Baikal seals, the development of limited granulomatous pneumonia foci was noted. However, the intensity (3.2 specimens) and prevalence (7%) of this invasion were low.