Parasites in harbour seals (Phoca vitulina) from the german wadden sea between two phocine distemper virus epidemics

Parasites were collected from 107 harbour seals (Phoca vitulina) found on the coasts of Schleswig-Holstein, Germany, between 1997 and 2000. The prevalence of the parasites and their associated pathology were investigated. Eight species of parasites, primarily nematodes, were identified from the examined organs: two anisakid nematodes (Pseudoterranova decipiens (sensu lato), Contracaecum osculatum (sensu lato)) from the stomach, Otostrongylus circumlitus (Crenosomatidae) and Parafilaroides gymnurus (Filaroididae) from the respiratory tract, one filarioid nematode (Acanthocheilonema spirocauda) from the heart, two acanthocephalans, Corynosoma strumosum and C. semerme (Polymorphidae), from the intestine and an ectoparasite, Echinophthirius horridus (Anoplura, Insecta). Lungworm infection was the most prominent parasitological finding and secondary bacterial bronchopneumonia the most pathogenic lesion correlated with the parasites. Heavy nematode burdens in the respiratory tract were highly age-related and more frequent in young seals. A positive correlation was observed between high levels of pulmonary infection and severity of bronchopneumonia. The prevalence of lungworms in this study was higher than in seals that died during the 1988/1989 Phocine Distemper Virus epidemic, and the prevalence of acanthocephalans and heartworms had decreased compared to findings from the first die-off.