NEMATODE (OTOSTRONGYLUS-CIRCUMLITUS) INFESTATION OF NORTHERN ELEPHANT-SEALS (MIROUNGA-ANGUSTIROSTRIS) STRANDED ALONG THE CENTRAL CALIFORNIACOAST

Between 1 January 1992 and 31 December 1995, 73 of 487 (15%) juvenile northern elephant seals (Mirounga angustirostris) that stranded along the central California coastline and were transported to a rehabilitat ion center had similar clinical signs. These signs included anorexia, depression, dehydration, and epistaxis, and were accompanied by a neut rophilia. Coagulation assays on five of these animals indicated all fi ve were in a state of disseminated intravascular coagulation. Sixty-fi ve of the 73 animals died, and post-mortem examination revealed heavy burdens of Otostrongylus circumlitus in the right ventricle and atrium of the hearts and pulmonary arteries, with occasional nematodes in th e bronchi and bronchioles. Histologic examination of 33 of these seals showed multiple pulmonary thromboses associated with a suppurative ar teritis and occasionally intravascular nematodes, suggesting dissemina ted intravascular coagulation triggered by an arteritis may be importa nt in causing mortality of elephant seals infested with O. circumlitus . This pathology, combined with the observation that death of juvenile northern elephant seals infected with O. circumlitus usually occurs p rior to the parasite reaching reproductive maturity, suggests this is a relatively recent host-parasite association.