NEUROTROPIC VELOGENIC NEWCASTLE-DISEASE IN CORMORANTS IN MICHIGAN - PATHOLOGY AND VIRUS CHARACTERIZATION

Excessive unexplained mortality was observed in flocks of double-crest ed cormorants located at Snake Island in Green Bay, Michigan, in June 1992. Clinical signs included weakness, lethargy, diarrhea, respirator y distress, paralysis of the wings and legs, torticollis, and incoordi nation. The most significant and consistent gross lesions included ede ma of the eyelids and periocular tissues, pulmonary edema and congesti on, marked splenomegaly, hepatic necrosis, and scattered hemorrhages i n visceral organs. Histologically, the principal alterations were seve re lymphocytic meningoencephalitis and myelitis, as well as splenic ly mphoid necrosis with hemorrhage. A type 1 paramyxovirus was isolated f rom the affected birds and characterized as a velogenic neurotropic st rain of Newcastle disease virus. Since the infection occurred in free- living migratory birds, there exists the potential for spread of the v irus over a large area, thus posing a hazard to domestic poultry.