West Nile Virus Encephalitis, Myocarditis, and Myositis in a Hawk

West Nile Virus Encephalitis, Myocarditis, and Myositis in a Hawk

History: A three month old Hawk with lethargy, voice change and green urates for 3 days.

Clinical Pathology: Monocytosis and toxic heterophils.

Gross Lesions:

The keel was mildly prominent but there were adequate body fat stores, and minimal autolysis. The spleen was diffusely tan with small multifocal dark red foci. The left lung contained a 5x5mm tan area on its ventral edge, proximal to the heart. The right lung contained a 5x7mm purple, slightly depressed area and was slightly redder than the left lung. The right humerus contained multifocal areas of dark red, gelatinous material within the medullary cavity.  No other gross abnormalities were found.


Brain (Cerebrum and Cerebellum): Within the neuropil and meninges, the blood vessel walls are infiltrated and surrounded by many lymphocytes and fewer plasma cells. The neuropil is also diffusely infiltrated by
numerous glial cells.

Brain, lymphocytic perivascular cuffing

Brain, lymphocytic perivascular cuffing

Heart (myocardium): Scattered multifocally within the myocardium degenerate muscle fibers are replaced by necrotic debris, lymphocytes and plasma cells.

Heart, lymphocytic myocarditis

Heart, lymphocytic myocarditis with necrosis

Similar lesions were found in the skeletal muscle.


The heart and skeletal muscle were the most positive tissues with immunohistochemistry for WNV.

Heart, WNV Immunohistochemistry (positive)

Heart, WNV Immunohistochemistry (positive)

PCR: All tissues were positive for WNV by PCR


About Brian

Anatomic Pathologist, VetPath Services, Stone Ridge, NY- musculoskeletal, oral/dental, and sinonasal diseases
This entry was posted in Necropsy Cases and tagged , , , , . Bookmark the permalink.

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