Abstract Title
Highly pathogenic avian influenza surveillance and detections in free-ranging wild mammals in Alaska
Abstract
In 2022, Alaska’s passive surveillance program detected the first mortalities due to highly pathogenic avian influenza (HPAI) infection in bears (Ursus spp.) and red foxes (Vulpes vulpes) in Alaska including the first case worldwide in a brown bear (Ursus arctos.). The cases were widely dispersed across Alaska and included three distinct genotypes (A3, an unreassorted Japan-like virus representing a 3rd introduction of 2.3.4.4b into Americas, genotype B3.2, very common across the US during fall 2022, and genotype B4) suggesting multiple introductions and spill-over events from wild birds. Each had a history of neurologic signs or acute death. Gross lesions in bears included injected brain with swelling. Histopathologically there was severe non-suppurative necrotizing encephalitis with neuronal necrosis, with moderate cuffing of vessels and infiltration of the parenchyma by lymphoid cells, edema and scattered glial nodules. Both bears had variable nonsuppurative and necrotizing hepatitis and nephritis. The brown bear had degenerative myopathy, myositis and enterocolitis. The black bear had multifocal pancreatic necrosis, nonsuppurative and necrotizing retinitis and adrenalitis. Immunohistochemistry for avian influenza on the brown bear tissues was positive in neurons and glial cells, superficial enterocytes and myenteric plexus neurons, rare bronchiolar epithelial cells, myocytes and renal tubules. One red fox was also infected with rabies virus, the first reported co-morbidity of HPAI and rabies in any animal. Subsequent surveillance of tissue and swabs obtained from over 200 wild mammals live-captured or found dead during 2023-24, detected three additional cases in red fox, including a co-infection with canine distemper virus.
Co-Author(s)
Kimberlee Beckmen, Alaska Dept. of Fish and Game, Kathleen Burek Huntington, Alaska Veterinary Pathology Services, Terry Spraker, Colorado State Veterinary Diagnostic Laboratory, Robert Gerlach, Alaska Office of the State Veterinarian, Camilla Lieske, Alaska Dept. of Fish and Game
Abstract Category
Avian influenza in mammals, pandemic preparedness, and one health