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Volume 30, Number 8—August 2024
Dispatch

Highly Pathogenic Avian Influenza Virus A(H5N1) Clade 2.3.4.4b Infection in Free-Ranging Polar Bear, Alaska, USA

Raphaela Stimmelmayr1Comments to Author , David Rotstein1, Mia Kim Torchetti, and Robert Gerlach
Author affiliations: North Slope Borough, Utqiagvik, Alaska, USA (R. Stimmelmayr); University of Alaska, Fairbanks, Alaska, USA (R. Stimmelmayr); Marine Mammal Pathology Services, Olney, Maryland, USA (D. Rotstein); US Department of Agriculture Animal and Plant Health Inspection Service, Ames, Iowa, USA (M.K. Torchetti); Alaska Department of Environmental Conservation, Anchorage, Alaska, USA (R. Gerlach)

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Figure

Histologic analysis of brain tissue from a dead free-ranging polar bear infected with highly pathogenic avian influenza virus A(H5N1) clade 2.3.4.4b, Alaska, USA. A) Hematoxylin and eosin staining of brain tissue section showing meningoencephalitis. Arrow indicates mixed inflammatory cells within and around blood vessels and hypertrophied vascular endothelial cells. Star indicates necrotic neurons and increased number of microglial cells within the parenchyma. Original magnification ×400. B) Arrow indicates influenza A virus within the neuronal perikaryon (red staining) observed by immunohistochemistry of formalin-fixed paraffin-embedded brain sections. Original magnification ×400.

Figure. Histologic analysis of brain tissue from a dead free-ranging polar bear infected with highly pathogenic avian influenza virus A(H5N1) clade 2.3.4.4b, Alaska, USA. A) Hematoxylin and eosin staining of brain tissue section showing meningoencephalitis. Arrow indicates mixed inflammatory cells within and around blood vessels and hypertrophied vascular endothelial cells. Star indicates necrotic neurons and increased number of microglial cells within the parenchyma. Original magnification ×400. B) Arrow indicates influenza A virus within the neuronal perikaryon (red staining) observed by immunohistochemistry of formalin-fixed paraffin-embedded brain sections. Original magnification ×400.

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1These authors contributed equally to this article.

Page created: June 24, 2024
Page updated: July 21, 2024
Page reviewed: July 21, 2024
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