Highly Pathogenic Avian Influenza A(H5N1) Virus Clade Infections in Wild Terrestrial Mammals, United States, 2022

Emerg Infect Dis. 2023 Dec;29(12):2451-2460. doi: 10.3201/eid2912.230464.


We describe the pathology of natural infection with highly pathogenic avian influenza A(H5N1) virus of Eurasian lineage Goose/Guangdong clade in 67 wild terrestrial mammals throughout the United States during April 1‒July 21, 2022. Affected mammals include 50 red foxes (Vulpes vulpes), 6 striped skunks (Mephitis mephitis), 4 raccoons (Procyon lotor), 2 bobcats (Lynx rufus), 2 Virginia opossums (Didelphis virginiana), 1 coyote (Canis latrans), 1 fisher (Pekania pennanti), and 1 gray fox (Urocyon cinereoargenteus). Infected mammals showed primarily neurologic signs. Necrotizing meningoencephalitis, interstitial pneumonia, and myocardial necrosis were the most common lesions; however, species variations in lesion distribution were observed. Genotype analysis of sequences from 48 animals indicates that these cases represent spillover infections from wild birds.

Keywords: United States; avian influenza; bobcat; clade; coyote; fisher; fox; highly pathogenic avian influenza virus; influenza; influenza A(H5N1); meningitis/encephalitis; opossum; raccoon; respiratory infections; skunk; viruses; wild terrestrial mammals; zoonoses.

MeSH terms

  • Animals
  • Animals, Wild
  • Foxes
  • Influenza A Virus, H5N1 Subtype* / genetics
  • Influenza in Birds* / epidemiology
  • Mammals
  • Mephitidae
  • United States / epidemiology