Detections of highly pathogenic avian influenza (HPAI) H5N1 in North America occurred in December 2021 in Newfoundland and Labrador, Canada. Since then, HPAI H5 and H5N1 viruses have continued to spread, and have been confirmed in wild birds, backyard flocks, commercial poultry facilities, and wild mammals in both Canada and the United States.
Total Number of HPAI Detections in Wild Birds Since Dec 2021 (Updated May 21, 2026)
Most Recent HPAI Detections in Wild Birds (April 21-May 21, 2026)
Source: USDA: https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/wild-birds?page=1
Detections of HPAI in Wild Mammals (Updated May 2026)
Source: USDA: https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/mammals?page=1
Recent HPAI News:
March 6, 2026: National Wildlife Health Center- Highly Pathogenic Avian Influenza Continues to Affect Wild Birds Across All Four U.S. Flyways
Feb 27, 2026: Avian flu strikes California’s northern elephant seals; area quarantined
WHAT IS HPAI?
Avian influenza (AI) is caused by an influenza type A virus which can infect poultry (such as chickens, turkeys, pheasants, quail, domestic ducks, geese, and guinea fowl) and is carried by free flying waterfowl such as ducks, geese and shorebirds. AI viruses are classified by a combination of two groups of proteins: hemagglutinin or “H” proteins, of which there are 16 (H1–H16), and neuraminidase or “N” proteins, of which there are 9 (N1–N9). Many different combinations of “H” and “N” proteins are possible. Each combination is considered a different subtype and can be further broken down into different strains which circulate within flyways/geographic regions. AI viruses are further classified by their pathogenicity (low or high)—the ability of a particular virus strain to produce disease in domestic poultry. [USDA APHIS]
CLINICAL SIGNS
Sudden death; lack of energy, appetite and coordination; purple discoloration and/or swelling of various body parts; diarrhea; nasal discharge; coughing; sneezing; and reduced egg production and/or abnormal eggs. [USDA APHIS]
TRANSMISSION
Transmitted directly from wild birds to domestic poultry or indirectly e.g. through contaminated material. The virus spreads directly from bird to bird via airborne transmission or indirectly, through faecal contamination of material, feathers or feed. [USDA APHIS]
ZOONOTIC POTENTIAL AND ONE HEALTH ASPECTS
Zoonotic but currently low risk of transmission to humans. High risk of transmission between wild and domestic bird species. Spring and fall migration increases transmission risk and geographic impacts. Wild birds, especially waterfowl, can serve as asymptomatic carriers.
