Avian Influenza A(H5) Outbreak | Center for Outbreak Response Innovation

Current US Outbreak

As of November 19, 2024:

Critical Epidemiological Updates

Health officials have confirmed that the Canadian teen in critical care for avian influenza tested positive for H5N1 clade 2.3.3.4b genotype D1.1, which has been detected among poultry farmers in the US but is different than the H5N1 clade 2.3.3.4b genotype B3.13 detected in cattle and humans in contact with cattle. The source of the infection remains unknown and the investigation is ongoing.
On November 18, Hawaii health officials confirmed the presence of H5N1 in a flock of birds that were present at pet fair open to the public on November 2. Health officials report that the birds became symptomatic several days after the fair. Individuals who had contact with ducks or geese at the fair are being encouraged to monitor for symptoms of flu-like illness or conjunctivitis, although the likelihood of infection is expected to be low. No suspected human cases of H5N1 in connection with the event have been identified at this time.

Routine Surveillance Updates

The Centers for Disease Control and Prevention (CDC) is reporting 53 confirmed human cases of H5 in the United States as of November 19, 2024.
The United States Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) has reported 216 new infected cattle herds across four states (UT, ID, CA)in the last 30 days, bringing the total for the outbreak to 549 cattle herds in 15 state. This represents a slight increase compared to the previous 30 days.
CDC reports that for the duration of the outbreak, 250 tests for poultry workers and 131tests for dairy workers have been sent to CDC for H5N1 testing, resulting in a positivity rate since March 2024 of 8.4% (21/250) and 20.6% (31/131), respectively.