Update on 2024 H5N1 Influenza A Virus Outbreak in the United States

Update on 2024 H5N1 Influenza A Virus Outbreak in the United States

The H5N1 influenza virus has been confirmed in 473 cattle cases in 15 states (California, Utah, Texas, Kansas, Michigan, New Mexico, Ohio, Idaho, South Dakota, North Carolina, Colorado, Minnesota, Wyoming, Iowa, and Oklahoma) as of November 8. In addition, the U.S. Department of Agriculture (USDA) has confirmed one case of H5N1 in Alpaca (May 16, 2024) and one case in Swine (October 30, 2024).

Since April 2024, the Centers for Disease Control and Prevention, working with state public health departments, has confirmed H5 bird flu infections in 46 people in the United States. Twenty of these cases were associated with exposure to H5N1 bird flu-infected poultry and 25 were associated with exposure to sick or infected dairy cows. The source of the exposure in one case, which was reported by Missouri on September 6, could not be determined. Serological testing of the contacts of the Missouri case has been reported, and that investigation has concluded.

Highly pathogenic avian influenza (HPAI) A(H5) viruses have been detected in U.S. wild aquatic birds, commercial poultry and backyard or hobbyist flocks beginning in January 2022. As of November 7, 2024, the HPAI A(H5) viruses have been identified in 1,198 outbreaks in 48 states since 2022. Over 105 million U.S. wild aquatic birds, commercial poultry, and backyard or hobbyist flocks have been affected during this outbreak. The HPAI A(H5) viruses have been identified in 10,458 wild birds in 49 states since December 30, 2021. Through October 22, 2024, HPAI EA H5N1 has been detected in 23 mammal species since 2022.

Conservation partners developed a plan in 2015 to implement national level surveillance for avian influenza viruses (AIVs) in wild waterfowl. Collaborating entities include the USDA Animal and Plant Health Inspection Service (APHIS) Wildlife Services, National Wildlife Disease Program, and Veterinary Services; the U.S. Department of the Interior U.S. Geological Survey and U.S. Fish and Wildlife Service; and the National Flyway Council. The Implementation Plan developed in July 2024 supports the collection of biological samples, diagnostic testing, data management, and analysis of data obtained by USDA-APHIS-Wildlife Services, other federal agencies, state wildlife agencies, universities, and tribal cooperators for this fall.

November 15, 2024