Highly Pathogenic Avian Influenza (HPAI) viruses can spread from wild birds to domestic poultry and other avian and animal species. HPAI viruses are highly contagious and frequently cause fatal disease primarily affecting poultry. They may also be referred to as bird or avian flu.
2024 HPAI H5N1 Outbreak (Dairy Cows)
Since late March 2024, the US Department of Agriculture (USDA), US Centers for Disease Control and Prevention (CDC), US Food and Drug Administration (FDA), and state veterinary and public health officials have been investigating outbreaks of influenza A(H5N1) in dairy cows and the related exposures that have since followed. The outbreak has grown to encompass impacts to humans, animals (wild birds, domestic poultry, livestock [particularly dairy cattle], other wild mammals, and pets) and food products.
APHL is coordinating with these federal partners and public health laboratories during the response to mitigate the impact of HPAI on both animal and public health. APHL provides training, guidance and technical assistance to support laboratory work.
These links provide current situational updates and guidance from key HPAI Response Partners:
HPAI Testing and Surveillance Information
Public Health Laboratories
Public health laboratories in all 50 states are equipped for detecting influenza A (H5N1) viruses, and 26 APHL member laboratories test milk under the Pasteurized Milk Ordinance. Additional PHLs are also setting up enhanced wastewater surveillance and milk testing to give better situational awareness.
PHLs perform influenza virus testing for diagnosis, routine surveillance and novel influenza virus detection. In conjunction with CDC, state and local public health partners also continue to monitor people in the US who have been exposed to infected birds, poultry, dairy cattle or other animals for 10 days after their last exposure. The latest data on numbers of specimen tested for national flu surveillance as well as targeted H5 surveillance is available from the CDC.
HPAI Response Resources
Laboratory Testing Resources
Influenza Surveillance and Public Health Action Resources
Additional Resources