As of 5/7/24, 36 dairy herds across nine states have been identified as having Highly Pathogenic (HP) H5N1 infections. These states are (in alphabetical order): Colorado, Idaho, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota, and Texas.

On April 24, the USDA announced a new rule requiring dairy cattle to receive a negative test for influenza A virus at an approved National Animal Health Laboratory Network (NAHLN) laboratory before transportation across state lines. More information on appropriate biosecurity can be found in the USDA’s recommendations.

Monitoring for HPAI in commercial and backyard poultry and wild birds continues, with new cases reported in the last 30 days.

Although Highly Pathogenic Avian Influenza (HPAI) is typically a poultry disease, H5 HPAI has been found in at least 19 species of mammals as of 5/7/24. Updated information about HPAI detections can be found at the United States Department of Agriculture (USDA).

A group of 22 international experts on virus evolution posted a preliminary two-part report on the genomic epidemiology of the H5N1 outbreak in US dairy cows. They posted their report on Virological.org, a hub for prepublication data designed to assist with public health activities and research.