CDC Reports Second Human Case of H5 Bird Flu Tied to Dairy Cow Outbreak

On May 22, CDC reported that a human case of highly pathogenic avian influenza (HPAI) A(H5) (“H5 bird flu”) virus infection in the United States has been identified in Michigan. This is the second case associated with an ongoing multistate outbreak of A(H5N1) in dairy cows. CDC has been watching influenza surveillance systems closely, particularly in affected states, and there has been no sign of unusual influenza activity in people, including in syndromic surveillance.

Based on the information available, this infection does not change CDC’s current H5N1 bird flu human health risk assessment for the U.S. general public, which the agency considers to be low. However, this development underscores the importance of recommended precautions in people with exposure to infected or potentially infected animals. People with close or prolonged, unprotected exposures to infected birds or other animals, including livestock, or to environments contaminated by infected birds or other animals, are at greater risk of infection.

In addition to enhanced and targeted surveillance, CDC has held numerous weekly engagements with state and local health departments on increasing their preparedness posture and with groups representing farmworkers. On May 22, CDC held an HPAI A (H5N1) response update call with public health partners to alert them to the new case and answer questions. CDC also has updated interim recommendations for worker protection to include those who work with dairy cows and in slaughterhouses.

For more information see Outbreak of Highly Pathogenic Avian Influenza A(H5N1) Viruses in U.S. Dairy Cattle and Detection of Two Human Cases — United States, 2024.