CDC Confirms Second Human H5 Bird Flu Case in Michigan; Third Case Tied to Dairy Outbreak

A second human case of highly pathogenic avian influenza (HPAI) A(H5) virus infection has been identified in the state of Michigan. This is the third human case associated with an ongoing multistate outbreak of A(H5N1) in U.S. dairy cows. None of the three cases are associated with the others. As with the previous two cases (one in Texas, one in Michigan), the person is a dairy farm worker with exposure to infected cows, making this another instance of probable cow-to-person spread. This is the first human case of H5 in the United States to report more typical symptoms of acute respiratory illness associated with influenza virus infection, including A(H5N1) viruses. CDC continues to closely monitor available data from influenza surveillance systems , particularly in affected states, and there has been no sign of unusual influenza activity in people, including no increase in emergency room visits for influenza and no increase in laboratory detection of human influenza cases.

Based on the information available at this time, this case does not change CDC’s current A(H5N1) bird flu human health risk assessment for the U.S. general public because all three sporadic cases had direct contact with infected cows. Risk depends on exposure, and in this case, the relevant exposure is to infected animals. The risk to members of the general public who do not have exposure to infected animals remains 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 infected animals, are at greater risk of infection and should take precautions.