A new study by the Centers for Disease Control and Prevention (CDC) has found that avian influenza (H5N1) has been spreading among dairy cows in the United States since last year. The outbreak has now affected 968 dairy herds, with 68 confirmed cases in humans and one death reported in the US.
Three cow veterinarians tested positive for bird flu antibodies, but none of them reported previous symptoms of influenza or conjunctivitis. This suggests that monitoring only symptomatic exposed workers may underestimate human infection. The CDC is now urging rapid identification of infected dairy cattle through herd and bulk milk testing to prevent further spread.
The outbreak highlights the importance of continued monitoring and vigilance. Dr. Rowland Kao, a professor of veterinary epidemiology, notes that while it’s too early to predict the long-term implications, the virus is doing things that bird flu hasn’t done before in terms of affecting mammal species geographically.
Currently, there have been no reported infections in humans or cattle in European countries, with low risk for the general population and moderate risk for those with exposure to infected animals. The US CDC study was delayed due to a freeze on health agency communications by President Donald Trump’s administration, but it provides valuable insights into the ongoing outbreak.
The rapid identification of infected dairy cattle is crucial to preventing further spread of the virus. As Dr. Kao emphasizes, “we don’t like surprises” when it comes to bird flu, and continued monitoring and vigilance are essential to mitigate its impact on human and animal health.
Source: https://www.euronews.com/health/2025/02/14/bird-flu-has-been-spreading-undetected-in-cows-and-vets-according-to-us-cdc-report