In response to the unprecedented outbreak of H5N1 avian influenza in U.S. dairy cattle in early 2024, researchers at the University of Wisconsin–Madison, in collaboration with national partners, launched a series of federally supported studies to assess the virus’s impact on public health and food safety. Their findings offer critical reassurances for consumers and policymakers.
Key results, published in The New England Journal of Medicine (May 2024) and Nature (July 2024), confirm the following:
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Raw milk with H5N1 is infectious, posing a risk to mammals, including humans. However, pasteurization effectively inactivates the virus, ensuring that commercial milk products remain safe to consume.
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Ferrets exposed to H5N1 through raw milk became infected but did not spread the virus through the air, suggesting limited risk of airborne transmission from infected dairy products.
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A particularly virulent H5N1 strain isolated from a Texas dairy worker was found to be lethal to ferrets in very low doses, raising questions about viral behavior across species. Fortunately, this strain is no longer circulating in nature.
The research has provided valuable guidance for managing farm operations and dairy safety, reinforcing the importance of milk pasteurization and continued surveillance as H5N1 evolves.
