New research has examined how long influenza viruses, including the highly pathogenic H5N1 strain, remain viable in unpasteurized milk. The study, which has not yet been peer-reviewed, provides insights into potential transmission risks associated with contaminated dairy products.

The research follows the March 2024 identification of H5N1 highly pathogenic avian influenza virus in U.S. dairy cattle . Scientists discovered this virus after investigating significantly reduced milk production across affected farms. Genetic analysis indicated the virus was first introduced to cattle populations in late 2023.

Unlike typical respiratory influenza infections in mammals, H5N1 in cattle produces extremely high levels of viral shedding in milk. The virus has spread to over a thousand cattle herds

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