The United States Department of Agriculture (USDA) has initiated mandatory testing of the nation’s raw milk supply for avian influenza, commonly known as bird flu, in a bid to curb the virus’s spread among dairy cows. This move, effective December 16, 2024, reflects a heightened effort to monitor and control the H5N1 virus, which first appeared in US dairy cows in March of the same year. While the risk to humans remains low due to pasteurization processes that effectively neutralize the virus in commercially available milk, the USDA aims to build confidence among farmers and workers regarding the safety of their animals and prevent further transmission across the country. The initial phase of testing will focus on six states: California, Colorado, Michigan, Mississippi, Oregon, and Pennsylvania.
The decision to implement mandatory testing arrives after months of advocacy from veterinarians, farmers, scientists, and academics, who recognized the need for a comprehensive understanding of the virus’s prevalence within the dairy industry. Prior efforts to encourage voluntary testing met with resistance from dairy farmers and processors concerned about potential economic repercussions and other negative consequences. However, the continued spread of the virus, affecting over 700 herds in 15 states since March, underscores the urgency of the situation and the need for proactive measures to protect the agricultural sector. The USDA’s action is seen as a significant step towards gaining better control over the spread of H5N1.
The mandatory testing order requires dairy farmers and handlers of raw milk intended for pasteurization to provide samples for bird flu testing upon request. Positive test results must be reported to the USDA, and herd owners are obligated to provide information necessary for tracing the disease’s trajectory within cattle populations. This measure builds upon a previous federal order issued in April 2024, which mandated testing of specific dairy cattle before interstate transport and required reporting of positive cases. Despite this earlier intervention, the virus continued its spread, highlighting the need for more comprehensive surveillance and control measures.
The presence of the H5N1 virus in raw milk poses a significant risk, as tests reveal high viral loads in milk from infected cows. While pasteurization effectively eliminates the virus in commercially processed milk, the consumption of raw, unpasteurized milk can expose individuals to the virus. At least 58 human cases of bird flu have been reported in the US, primarily among farm workers who had close contact with infected cows, including exposure to their milk, or infected poultry. The virus has also been detected in wild birds and several other animal species, indicating a broader ecological concern.
The USDA’s mandatory testing initiative seeks to address the ongoing challenge of controlling the H5N1 virus within the dairy industry and prevent further spread. This comprehensive approach aims to provide greater transparency and understanding of the virus’s prevalence, enabling more effective interventions to protect animal health and minimize economic losses. The order also emphasizes the importance of collaboration between government agencies, industry stakeholders, and scientific experts in tackling this complex issue. The USDA remains committed to working with partners across the agricultural sector to contain and ultimately eliminate the virus from the nation’s dairy herds.
While the risk to the general public from consuming pasteurized milk remains low, the USDA continues to caution against drinking raw, unpasteurized milk due to the potential presence of various harmful pathogens. Recent incidents, such as the quarantine of a California farm and the recall of raw milk products due to H5N1 contamination, underscore the risks associated with consuming unpasteurized dairy products. The mandatory testing initiative aims to strengthen safeguards within the dairy industry and reduce the potential for human exposure to the virus. The USDA’s ongoing efforts, coupled with continued research and collaboration, are crucial in mitigating the impact of H5N1 on both animal and human populations.
