The US Department of Agriculture (USDA) has launched a National Milk Testing Strategy (NMTS) to monitor the spread of highly pathogenic avian influenza (HPAI), H5N1.  

Under the initiative, USDA’s Federal Order mandates dairy farms to provide unpasteurised milk samples for testing, aiming to enhance understanding of the virus's spread across the US dairy industry. 

It builds upon actions implemented by USDA and federal and state partners following the initial detection of H5N1 in dairy cattle in March 2024. 

This strategy, developed with input from state, veterinary, and public health stakeholders, aims to facilitate “comprehensive H5N1 surveillance”.  

According to Agriculture Secretary Tom Vilsack, the strategy will “provide a roadmap for states to protect the health of their dairy herds”. 

In April, the World Health Organization (WHO) highlighted the pandemic potential of H5N1, urging thorough investigation of human exposure.  

Although no human-to-human transmission has been recorded, animal-to-human cases are increasing.  

The USDA's testing system will help identify affected states and herds, supporting biosecurity measures to prevent further transmission. 

The Federal Order requires three main actions.  

First, dairy entities must share raw milk samples upon request.  

Second, herd owners with positive cattle must provide epidemiological data for contact tracing and surveillance.  

Third, private labs and state veterinarians must report positive results to the USDA. 

US Secretary of Health and Human Services (HHS) Xavier Becerra added: “Our primary responsibility at HHS is to protect public health and the safety of the food supply, and we continue to work closely with USDA and all stakeholders on continued testing for H5N1 in retail milk and dairy samples from across the country to ensure the safety of the commercial pasteurized milk supply.” 

The first round of testing under the NMTS is set to begin next Monday (16 December). Some states are already conducting compatible testing.  

The new Federal Order complements the USDA's April 24 mandate, which enforces mandatory testing of lactating dairy cows before interstate shipment and requires reporting of positive test results by private labs and state veterinarians.