The US Department of Agriculture (USDA) is rolling out a national milk testing strategy to address the outbreak of highly pathogenic avian influenza (bird flu) H5N1 in dairy cattle.
The department has issued a new federal order requiring that raw (unpasteurised) milk samples be collected nationwide and shared with USDA for testing.
The strategy is designed to increase USDA’s understanding of the virus’ spread in the US through a “structured, uniform, and mandatory testing system”.
It is hoped that the testing will help to quickly identify which states, and specific herds within them, are affected with bird flu.
USDA said that the results will support “the rapid implementation of enhanced biosecurity measures” to decrease the risk of transmission to other livestock and inform efforts to protect farmworkers to help lower their risk of exposure.
USDA said it believes this additional step is needed to “proactively support effective biosecurity measures”, which is essential to contain and eliminate bird flu infections in livestock across the US dairy population.
The H5N1 bird flu strain was first detected in dairy cattle in the US in March 2024.
USDA will still require mandatory testing of lactating dairy cows prior to interstate shipment and that all privately owned laboratories and state veterinarians report positive test results connected with those tests. That federal order was made in April.
USDA
The new testing strategy requires dairy farms, bulk milk transporters, bulk milk transfer stations, or dairy processing facilities to share of raw milk samples when requested by the government.
Herd owners with positive cattle will be required to provide epidemiological information which enables contact tracing and disease surveillance.
Private laboratories and state veterinarians must also report positive results to USDA that come from tests done on raw milk samples drawn as part of the strategy.
The first round of silo testing is scheduled to begin next week, although some states are already conducting testing compatible with under the new strategy.
US Agriculture Secretary Tom Vilsack said that the new guidance from USDA was developed with state, veterinary and public health stakeholders and will facilitate comprehensive bird flu surveillance of the nation’s milk supply and dairy herds.
“Since the first HPAI detection in livestock, USDA has collaborated with our federal, state and industry partners to swiftly and diligently identify affected herds and respond accordingly.
“This new milk testing strategy will build on those steps to date and will provide a roadmap for states to protect the health of their dairy herds.
“Among many outcomes, this will give farmers and farmworkers better confidence in the safety of their animals and ability to protect themselves, and it will put us on a path to quickly controlling and stopping the virus’ spread nationwide,” he said.