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USDA Actions to Protect Livestock Health From Highly Pathogenic H5N1 Avian Influenza

Federal Order to assist with developing a baseline of critical information and limiting the spread of H5N1 in dairy cattle

WASHINGTON, April 24, 2024 – To further protect the U.S. livestock industry from the threat posed by highly pathogenic H5N1 avian influenza, USDA is sharing a number of actions that we are taking with our federal partners to help us get ahead of this disease and limit its spread.

Today, USDA’s Animal and Plant Health Inspection Service (APHIS) announced a Federal Order requiring the following measures, effective Monday, April 29, 2024:

Mandatory Testing for Interstate Movement of Dairy Cattle

  • Prior to interstate movement, dairy cattle are required to receive a negative test for Influenza A virus at an approved National Animal Health Laboratory Network (NAHLN) laboratory.
  • Owners of herds in which dairy cattle test positive for interstate movement will be required to provide epidemiological information, including animal movement tracing.
  • Dairy cattle moving interstate must adhere to conditions specified by APHIS.
  • As will be described in forthcoming guidance, these steps will be immediately required for lactating dairy cattle, while these requirements for other classes of dairy cattle will be based on scientific factors concerning the virus and its evolving risk profile.

Mandatory Reporting

  • Laboratories and state veterinarians must report positive Influenza A nucleic acid detection diagnostic results (e.g. PCR or genetic sequencing) in livestock to USDA APHIS.
  • Laboratories and state veterinarians must report positive Influenza A serology diagnostic results in livestock to USDA APHIS.

USDA has identified spread between cows within the same herd, spread from cows to poultry, spread between dairies associated with cattle movements, and cows without clinical signs that have tested positive. On April 16, APHIS microbiologists identified a shift in an H5N1 sample from a cow in Kansas that could indicate that the virus has an adaptation to mammals. Centers for Disease Control and Prevention (CDC) conducted further analysis of the specimen sequence, which did not change their overall risk assessment for the general public, because the substitution has been seen previously in other mammalian infections and does not impact viral transmission. Additionally, APHIS’ National Veterinary Services Laboratories found H5N1 in a lung tissue sample from an asymptomatic cull dairy cow that originated from an affected herd and did not enter the food supply.

The novel movement of H5N1 between wild birds and dairy cows requires further testing and time to develop a critical understanding to support any future courses of action. This Federal Order is critical to increasing the information available for USDA. Requiring positive test reporting will help USDA better under this disease and testing before interstate movement will limit its spread.

While we are taking this action today, it is important to remember that thus far, we have not found changes to the virus that would make it more transmissible to humans and between people. While cases among humans in direct contact with infected animals are possible, our partners at the U.S. Centers for Disease Control and Prevention (CDC) believe that the current risk to the public remains low.

Additionally, we continue to see affected cows recover after supported care with little to no associated mortality. We also continue to work with our partners in the states and industry to emphasize the critical importance biosecurity plays in limiting disease spread for all livestock and poultry.

You may view the Federal Order, which is effective on Monday, April 29, 2024.

Further, in an effort to maximize understanding and research on H5N1 in dairy cattle, on April 21, APHIS made publicly available 239 genetic sequences from the U.S. H5N1 clade influenza virus recently found in samples associated with the ongoing HPAI outbreak in poultry and wild birds, and the recent H5N1 event in dairy cattle. APHIS has also offered virus samples to interested researchers to facilitate epidemiological study. Increasing our understanding of this disease and how it spreads is critical to stopping it. This is why APHIS is urging dairy cattle producers and those who work in or with the industry to share epidemiological information from affected farms, even if they are not planning to move cattle interstate. APHIS further urges producer participation in public health assessments to continue to confirm worker safety and monitor for any potential changes in the virus that could impact transmissibility.

In addition, our partners in the U.S. Food and Drug Administration released an update on the ongoing work to ensure continued effectiveness of the federal-state milk safety system. It is important to emphasize that, based on the information and research available to us at this time, the U.S. Food and Drug Administration and USDA believe that our commercial milk supply is safe because of both the pasteurization process and the required diversion or destruction of milk from sick cows. Pasteurization has continuously proven to inactivate bacteria and viruses in milk. The FDA and USDA continue to work closely to collect and evaluate additional data and information specific to avian influenza in dairy cattle and to support state counterparts as this emerging disease in dairy cattle is managed.

As USDA continues to take steps to protect the health of livestock, the Department continues to work closely with federal partners at the CDC on protecting the health of people and FDA on protecting the safety of the food supply. The U.S. government is committed to addressing this situation with urgency.

To learn more about USDA’s response to HPAI in dairy cattle, visit


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