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Protocols ensure safe movement of animals while mitigating the threat of New World Screwworm

WASHINGTON, D.C., February 1, 2025 – The United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) is announcing the resumption of cattle and bison imports from Mexico. Imports are scheduled to resume within the next several days.

To protect U.S. livestock and other animals, APHIS halted shipments of Mexican cattle and bison in November 2024 after a positive detection of New World screwworm (NWS) in southern Mexico. After extensive discussions between representatives from the countries, APHIS and Mexico agreed to and implemented a comprehensive pre-clearance inspection and treatment protocol to ensure safe movement and mitigate the threat of NWS. 

APHIS’ top priority is to protect American livestock from foreign pests. As part of the protocol signed between the countries, Mexico identified and prepared pre-export inspection pens in San Jeronimo, Chihuahua, and Agua Prieta, Sonora, which APHIS has now visited, inspected, and approved. Cattle and bison will be inspected and treated for screwworm by trained and authorized veterinarians prior to entering the pre-export inspection pens, where they will again undergo inspection by Mexican officials before proceeding to final APHIS inspection then crossing at the Santa Teresa and Douglas Ports of Entry, respectively. Cattle and bison approved for importation will also be dipped in a solution to ensure they are otherwise insect- and tick -free. The United States and Mexico are working closely to approve additional pre-export inspection pens and reopen trade through other ports of entry.

To support our efforts to keep NWS out of the United States, APHIS will continue working with partners in Mexico and Central America to eradicate NWS from the affected areas and to reestablish the biological barrier in Panama, which we have worked to maintain since 2006. 

In the last two years, screwworm has spread north of the barrier throughout Panama and into Costa Rica, Nicaragua, Honduras, Guatemala, El Salvador, Belize and now Mexico. This increase is due to multiple factors including new areas of farming in previous barrier regions for fly control and increased cattle movements into the region. APHIS is releasing sterile flies through aerial and ground release at strategic locations, focusing on Southern Mexico and other areas throughout Central America.  A complete list of regions APHIS recognizes as affected by screwworm as well as more detailed information on trade restrictions can be found on the USDA APHIS Animal Health Status of Regions website. 

Effective January 21, 2025, the Animal and Plant Health Inspection Service (APHIS) will again permit the importation of equines from Mexico with additional mitigations to guard against introduction of New World Screwworm (NWS). APHIS temporarily suspended livestock imports from Mexico after that country detected NWS on November 22, 2024. NWS (Cochliomyia hominivorax) is a devastating pest that can cause serious, often deadly damage to the affected animal. 

APHIS and Mexico’s National Service for Health, Safety, and Food Quality (SENASICA) have now developed an import protocol that details a stepwise NWS pre-clearance inspection and treatment plan based on APHIS regulations for importation of equines from NWS-affected regions. Equines will also undergo screwworm examinations during the required import quarantine. The protocol and associated health certification documents are available on the APHIS website.

In summary, equines must be inspected by an approved veterinarian for evidence of NWS infestation and treated with ivermectin or an equivalent APHIS-approved product within 3-5 days prior to entry into import quarantine. Oral ivermectin paste that is formulated for horses and administered per the manufacturer’s label may be used instead of injectable ivermectin. In addition, the equines must be inspected under direct supervision of a SENASICA veterinarian within 24 hours prior to entry into import quarantine and any visible wounds treated at that time. Certification of both inspections must be presented at the time of importation. APHIS will examine the equines for NWS on the first and last days of the 7-day import quarantine. Animals with evidence of NWS infestation at any point in the process are not eligible to import until they are treated, wounds are healed, and they are found free of NWS.

Please contact LAIPolicy@usda.gov with any questions regarding this announcement.

WASHINGTON, Jan. 08, 2024 – Today, the U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) announced that 15 additional states have enrolled in the National Milk Testing Strategy, bringing the total number of states to 28 in roughly one month since the program launched. These 28 states represent nearly 65% of the nation’s milk production. In addition, USDA is sharing updates on its expedited work to support vaccine development for use in poultry and bovine species, as part of a multi-faceted effort to fight the spread of H5N1.  

“Across the country, a strong network of public and private veterinarians, as well as state and local agriculture and health officials, have been working hand-in-hand with USDA to make the National Milk Testing Strategy as robust a weapon as possible in our fight against H5N1, and to ensure farmers have the information and tools they need to protect their businesses, their families, their workers, and ultimately their communities,” said Agriculture Secretary Tom Vilsack. “USDA remains fully committed to working with farmers and our public health partners to evolve our strategy based on our latest findings so we can keep people and animals safe from this virus.” 

Update on the National Milk Testing Strategy and on Detections of H5N1 in Dairy Cows 

Today, USDA is announcing the third tranche of states that are enrolled in the National Milk Testing Strategy, under which USDA and state and federal partners will gain a clearer picture of the presence of H5N1 among dairy herds in the United States to help inform the strategy and overall response efforts to prevent further spread of the virus. The 15 states enrolling in the strategy today include: Alabama, Arizona, Delaware, Iowa, Georgia, Kansas, Minnesota, New Jersey, New Mexico, Nevada, Oklahoma, Rhode Island, Tennessee, Utah, and Virginia. The addition of 15 states brings USDA closer to conducting mandatory, nationwide bulk milk surveillance in all 48 contiguous states.  

Also in the past 30 days, USDA has identified H5N1 detections in dairy herds in two states, California and Texas, with Texas’ most recent detection reported on Dec. 13, 2024. As of Jan. 8. 2025, California and Texas are the only states with known active detections, though the National Milk Testing Strategy may reveal additional herds over time. However, testing to date, including early NMTS testing, has so far reaffirmed the absence of H5N1 in other states and has not yet led to new detections. 

In December, USDA announced two earlier tranches of enrolled states, including California, Colorado, Michigan, Mississippi, Oregon, and Pennsylvania, which enrolled on December 6, 2024; and Indiana, Maryland, Montana, New York, Ohio, Vermont, and Washington, which enrolled on Dec, 17, 2024. USDA continues to work directly with states to bring them on board as quickly as possible while also accommodating state-specific needs based on their infrastructure, state personnel availability, and other considerations.  

The National Milk Testing Strategy involves five stages that describe the state’s testing activity and the presence of H5N1 in that state. Of the 28 states enrolled as of today, 11 states are considered to be in Stage 2, meaning they have state-level bulk tank sampling programs already underway. California is considered to be in Stage 3, meaning that it is an affected state that has rapid response measures in place to address detections. Two states are in Stage 1, meaning that silo testing is underway or is set to begin imminently. As new states join and initiate testing, USDA will update their status its National Milk Testing Strategy website and map linked here

Testing results from the National Milk Testing Strategy will be included in the routine testing reports shared by APHIS. Since the beginning of the outbreak in March 2024, over 110,000 samples have been tested through USDA’s National Veterinary Services Laboratory (NVSL) and the National Animal Health Laboratory Network (NAHLN), ranging from milk tests that represent multiple herds to individual test from wild or domestic animals. This testing is provided at no cost to producers and, prior to the launch of the National Milk Testing Strategy, had included at least one test from each of the 48 contiguous states. Positive detections are shared in real time with the U.S. Centers for Disease Control and Prevention through shared information systems, and whole genome sequences  are uploaded to the public databases GISAID (the Global Initiative on Sharing Avian Influenza Data) and the National Center for Biotechnology Information (NCBI) Sequence Read Archive (use search term “WGS of H5N1”). 

All newly affected herds, including any that are detected through the National Milk Testing Strategy, are reported on the website on the HPAI confirmed cases in livestock map. This interactive map shows known active detections in livestock as well as past detections; hovering over each state will show more information about the date of the state’s most recent detection and the total number of herds that were affected. The map can be adjusted to show detections over the past 30 days or over the course of the outbreak. 

In addition to the Dec. 6 Federal Order that underpins the National Milk Testing Strategy and requires raw (unpasteurized) milk samples nationwide be collected and shared with USDA for HPAI H5N1 testing, testing continues to occur under the first Federal Order issued in April 2024, requiring the testing of all lactating dairy cows prior to interstate transfer. Samples are also routinely collected through the Dairy Herd Status Program, which currently includes herds in 18 states; under testing programs that some states have designed pursuant to their unique authorities; prior to intrastate movement to fairs, exhibitions, or sales as part of state testing programs; or for producers interested in learning the status of their livestock herds.  

NAHLN is a partnership of Federal, state and university-associated animal disease diagnostic laboratories that provides ongoing animal disease surveillance. Because of its network structure, NAHLN labs are able to carry out testing from neighboring states and therefore meet the diagnostic needs of this specific disease outbreak and the National Milk Testing Strategy.  

More information about the NMTS and states conducting testing under the strategy can be found here

Findings from the NMTS to date 

As part of the National Milk Testing Strategy’s sampling of milk silos and bulk tank milk, APHIS has not detected any affected herds in new states without previous confirmed detections. States participating in the National Milk Testing Strategy are testing at a rate to provide a high level of confidence that an affected herd would be identified. This is a strong indicator that that the strategy is working as expected and underscores the need for continued monitoring and surveillance efforts at the bulk tank level.   

Many farms ship their milk to silos in neighboring states, which means that the National Milk Testing Strategy also captures information on herds outside the borders of currently enrolled states. As newly enrolled states work to align their testing with the parameters of the National Milk Testing Strategy, USDA continues to collect samples through other means as described above, which provides a strong basis of surveillance.  As the National Milk Testing Strategy expands to more states, USDA is able to more clearly determine where infection is, as well as where it is not. This allows us to better focus our efforts on eliminating the virus from the cattle herd. 

USDA strongly encourages herd owners to put in place strong, vigilant biosecurity practices and to participate in USDA’s available producer support programs, which help to cover the cost such as biosecurity programming, PPE for employees, and veterinary care. Producers can find more information at Financial Assistance | Animal and Plant Health Inspection Service, or at here Enhance Biosecurity | Animal and Plant Health Inspection Service, or your nearest USDA Farm Service Agency county office

HPAI Vaccines for Animals  

Since the 2014-2015 outbreak of HPAI in poultry, USDA has maintained the option to deploy vaccines in poultry, if needed, in an effort to leave no stone unturned in the fight against avian influenza. While deploying a vaccine for poultry would be difficult in practice and may have trade implications, in addition to uncertainty about its effectiveness, USDA has continued to support research and development in avian vaccines. In 2016, USDA created a national vaccine stockpile for use in commercial poultry, though the vaccines at that time were never deployed. Currently, due to the introduction of new HPAI strains, namely D1.1 from wild birds and persistent outbreaks among commercial poultry farms, USDA believes it is prudent to again pursue a stockpile that matches current outbreak strains.  

Current HPAI vaccines, licensed or unlicensed, do not meet the criteria for an ideal vaccine candidate. While there are U.S. licensed avian influenza vaccines for certain virus subtypes (H5N1, H5N3, and H5N9), none are fully matched to the more virulent strain of H5N1 found in the current outbreak. Novel or currently licensed vaccines are being updated to the current strain and/or evaluated for use in other animals, dependent upon the manufacturer’s interest. USDA intends soon to move forward with a contract for currently licensed vaccine to begin to establish a stockpile while continuing to evaluate vaccine strategy. This means USDA is not imminently implementing vaccination, but rather is continuing to move forward with planning and the purchase of vaccine or manufacturing capacity for vaccine. 

In dairy cattle, deployment of a successful vaccine candidate that is matched to the current strain is more feasible and more likely to be successful in stopping or slowing the virus’ spread.  USDA’s Center for Veterinary Biologics (CVB) released a notice earlier this year opening a pathway for interested parties to apply to conduct vaccine field safety trials in dairy cattle.  

To facilitate expedited vaccine development for bovines, USDA has consolidated several steps in the vaccine review process to allow them to occur in parallel. So far, at least seven candidates have been approved for field safety trials for vaccine candidates designed to protect dairy cows from H5N1. More information on the vaccine review process is available here. These steps are important to be sure vaccines developed are safe, are effective against the targeted virus, and do not lead to more shedding of the virus, among other considerations. USDA is ready and standing by to review additional submissions and initial results from the manufacturers as they are submitted.     

Note: This is order is in addition to the existing order issued April 24th (listed below this section)

On December 6, USDA issued a Federal Order requiring any person responsible for a dairy farm, bulk milk transporter, bulk milk transfer station, or dairy processing facility that sends or holds raw (unpasteurized) milk intended for pasteurization to allow APHIS or its cooperators to obtain raw milk in a quantity sufficient to test for HPAI virus. Additional information and resources related to this Federal Order and the related National Milk Testing Strategy are available at our website at website for more information: HPAI in Livestock | Animal and Plant Health Inspection Service.

Click the link below to vew the full federal order PDF.

2024-12-05 Federal Order

Below is an excerpt from this document from the USDA regarding these new requirements:

"The Animal and Plant Health Inspection Service (APHIS), United States Department of Agriculture (USDA), is issuing this Federal Order to prevent the spread of highly pathogenic avian influenza (HPAI). HPAI is a contagious viral disease of domestic poultry and wild birds. HPAI is deadly to domestic poultry and can wipe out entire flocks within a matter of days. HPAI is a threat to the poultry industry, animal health, human health, trade, and the economy worldwide. In the US, HPAI has now been detected in dairy cattle. 

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. 

For more information regarding this Federal Order go to HPAI Detections in Livestock Page."

See the following links for more detail:

Frequently Asked Questions
APHIS Requirements and Recommendations for State Animal Health Officials, Accredited Veterinarians and Producers
APHIS Page for HIPAI