REDFIELD, Iowa (DTN) -- As the New World screwworm (NWS) has continued to spread north in Mexico, U.S. officials continue to do what it takes to fight the pest. On Monday, U.S. Secretary of Agriculture Brooke Rollins was in Edinburg, Texas, for the grand opening of the sterile fly dispersal facility at Moore Air Base.

"This sterile fly dispersal facility was a high priority project, and our team delivered it in record time. This new facility is a monumental achievement for our domestic preparedness efforts, but we are also diligently working to stop the spread of screwworm in Mexico, conduct extensive trapping and surveillance along the border, increase U.S. response capacity, and encourage innovative solutions," she said. "We will never stop fighting to protect American agriculture. USDA, through a whole-of-government approach, will continue to hold Mexico accountable to mitigating the spread of this dangerous pest."

The facility is part of USDA's five-pronged plan announced in June 2025 to help fight the pest. The facility will be capable of dispersing up to 100 million sterile flies per week. The most recent dispersal area includes part of Texas.

Stephen Diebel, Texas & Southwestern Cattle Raisers Association first vice president, said, "The value of equipping the U.S. to combat the threat of New World screwworm cannot be overstated. As Texans and cattle producers, we celebrate the opening of the sterile fly dispersal facility at Moore Airfield Base, strengthening our nation's ability to protect our cattle herd health, food security and economy which would suffer from any incursion of New World screwworm."

OFFICIAL TALKS TO CATTLEMEN

Adis Dijab, acting associate deputy administrator of USDA's Animal and Plant Health Inspection Service, told attendees at National Cattlemen's Beef Association CattleCon in Nashville, Tennessee, last week that it's important to be watching the active cases and inactive cases reported in Mexico. As of Feb. 7, Mexico had 15,122 total animal cases and 626 active animal cases.

"The active cases have just been identified and are being treated," Dijab said. "The inactive cases are considered that 15 days after treatment." He continued to explain the importance of stopping the movement of animals as they think most of the spread north has been due to illegal movement of cattle in Mexico.

Dijab continued to explain the importance of surveillance of animals, especially in areas of an established NWS presence. The top 10 conditions leading to myiasis, or infestation of the NWS larvae include umbilical area of a newborn, cuts, vampire bat bites, insect stings, wire cuts, new ear tag holes, dehorning, dog bites, peeling skin, or tick bites.

Besides the sterile fly dispersal facility, USDA plans to begin construction of an NWS sterile fly production facility at the same site. Currently, the only production facility is in Panama. The Texas production facility will ramp up production to eventually have an output of 300 million sterile NWS flies per week. In August 2025, USDA committed $750 million to build this facility.

"Also, there is a production facility in Mexico that should be ready hopefully by the end of August," Dijab added. "There they will produce 100 million sterile flies per week. Once we get to 500 million sterile flies produced per week, we hope to fight back the flies to the Darian Gap again."

The Darian Gap is a remote area with rough terrain on the Columbia-Panama border.

MEDICINES FOR TREATMENT AND PREVENTION

Three animal drug products have been authorized for the prevention and/or treatment of NWS in cattle.

"The threat of New World screwworm represents a growing concern to U.S. agriculture, potentially causing devastating economic losses for cattle producers that could reach hundreds of millions of dollars," Rick DeLuca, president of Merck Animal Health, said in a news release when his company received conditional approval from the Food and Drug Administration for Exzolt Cattle-CA1. This drug is also approved for treatment and control of cattle fever ticks.

Dan Tracy, veterinarian with Zoetis Beef Technical Services, told DTN that the conditional approval of Dectomax-CA1 is the first step in further approval. "We provided the information and it shows a level of efficacy for treatment and prevention of New World screwworm," he said. "Producers need to be vigilant in checking their cattle and identifying any health problems and have a relationship with their veterinarian. Dectomax-CA1 gives them another tool in their toolbox against screwworm."

Last week, Boehringer Ingelheim received Emergency Use Authorization from the FDA for the use of Ivomec (ivermectin) 1% Injection for the prevention of infestations caused by NWS in cattle. "Protecting the health and well-being of livestock is at the core of our mission," Steve Boren, vice president, U.S. Livestock, Boehringer Ingelheim, said in a news release. "We appreciate the proactive approach of the FDA and USDA in response to this emerging animal health threat and remain dedicated to supporting veterinarians, producers, and government as we work together to protect cattle herds."

SURVEILLANCE IS IMPORTANT

USDA continues to ask U.S. animal owners to check their pets and livestock for signs of NWS and report anything suspicious to their state animal health officials, USDA area vets and local veterinarians.

Adult screwworm flies are about the size of a common housefly with metallic green or blue body, orange eyes, and three dark stripes down the back. The maggots infect living warm-blooded animals. These animals, including humans, will need medical attention immediately.

The sterile insect technique has been used since 1936 to fight NWS. The flies are sterilized using ionizing radiation prior to release and a dye is added to be able to identify the sterile flies versus unsterile flies. Since the flies only mate once, no offspring are produced, thus drastically reducing the wild NWS population.

"We have put together a playbook for how to defend against NWS. We hope to have it out by the end of February, but we know we have to make changes as new things happen," Dijab said. A response strategy will help animal health officials have a plan, adapt and act across all phases of an outbreak.

Jennifer Carrico can be reached at jennifer.carrico@dtn.com

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