REDFIELD, Iowa (DTN) -- New World screwworm (NWS) has not entered the United States, but with the closest case 90 miles away in Mexico, livestock officials continue to be cautious.

"We prefer to look at it as prevention measures instead of treatment," said Julia Herman, beef cattle specialist veterinarian for the National Cattlemen's Beef Association. "Even though NWS is not contagious, it's considered a foreign animal disease since it is not currently found in the U.S."

Herman did stress the importance of reporting any suspect cases, as NWS is a reportable disease in all states and the sooner it is confirmed in an area, the faster animals can be treated and sterile NWS flies can be released to combat the problem.

NWS SITUATION IN MEXICO

More than 20,000 cases of NWS have been found in Mexico during this outbreak that dates back to November 2024, with 1,295 cases currently being considered active. The U.S. border has been closed to cattle, bison and equine since July 2025.

NEW DOMESTIC STERILE FLY FACILITY

Today, U.S. Secretary of Agriculture Brooke Rollins held a news conference in conjunction with the groundbreaking for USDA's domestic sterile fly production facility at the Moore Air Base in Edinburg, Texas.

"Breaking ground on this facility marks a major investment in safeguarding America's livestock and the producers who feed this nation. This puts NWS sterile fly production in American hands," said Rollins during a news conference at the Moore Air Base. "Last August we pledged to build an NWS sterile fly facility in the U.S. with the ultimate goal to never be in the situation again and to not worry about this devastating pest."

Rollins said a year ago, the models showed NWS would have moved into the U.S. by now, but it has not and keeping the pest out has been a huge undertaking for all involved. Since last July, USDA has monitored over 7,000 fly traps on the border and has collected over 51,000 fly specimens, with all being negative for NWS.

"Today, this is the groundbreaking which I think will eventually lead to the eradication forever of New World screwworm," she said. The facility is expected to be up and running by the end of 2026 and will initially produce 100 million sterile NWS flies during stage 1, with production rising to 300 million sterile flies by stage 2 at the end of 2028.

Sigrid Johannes, senior director of government affairs for NCBA, said the sterile fly technology is the most powerful tool to use against NWS. The current facility in Panama produces about 100 million sterile flies per week. A facility in Metapa, Mexico, was previously a fruit fly facility and has been converted to an NWS sterile fly facility and is expected to produce 60 million to 100 million sterile flies by July 2026.

"The facility in south Texas will help give us a high enough inventory of sterile flies to fight NWS and hopefully eradicate it," Johannes said. Further research is being completed to help sort the sterile flies that are being released to make the impact more effective in fighting the wild male flies.

If NWS is found in the U.S. it is not a food safety concern, but rather an animal welfare concern. There would also be immediate trade implications for live animals, according to Herman.

TREATMENT OPTIONS FOR PRODUCERS

Treatments have come a long way in the past year, according to Johannes. "We have four options for approved cattle treatments of NWS. Dectomax-CA1, Exzolt Cattle-CA1, Ivomec 1% Injection, and the most recently approved is F10 Antiseptic Wound Spray with Insecticide," she said. Dectomax-CA1 and Ivomec are injectible medicines, Exzolt Cattle-CA1 is a topical solution, and F10 is a topical spray. Johannes said producers should contact their herd veterinarian about what the best option is for their situation.

PLAYBOOK HELPS PLANNING AHEAD

The Screwworm Response Playbook is another resource for fighting NWS. The original draft was released in October 2025. The current draft was released by USDA's Animal and Plant Health Inspection Service on April 8.

"USDA continues to execute Secretary Rollins' five-pronged plan to keep NWS out of the United States," said USDA Under Secretary for Marketing and Regulatory Programs Dudley Hoskins, in a USDA news release. "While we are aggressively safeguarding American agriculture and working with Mexico to prevent further northward spread, we must also ensure our domestic response plans are ready for immediate activation. Strong coordination with states, producers, veterinarians, sportsmen, and other partners is essential to achieving that goal."

Johannes said the new playbook outlines how to deal with an infested zone, surveillance zone and fly surveillance zone in areas where the fly is found, and how to be able to continue movement of animals without choking the supply chain.

The playbook outlines science-based strategies for officials at the federal, state, and local levels with how to coordinate response operations, reduce spread and prevent NWS establishment, manage the pest in infested animals, implement surveillance and control measures, and support information flow all while maintaining continuity of business.

"We expect to have more information coming out soon about getting certified to inspect animals for NWS," Johannes said. "In the meantime, we would recommend all farms and ranches to get a premise identification number because that will be needed to move cattle."

Herman reminds producers to develop a biosecurity plan to protect their herd from this and other diseases. An enhanced biosecurity plan should be practical and consistent. She stressed the importance of keeping good records on all animals and to be willing to make changes when needed to protect the herd. "This (a biosecurity plan) is something we can do now, to help prevent a problem later," she said.

For more information, visit https://www.aphis.usda.gov/… and www.bqa.org/screwworm.

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

Follow her on social platform X @JennCattleGal

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