REDFIELD, Iowa (DTN) -- New World screwworm (NWS) continues to move closer to crossing the U.S. border with the closest case being 25 miles away in a goat in the Mexican state of Coahuila, according to USDA.

U.S. Secretary of Agriculture Brooke Rollins held a press call Tuesday to communicate the status of NWS and the U.S. preparedness for the pest. Rollins said there has been some criticism of having the border closed to importing animals from Mexico, but had the border not been closed, it was estimated the NWS would have been in the U.S. by last summer.

"The NWS risk to humans is extremely low, but the threat to the U.S. livestock industry is real," Rollins said. Preventing the pest means animal movement must continue to be monitored. The U.S.-Mexico border has been closed since July 2025. Since NWS first became a threat to the U.S. in November 2024, she said, USDA has expanded border surveillance, trained dogs to guard checkpoints at the border, and increased the number of tick riders who look for the pest on wildlife at and near the border.

U.S. Under Secretary of Agriculture for Marketing and Regulatory Programs Dudley Hoskins said all the necessary government agencies are working together and using the five-pronged plan issued in June 2025 to combat the spread of NWS. "I want to stress NWS is not contagious from one animal to the next and it does not pose a food safety concern. It is spread by an NWS fly laying eggs in an open wound on an animal."

The spread of the pest is being combatted by the release of sterile NWS flies, which are expected to mate with the wild flies and since the flies only mate once, the pest would die and not reproduce. This method has been successful as far back as 1937 and was the method used to eradicate NWS in the U.S. in the 1950s and again in the isolated case in the Florida Keys in 2016.

MOST CASES SPREAD ON ANIMALS

Rear Admiral Michael Schmoyer, APHIS Associate Administrator and NWS Directorate, said most cases of NWS in Mexico have been through animal movement, as the actual fly doesn't seem to be moving very quickly. But once an infested animal moves to a new area, the larvae become flies and the spread continues. "All the most recent cases have been in the sterile fly dispersal area," he said.

Hoskins said while the spread has continued north in Mexico over the past 19 months and there is a larger plan that will need to be met before the border would be reopened to live-animal trade. "It's not about a specific state or region in Mexico but needs to be a system-wide approach (to eradicating NWS). Checkpoints are watching closely the animals that are moving, but not all animals are going through these checkpoints. There is still work to be done in Mexico to prevent the movement of NWS," he added.

Texas Animal Health Commission Executive Director Bud Dinges said the state continues to work with USDA on prevention measures, but they are prepared to react and respond immediately if and when the pest arrives in the U.S.

"All animal owners need to put your eyes on your animals. Monitor all wounds and contact a veterinarian immediately if you suspect New World screwworm," Dinges said. "It will take all of us working together to prevent the spread of this pest."

Overall, 8,000 fly traps have been set at and near the U.S. -Mexico border and 58,000 fly samples have been collected and all have been negative for NWS, according to Rollins.

"We have done everything we can on our side of the border to keep them out," she said. "The updated NWS playbook includes information on what to do if the pest gets to the U.S." Quarantines and stop movement will be put in place in the areas as well as releasing sterile flies to fight the wild NWS flies is part of the plan.

Currently, Panama has the only NWS sterile fly production facility, which produces around 100 million sterile flies per week. A facility in Metapa, Mexico, is expected to open this summer producing 60 to 100 million sterile flies per week. Construction continues at Moore Air Base in Edinburg, Texas, for a facility to produce 100 million sterile flies per week with an expected completion in November 2027 and then gradually ramp up to producing 300 million per week.

"We will not rest until New World screwworm is eradicated," concluded Rollins.

For more information on NWS, visit https://www.aphis.usda.gov/….

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

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