Texas Gov. Greg Abbott has issued a disaster declaration for Zavala and Uvalde counties and authorized the use of all available state resources following confirmed detections of New World screwworm in South Texas.
State officials confirmed the first Texas case since the 1960s on June 3 in a three-week-old calf with an umbilical lesion in Zavala County, The Dallas Express reported. Additional detections were reported on June 5 and June 7 in young calves in Zavala and La Salle counties.
“I am issuing an updated statewide disaster declaration to make two things very clear,” Abbott said. “First, I authorize the use of all available resources of state government to respond to this disaster and reassign resources from across the state as needed to address NWS. Second, I am making all state personnel available to accelerate the movement of sterile flies into Texas and the construction of the new sterile screwworm production facility in Edinburg. We have eradicated this pest before, and we will do it again.”
Abbott received a briefing from officials with the Texas Animal Health Commission, Texas Parks and Wildlife Department, the U.S. Department of Agriculture, and other state and federal partners coordinating the response.
Despite its name, the New World screwworm is not a worm but the larval stage of a parasitic fly. The larvae feed on the living tissue of warm-blooded animals, including livestock, wildlife, pets, and, in rare cases, humans. Untreated infestations can cause severe injury or death.
The Texas Animal Health Commission has established quarantine zones in portions of La Salle, Uvalde, Webb, and Zavala counties. Under current orders, warm-blooded animals cannot be moved out of affected zones without authorization and inspection by animal health officials.
Federal and state agencies are using the sterile insect technique, a method credited with eliminating the pest from the United States in 1966. The process involves releasing sterile male flies that mate with wild females, which mate only once during their lifetime. Because the resulting eggs are nonviable, the population declines naturally over time.
USDA officials said sterile fly dispersal operations began on June 4. The agency is releasing 2 million sterile flies twice weekly through aerial operations and shipping an additional 4 million sterile flies each week for ground-based releases in and around affected areas.
“USDA has responded expediently with respect to this second detection, demonstrating our utmost preparedness. This second detection is within the established movement control zone and enhanced sterile insect dispersal area,” Dudley Hoskins, USDA undersecretary for marketing and regulatory programs, said in a news release.
“Many models projected this pest would reach the United States last year, but thanks to USDA’s phenomenal work and our cooperation with state, federal, and industry partners, we’ve held it off until now — when we are far more prepared to respond. USDA has not wasted any time in this fight, we have defeated New World screwworm before, and we will do it again.”
The USDA has also deployed veterinary specialists, diagnostic personnel, and mobile response trailers to Texas. Treatment supplies have been relocated to the state through the National Veterinary Stockpile, and emergency use authorizations have been issued for several treatment options covering livestock, wildlife, and other affected species.
Officials emphasized that the U.S. food supply remains safe. According to the USDA, screwworms do not infest meat, fruits, vegetables, or other food products, and any affected animal would be identified during federal inspection processes before entering commerce.
The current outbreak follows a steady northward spread of New World screwworm through Central America and Mexico in recent years. The pest was detected in southern Mexico in late 2024 after expanding through countries including Costa Rica, Nicaragua, Honduras, Guatemala, Belize and El Salvador.
Texas officials are urging livestock producers, veterinarians and pet owners to inspect animals daily for wounds, unusual lesions, maggots or signs of discomfort. Newborn animals, which may have healing umbilical wounds, are considered especially vulnerable.
State officials also asked Texans to promptly report suspected cases and avoid moving affected animals. Wildlife infestations should be reported to Texas Parks and Wildlife Department officials.
“Protecting Texas livestock, wildlife, and pets requires vigilance from every Texan,” Abbott said.
Officials stressed that early detection and treatment can effectively address infestations, while ongoing surveillance, quarantines, and sterile fly releases help eliminate the pest from affected areas.
