Editor's note: This story was updated at 3:00 p.m. CST on Monday, June 8, 2026, to include a growing number of reported cases.
Federal officials have confirmed three additional cases of New World screwworm in Texas, bringing the state's total to five confirmed detections in less than a week.
The latest cases involve a calf in La Salle County, about 90 miles southwest of San Antonio and roughly 50 miles from the Mexican border; a dog identified in Andrews County in West Texas near the New Mexico border; and a goat in Gillespie County in the Texas Hill Country, according to the U.S. Department of Agriculture.
Officials said the dog came from a household in Lea County, New Mexico, and had recently been in Mexico. Investigators have not concluded that screwworm flies naturally spread to Andrews County, and the infestation may have occurred before the animal entered Texas.
Chad Cross, a professor at the Texas Tech University School of Veterinary Medicine, said the Andrews County case underscores concerns about the movement of animals across borders and state lines.
"We do not have guidelines in place to inspect companion animals largely when they're brought across borders," Cross told TPR's "The Source."
Dogs have been identified as hosts in Mexico and other countries where screwworm remains active, Cross said.
New World screwworm is a flesh-eating parasite that was eradicated from the United States in the 1960s. Female flies lay eggs in open wounds or body openings of warm-blooded animals. When the eggs hatch, the larvae burrow into living tissue, causing severe wounds that can be fatal if left untreated.
The pest primarily threatens cattle and other livestock but can also infest wildlife, pets and, in rare cases, people.
Officials say the concern is not the number of infected animals alone, but the potential for the fly to become established in Texas and spread rapidly. Texas is home to the nation's largest cattle industry, and an outbreak could cause significant economic damage.
USDA and the Texas Animal Health Commission said 75 personnel are actively responding on the ground, with additional support focused on diagnostics, logistics, surveillance and outreach. Officials have established quarantine zones around confirmed cases and are increasing trapping and monitoring efforts.
The agency also announced that sterile fly release operations will begin this week from Moore Air Base in Edinburg. Releasing millions of sterile flies is considered the primary tool for eradicating screwworm populations by preventing reproduction.
USDA Secretary Brooke Rollins visited Kerrville on Monday for a briefing on the state's screwworm response at the Knipling-Bushland U.S. Livestock Insects Research Laboratory. Rollins described the detections as an emergency while emphasizing that the nation's food supply remains safe.
"This does not affect the food supply system," Rollins said. "This is not a virus. It is not a disease. It is a pest and so we obviously are treating it as such, but the food supply system remains intact and couldn't be safer."
Ahead of the visit, Rollins announced that President Donald Trump had appointed San Antonio businessman and Texas A&M Regent John Bellinger as USDA's Senior Advisor for New World Screwworm Preparedness. Bellinger, a longtime cattle industry and food safety executive, will advise the agency as it expands efforts to contain and eradicate the pest.
"There's a lot of research going on. We hope it works. We hope we can come up with something, but the obvious is we need more sterile flies," Bellinger said.
Despite the heightened response from state and federal officials, awareness on the ground appeared limited when Texas Public Radio visited La Pryor, the town nearest the Zavala County ranch where one of the first Texas screwworm cases was confirmed last week. Some residents said they had seen reports about screwworm on social media. Others said they knew little about the parasite.
For ranchers in South Texas, the threat feels immediate. Christian Biedenharn, who ranches in La Salle County, said producers are closely monitoring their herds and want additional resources deployed quickly.
"We need those quarantine zones, and we actually have a methodology to treat them in terms of sterilization of those flies," Biedenharn told TPR. "We need funding and we need to be able to deploy those flies as fast as possible. We kind of need all-the-above strategies right now."
The United States currently relies on sterile screwworm flies produced in Panama and Mexico. A sterile fly production facility is under construction in South Texas but is not expected to be operational until next year.
In San Antonio, the city's Animal Care Services and Metropolitan Health District referred questions about screwworm preparedness and response efforts to state animal health officials.
As state and federal agencies lead the response, San Antonio Mayor Gina Ortiz Jones said the outbreak highlights the importance of maintaining the infrastructure needed to monitor and respond to emerging threats.
"It's instances like this that remind us why we need to have public faith in government institutions and invest in the infrastructure that allows us to monitor impacts not only to animals, but also to our economy," Ortiz Jones told TPR's "The Source."
USDA is urging livestock and pet owners to watch for draining wounds, maggots, unusual lesions or signs of discomfort and report suspected cases immediately to a veterinarian or animal health authorities.
"We need the partnership of animal owners across the region," USDA Under Secretary Dudley Hoskins said in a statement. "Please stay vigilant, check your animals closely, and report anything that looks suspicious."
Jerry Clayton, Kory Cook, and Joey Palacios contributed to this report.
