USDA Mobilizes Aggressive Response After First Confirmed New World Screwworm Case in Texas
Rollins says detection is contained, food supply remains safe, and massive sterile fly campaign is underway
USDA Secretary Brooke Rollins sought to reassure livestock producers, veterinarians, state officials and consumers Thursday following the first confirmed U.S. detection of New World screwworm (NWS) in a three-week-old calf in South Texas, emphasizing that the pest has not become established in the United States and that an aggressive federal-state response is already underway.
Speaking during a lengthy USDA press briefing, Rollins outlined a broad containment strategy that includes quarantines, surveillance, sterile fly releases, federal-state incident command operations and enhanced border monitoring. She repeatedly stressed that the detection does not represent a food safety threat and said USDA has spent the last year preparing for precisely this scenario.
Immediate federal response and quarantine measures. Rollins said USDA and the Texas Animal Health Commission immediately established a unified incident command structure after confirmation of the case in a calf near La Pryor in Zavala County, Texas.
“We’ve established a 20-kilometer (12 mile) control area around the detection and are implementing quarantines, movement controls and surveillance in this area,” Rollins said.
Texas Animal Health Commission Executive Director Dr. Andy Dinges said Texas has established an infested zone roughly equivalent to a 12-mile radius around the detection site. Warm-blooded animals are currently prohibited from leaving the area unless inspected and permitted by animal health officials.
Dinges said investigators have found no evidence of recent animal movement onto or off the affected premises and no additional infested animals have been identified. “The infested calf is doing much better,” Dinges reported. “They looked at the cattle on the premises and didn’t find any other infested animals.”
Massive sterile fly deployment accelerates. A central component of the response remains the sterile insect technique that successfully eradicated New World screwworm from the United States decades ago. Rollins said USDA immediately deployed additional sterile fly ground-release chambers and is continuing aerial dispersal operations. “We’ve expedited the release of millions of sterile New World screwworm flies,” she said.
APHIS Screwworm Director Adm. Michael Schmoyer said approximately 4 million sterile flies per week are being released through ground operations and another 4 million per week through aerial dispersal around the affected area. Schmoyer emphasized that sterile fly releases remain the most effective eradication tool available and credited the strategy with slowing the pest’s northward advance through Mexico over the past year. “The suppressive effect has been effective,” Schmoyer said. “We just need more flies.”
How USDA prepared for this moment. Rollins devoted significant time to describing preparations undertaken since NWS began moving north through Central America and Mexico. According to Rollins, USDA expanded sterile fly production capacity, opened the Moore Air Base sterile fly dispersal facility in South Texas earlier this year, broke ground on a major production facility expected to generate up to 300 million sterile flies per week beginning in 2027, retrofitted facilities in Mexico, and deployed more than 8,000 surveillance traps along the U.S./Mexico border. She noted that USDA personnel examined more than 58,000 fly samples and over 19,000 wildlife specimens before the first positive detection. “All of those were negative until yesterday,” Rollins said.
Rollins argued those efforts bought valuable time. “All the models predicted that no matter what happened or what we did, that the New World screwworm would be on our side of the border last summer or early fall,” she said. “The team you see on the call today … got us that extra year to prepare for this moment.”
No food safety risk. Throughout the briefing, both federal and state officials repeatedly emphasized that New World screwworm is not a food safety threat. “This pest does not cause a food safety issue,” Rollins said. “The food is not compromised at all. This is not a disease. It is not a virus.” She explained that the parasite lays eggs in open wounds where larvae feed on living tissue. When detected and treated early, affected animals generally recover fully.
Dinges echoed that message. “This is not a food safety issue. This is a food production issue,” he said.
What producers should do immediately. Federal and state officials repeatedly stressed vigilance by livestock owners. Schmoyer quoted a Texas animal health official who often says, “The most important thing you can put on your animals are eyes.”
Both Schmoyer and Dinges urged producers to inspect livestock daily, pay close attention to wounds, cover and treat injuries promptly, and immediately report suspicious lesions or infestations. “If you see something, report it,” Dinges said.
Officials noted that screwworm infestations occur only when flies deposit eggs in or near wounds, making wound management a critical prevention tool.
Human health concerns remain limited. CDC officials participating in the call said the risk to humans in the United States remains low. Dr. Paul Cantey of CDC noted that more than 2,075 human infections and 10 deaths have been reported in the ongoing Central America and Mexico outbreak region. However, he emphasized that human risk in the United States would remain localized to areas where non-sterile flies are present.
“The risk of human infestation remains low in the United States,” Cantey said.
FDA approves multiple treatment options. FDA officials reported that twelve products are currently available through emergency authorization or conditional approval to treat or prevent New World screwworm infestations. Dr. Timothy Schell of FDA’s Center for Veterinary Medicine said the agency continues working with USDA and industry on additional treatment options, including potential feed-based products. “We know there is a very high interest and a high demand for a feed option, and we’re working very diligently to provide that option as soon as possible,” Schell said.
Border controls and Rollins’ criticism of past policies. Rollins linked the screwworm’s movement northward to both illegal cattle trafficking and broader border security issues. She noted that USDA closed livestock import ports along the Mexican border in May 2025 and said those restrictions remain in place indefinitely. “We will obviously keep the ports closed until further notice,” Rollins said. She argued the closure delayed the pest’s arrival into the United States by roughly a year.
Rollins also blamed “the illicit movement of cattle” and “open border policies” during previous years for helping facilitate the pest’s movement northward through Mexico. “We had to keep our livestock producers as safe as possible,” she said.
Economic stakes are enormous. Asked about a Texas A&M analysis estimating that a widespread Texas outbreak could cost producers $732 million annually and reduce state economic activity by more than $1 billion per year, Rollins acknowledged the severity of a worst-case scenario. However, she emphasized that those projections assumed a much broader infestation than what currently exists. “That was assuming that we were going to be battling a full infestation,” Rollins said. She argued today’s circumstances differ dramatically from the 1950s and 1960s eradication era because of modern surveillance systems, communications capabilities, sterile fly technology and coordinated response plans. “We’re not looking at that in this case,” she said.
USDA projects confidence but not complacency. The overarching message from USDA officials was one of cautious confidence. Schmoyer repeatedly noted that only one animal has been confirmed positive and that federal resources can be rapidly expanded if necessary.
Dinges stressed that Texas and USDA have spent more than a year preparing response plans for exactly this scenario.
Rollins concluded by promising continued transparency and frequent updates, including additional stakeholder calls and public communications through USDA and APHIS channels. “If we all work together and follow these treatment and movement restriction guidelines, there is no reason to believe that this incursion will result in any sort of establishment of the pest on our side of the border,” Rollins said.
The next several days of surveillance, trapping and epidemiological investigations will likely determine whether this remains an isolated detection or becomes a larger animal health challenge for the U.S. livestock industry.
