A deadly livestock parasite has slipped back into Texas from Mexico, and while Washington scrambles, ranchers are asking whether federal gatekeepers moved fast enough to protect the border in the first place.
Story Snapshot
- New World screwworm, eradicated from the United States for decades, is confirmed again in Texas cattle and additional cases are now appearing.[1][2][5]
- The Trump Administration and Governor Greg Abbott are rolling out quarantines, movement controls, and massive sterile-fly releases to stop the pest at the border.[1][2][5]
- Federal dashboards show more detections since the first June 3 Texas calf case, raising the stakes for U.S. beef and wildlife.[1][5]
- Experts say human risk remains low, but the economic and animal-welfare threat for producers is serious if the parasite takes hold again.[3]
What The New World Screwworm Threat Means For Texas Ranchers
The New World screwworm is not a worm at all but a parasitic fly whose larvae burrow into the living flesh of warm-blooded animals, including cattle, wildlife, and even pets.[2][4] United States Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS) confirmed on June 3, 2026, that a three-week-old calf in Zavala County, Texas, was infested, marking the first U.S. detection in decades.[1][2][4] Wildlife officials warn that untreated infestations can quickly become infected and kill affected animals, turning a single overlooked wound into a fatal event.[4]
New World screwworm had been officially eradicated from the United States by 1966, but it re-emerged in Central America and then moved north through Mexico after being detected there in November 2024.[3][5] Mexican detections have been confirmed within roughly 120 to 200 miles of the Texas border, illustrating how quickly a foreign animal pest can approach when border controls and international coordination falter. As the parasite advanced, federal authorities began releasing millions of sterile flies in a barrier zone, but those efforts did not fully prevent incursions into Texas herds.[1][3][5]
How The Trump Administration And Abbott Are Responding On The Ground
After confirming the Zavala County case, USDA established a 20-kilometer infested zone around the ranch and imposed quarantines, livestock-movement controls, and intensive surveillance in the area.[1][2][5] The agency accelerated targeted release of sterile New World screwworm flies using ground chambers on top of roughly four million sterile flies already being dropped aerially each week along the border region, aiming to collapse the breeding cycle.[1][3][5] Governor Greg Abbott declared a statewide disaster for Texas livestock and wildlife, ordered expanded surveillance, and coordinated closely with Texas Animal Health Commission and Texas Parks and Wildlife to push rapid reporting from producers.[4][5]
Even as USDA’s first announcement stressed that “to date, there have been no further detections,” its own live status dashboard quickly recorded additional confirmed cases in U.S. animals by June 8, undercutting any sense that this was a one-calf anomaly.[1][5] The dashboard explains that isolated detections outside the core dispersal area are not unexpected and are being addressed quickly, with suppression zones adjusted based on modeling and trap data.[5] This fast-changing picture highlights why ranchers do not trust early reassurances and instead look to hard numbers on confirmed cases, quarantine boundaries, and the scale of sterile-fly release operations along the Texas frontier.[1][2][5]
Balancing Real Animal Threats With Clear, Calm Risk For People
The Centers for Disease Control and Prevention reports that New World screwworm outbreaks in Central America and Mexico have produced substantial animal losses and at least one human infestation linked to travel, but emphasizes there is no immediate risk of locally acquired human infestation in the United States.[3][5] That human case in the U.S. was travel-associated, not the result of domestic transmission, and there have been no locally acquired infestations in people as of the latest federal update.[3][5] Federal health officials nonetheless urge anyone who suspects a screwworm wound to seek medical evaluation promptly so that isolated cases are identified and contained quickly.[3]
The state of Colorado has announced a new “Response Plan” to protect Colorado’s cattle industry from the New World Screwworm (NWS). https://t.co/9qTKSAW8Vp
— AVMA (American Veterinary Medical Association) (@AVMAvets) June 8, 2026
Veterinary and livestock groups are treating the parasite as a serious economic and animal-welfare threat, even if the human danger remains low.[2][4] The American Veterinary Medical Association describes how female flies lay eggs in open wounds, nostrils, or genital areas, and larvae then feed on living tissue rather than dead flesh, producing foul odor, rapid wound expansion, and potentially fatal infection if untreated. Texas A&M AgriLife Extension and the Texas Farm Bureau are urging ranchers to inspect animals daily, monitor newborns and breeding stock, aggressively treat open wounds, and immediately isolate and report any suspected cases to veterinarians, state animal health officials, or USDA.[2][4][5]
Sources:
[1] Web – New World Screwworm Cases Grow As Trump Admin, Abbott Vow to Fight …
[2] Web – Latest New World screwworm detection in Mexico prompts USDA to …
[3] Web – USDA Confirms New World Screwworm in Texas
[4] Web – The New World Screwworm in the United States: A Narrative Review …
[5] Web – New World Screwworm Information | Oklahoma State University