Ranchers and pet owners across parts of three Hill Country and South Texas counties can move animals without state permission again, after the Texas Animal Health Commission released the quarantine zone it drew around the first New World screwworm case found in Medina County.
Executive Director Lewis R. Dinges signed the release order on Sept. 16, lifting the restrictions the commission imposed on parts of Bandera, Medina and Uvalde counties on June 24. It is the sixth zone the state has released since the end of August, and it leaves restrictions in place in parts of 14 Texas counties.
New World screwworm is a parasitic fly whose larvae feed on the living tissue of warm-blooded animals, including livestock, pets, wildlife and, rarely, people. The United States eradicated it in 1966, and its return through Central America and Mexico has been the largest animal-health emergency Texas has faced in decades. When the commission establishes what it calls an infested zone, no warm-blooded animal may leave that area without an inspection and written authorization — a restriction that reaches cattle headed to market, horses headed to a show and dogs headed to a veterinarian.
The zone released on Sept. 16 was created a day after an infestation was confirmed in a cow in Medina County on June 23. In the order, Dinges wrote that based on “fly trapping and monitoring data, assessment of sterile fly dispersal, visual inspection of susceptible animals for myiasis, and the absence of additional NWS detections throughout the surveillance period following the last confirmed detection,” he “finds that sufficient evidence exists to demonstrate that surveillance conducted within the area identified for release satisfies the criteria for release from quarantine and movement restrictions.” The June 24 restrictions, he concluded, “have achieved their intended purpose.”
The tool doing most of that work is an old one. Sterile flies — males raised and irradiated so they cannot father offspring — are released over an infested area so that wild females mate without producing larvae, and the local population collapses. The order credits those releases, “together with animal inspections, treatment protocols, movement controls, and continued surveillance efforts,” with substantially reducing the risk of continuing infestation.
The release does not end every restriction. The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service, which concurred in the order, said in its announcement that “releasing infested zones removes NWS-related movement requirements for livestock and pets within certain areas,” but that “all interstate movement requirements and international export requirements will still apply.” Animals leaving Texas, or leaving the country, still face the federal rules.
Nor does it end the outbreak. Restrictions remain in parts of Brewster, Crockett, Edwards, Jeff Davis, Jim Hogg, Pecos, Presidio, Schleicher, Starr, Sutton, Terrell, Uvalde, Val Verde and Zapata counties, according to the notice the commission posts on its screwworm page, a list that matches the orders the agency has issued and not yet released. Zones are drawn around a detection site rather than along county lines, which is why Uvalde County appears both in the area released Sept. 16 and on the list of counties still partly restricted.
The federal detection dashboard, as of Sept. 16, counted 49 animal cases nationally, all in domestic animals, with two still active and 47 closed. It recorded no cases in wildlife or feral animals and no detections in fly traps — the two markers that would signal the parasite had established itself outside managed herds. The last confirmed animal detection was Sept. 9. The commission separately reports cases in 17 Texas counties across 39 premises.
The release is the state’s sixth since Aug. 31 and continues a steady contraction. The commission lifted restrictions in La Salle and Webb counties and in Gillespie, Kerr and Kimble counties on Aug. 31; in parts of Uvalde and Zavala counties and in Coke and Tom Green counties on Sept. 3; and modified another zone covering Kimble, Schleicher and Sutton counties on Sept. 4. The direction has not been uniform. The commission quarantined a new stretch of Crockett County on Sept. 2, and on Sept. 10 it drew a zone across Presidio and Jeff Davis counties after the outbreak’s first case in a horse, as The Texas Dispatch reported.
Dinges used the order to warn against reading a release as an all-clear. “Although quarantine and movement restrictions have been released from areas previously within the infested zone,” he wrote, “continued vigilance remains essential to prevent the reintroduction or reestablishment of NWS in previously impacted areas.” Animal owners, he added, should keep watching for wounds and report suspected cases.
Producers in Schleicher County, which remains under restriction, are scheduled to meet with animal health officials in Eldorado on Sept. 21.