Federal and state animal health officials are intensifying surveillance and containment efforts after multiple cases of New World screwworm were confirmed in livestock across Texas, prompting quarantine measures and movement restrictions in affected areas.
According to federal authorities, six cases of New World screwworm have been confirmed in cattle and goats across four Texas counties since early June. The detections were reported to the U.S. Department of Agriculture and involve animals in Zavala, La Salle, Gillespie, and Edwards counties. The findings have renewed concerns about the return of a pest that was eradicated from the United States decades ago.
Officials also clarified details surrounding a seventh case that was initially reported as a Texas infection. The case involved a dog that was first listed in Andrews County. Following an epidemiological investigation, authorities determined the animal actually resides in neighboring Lea County, New Mexico. As a result, the case has been reclassified as New Mexico’s first confirmed detection of New World screwworm.
Health officials explained that the confusion stemmed from the fact that the veterinarian who submitted the samples is based in Texas. Early information also indicated the dog had recently traveled to Mexico, where the parasite remains present.
In response to the growing number of detections, a quarantine remains in effect across portions of 10 Texas counties that have been designated as part of an established New World Screwworm Infested Zone. The affected counties include Edwards, Gillespie, Kerr, Kimble, La Salle, Sutton, Uvalde, Val Verde, Webb, and Zavala.
The Texas Animal Health Commission has implemented movement restrictions for warm-blooded animals within the quarantine area. Livestock owners seeking to move animals outside the designated zone must first obtain authorization from state officials. Animals must undergo inspection, and a movement certificate documenting identification and treatment measures must accompany them during transport.
State leaders have also stepped up emergency response efforts. Gov. Greg Abbott recently activated the Texas State Emergency Operations Center to coordinate resources and support containment activities. The move reflects growing concern over the potential impact of the parasite on livestock operations, wildlife populations, and agricultural producers throughout the region.
The Texas Parks and Wildlife Department has indicated that situation reports will continue to be updated daily as new detections are identified and investigations proceed.
The New World screwworm is considered one of the most destructive livestock pests in the Western Hemisphere. Unlike many fly species that feed on dead tissue, New World screwworm larvae infest and consume living tissue in warm-blooded animals. The parasite can affect cattle, goats, sheep, wildlife, pets, and, in rare circumstances, humans.
Adult flies are recognizable by their metallic blue bodies, orange eyes, yellow faces, and distinctive stripes running along their backs. Female flies deposit eggs in open wounds or other vulnerable areas on animals. Once the eggs hatch, larvae burrow into living tissue, causing painful and potentially severe infections if left untreated.
State agencies are dividing responsibilities based on the type of case involved. The Texas Animal Health Commission is overseeing livestock-related investigations and response measures, while the Texas Department of State Health Services is responsible for monitoring any human infestations.
Public health officials continue to emphasize that the overall risk to humans remains low. However, people living in or traveling to areas where the fly is present should take precautions to reduce the risk of exposure. Individuals who work outdoors, ranchers, animal handlers, people with open wounds, and those with certain medical conditions may face increased risk.
Health experts recommend keeping wounds clean and covered, sleeping indoors or in screened areas when possible, wearing long sleeves and pants, and using approved insect repellents. Clothing and outdoor gear can also be treated with permethrin-based products to provide additional protection.
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