Tracking the deadly parasite threatening Texas livestock and wildlife -- the latest spread data, prevention efforts, and government response.
Texas animal health officials have imposed movement restrictions on parts of two Big Bend counties after screwworm was found in a horse near the Rio Grande — the first horse infested since the flesh-eating parasite returned to the United States in June.
A dog in Crockett County tested positive for New World screwworm on Aug. 31, and by the next afternoon the state veterinarian had drawn a new quarantine line around part of the county.
The Texas Animal Health Commission lifted New World screwworm movement restrictions on parts of five Texas counties on Aug. 31, the first zones released since the state began responding to the pest. Designated areas of Gillespie, Kerr, Kimble, La Salle and Webb counties were freed from the restrictions after months of coordinated surveillance and eradication work, according to an Aug. 31 news release from the commission.
Federal animal health officials lifted movement restrictions on livestock in part of New Mexico on Aug. 30, the first time any area of the United States has come out from under a screwworm control zone since the outbreak began in June.
Mexican cattle began crossing into the United States again on Aug. 24 for the first time since 2025, but not through Texas.
Federal animal health officials have confirmed a case of New World screwworm in a sheep in Val Verde County, the first detection reported anywhere in the United States since Aug. 5 and the first in that county since the outbreak began.
Texas Agriculture Commissioner Sid Miller praised the U.S. Food and Drug Administration's decision to issue an Emergency Use Authorization for Simparica TRIO to treat New World screwworm infestations in dogs and puppies, according to an Aug. 13 news release from the Texas Department of Agriculture.
The New World screwworm outbreak that produced 30 confirmed cases in June has slowed to one so far in August.
The U.S. tally of confirmed New World screwworm infestations rose to 45 with a domestic sheep in Terrell County confirmed August 5, according to the U.S. Department of Agriculture's Animal and Plant Health Inspection Service confirmed-detections dashboard.
The number of confirmed New World screwworm cases in the United States rose to 44 over the weekend, according to the U.S. Department of Agriculture's Animal and Plant Health Inspection Service, which tracks every confirmed detection on a public dashboard updated daily.
Eight weeks into the first New World screwworm outbreak on U.S. soil in decades, the numbers have gone quiet.
Texas Agriculture Commissioner Sid Miller praised a limited reopening of the U.S. border to cattle imports from Mexico, while warning that the federal response to the New World screwworm has not gone far enough to protect the nation's livestock industry.
A new infestation in a Sutton County goat, confirmed July 21, pushed the United States tally of New World screwworm to 42 cases — up from the 41 reported last week, when the parasite reached Starr County on the Rio Grande for the first time — but the more telling number this week is how few of those cases are still live.
New World screwworm has been confirmed in Starr County for the first time, carrying the outbreak into a Rio Grande border county and pushing the U.S. case count to 41.