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 New World screwworm outbreak in Texas widened as federal regulatory officials confirmed three additional cases far beyond the original South Texas containment zone and announced an escalated, multi-agency response.
Texas Agriculture Commissioner Sid Miller responded to the additional New World screwworm detection by demanding the immediate federal deployment of a specialized fly suppression system.
The international fallout from recent New World screwworm detections in South Texas escalated as the Canadian government moved to restrict imports of Texas livestock, drawing sharp pushback from state officials.
Governor Greg Abbott signed an updated statewide disaster declaration authorizing the use of all available state resources to eradicate the New World screwworm fly.
The US Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) confirmed on June 3, 2026 the detection of a New World screwworm (NWS) in a bovine in Zavala County, Texas — the first detection of the pest in the United States in decades.
The U.S Department of Agriculture confirmed the first domestic case of the New World screwworm in South Texas after a local lawmaker urged state action on the pest. According to a June 3 announcement and media call by USDA Secretary Brooke Rollins, testing on a livestock sample from La Pryor in Zavala County confirmed the first active infestation in the United States.
State Representative Don McLaughlin (R-Uvalde) issued an urgent call to action following reports that the New World Screwworm (NWS) has been detected one mile from the Texas border.
Governor Greg Abbott issued a disaster declaration for 44 Texas counties to prevent the spread of the New World screwworm fly.
Texas Agriculture Commissioner Sid Miller has called for increased animal surveillance after new cases of New World screwworm were confirmed in Tamaulipas, a Mexican border state.