New Case of New World Screwworm in Texas

U.S. agriculture officials confirmed a new case of New World screwworm in Texas. This development has raised concerns about containment of the flesh-eating parasite. The screwworm, known for its larvae that feed on living tissue, was previously eradicated in the U.S. decades ago through a sterile-fly release program. Despite this effort, surveillance and response measures have increased in affected U.S. areas.

On Monday, Newsweek reached out to the U.S. Department of Agriculture (USDA) for further details via email.

The USDA’s screwworm rapid response account posted a confirmation of the new case on “X,” noting the detection in a goat. The statement on the post stated, “The case was identified in a castration site wound. NWS only infests open wounds—it does not affect healthy skin. This detection is approximately 180 miles west of the initial Texas detection and 74 miles west of the nearest previously confirmed case.”

Mexico has reported nearly 30,000 cases since November 2024, with 1,800 cases still active. In the U.S., there are 16 cases reported.

Current U.S. Cases

The USDA’s dashboard shows that U.S. cases include cattle, sheep, goats, and one dog. Monday’s case appeared in Terrell County, Texas, following another case confirmed on Sunday in Edwards County. New Mexico had one dog case, now inactive.

Screwworm detections in North and Central America have heightened concerns among ranchers and animal health experts. Response teams are intensifying inspections, outreach, and containment measures, including sterile insect techniques proven effective in suppressing screwworm populations. Authorities are urging livestock owners to report suspicious wounds.

Threat to Animals and Humans

New World screwworm poses threats to livestock, wildlife, pets, and rare human cases. Federal and state officials are identifying additional cases and monitoring animal movements to reduce further spread.

Understanding New World Screwworm

The U.S. Centers for Disease Control and Prevention explains that New World screwworms are flies that lay eggs in open wounds or body openings like eyes, genitals, nose, or mouth. The eggs hatch into maggots that consume the animal’s tissue.

History of Screwworm in the U.S.

Once widespread in the Southern U.S., New World screwworms caused major losses for livestock producers. Eradication was achieved through releasing sterile male flies, reaching zero cases by 1982.

Current Outbreaks

The current outbreak centers in parts of Mexico and Central America, with the screwworm spreading north. In the U.S., confirmed cases remain in Texas and New Mexico as of Monday.