Full Breakdown
First U.S. Horse Infected with New World Screwworm Detected in Texas
By Drooid · · How we work
Core Event
On September 10, the U.S. Department of Agriculture confirmed that a working ranch horse in Presidio County, Texas, near the Mexican border was infected with the New World screwworm. The Texas Animal Health Commission immediately issued an order restricting the movement of warm-blooded animals outside designated “infested” zones in Presidio and Jeff Davis counties.
Background & Context
The New World screwworm, a flesh-eating fly larva, was declared eradicated in the United States in the 1960s after a nationwide campaign. Since then, the parasite has reappeared in Mexico and, earlier this year, was found on a calf in Zavala County, Texas, in June. The resurgence has prompted renewed control measures, including a sterile-fly dispersal facility launched in Edinburg during the Trump administration to reduce the pest’s reproductive capacity.
Official Statements & Responses
The Texas Animal Health Commission’s order aims to prevent further spread by limiting animal transport from the infested zones. The U.S. Equestrian Federation (referred to as the U.S. Equestrian Foundation in a separate statement) urged horse owners to inspect wounds daily, maintain fly control, and practice biosecurity. Governor Greg Abbott declared a disaster proclamation in June, mobilizing state resources to address the growing screwworm presence.
Data & Statistics
- This is the first documented equine case of New World screwworm in the United States.
- The USDA reports 49 U.S. cases this year, all in Texas except one dog case in New Mexico.
- Experts estimate that a widespread outbreak could cost Texas ranchers up to $1.8 billion.
- Historical outbreaks in the mid-20th century killed thousands of livestock before eradication.
What’s Next
State and federal agencies continue surveillance and containment efforts across the designated zones. Ongoing monitoring of livestock and wildlife, combined with the sterile-fly program, will determine whether the parasite can be suppressed before it expands further into the United States.
