New World Screwworm Confirmed in Texas and New Mexico Horses
Edited Press Release Courtesy United States Equestrian Federation
The USDA has confirmed a case of New World Screwworm (NWS) in a leg wound on a working ranch horse in Grant County, New Mexico. This is the second confirmed horse case in the United States as part of the current incursion.
A map showing the infested zone related to this case is available here, and additional guidance from New Mexico animal health officials is available here.
On September 9, 2026, the first equine case of New World Screwworm as part of the 2026 incursion was detected on a hind limb of a working ranch horse in Presidio County, Texas.
NWS is a serious parasite that can infest wounds in horses and other warm-blooded animals. Because the larvae feed on living tissue, even small cuts or sores should be cleaned, protected, and checked closely until they are fully healed.
US Equestrian continues to monitor the progression of NWS in the United States and reminds you that fly migration and NWS protocols could change repeatedly in the coming weeks and months.
US Equestrian has protocols in place for licensed competition organizers and participants to reduce the opportunities for the fly to spread— both for those conducting events in infested states and those with horses shipping in from infested states or zones. Required steps may include checking horses for wounds when they arrive and continuing to monitor horses during the competition. Finding and reporting suspect cases early helps protect horses and competition grounds from screwworm threats, including infestation and resulting quarantines.
Remember that state animal health officials set policy for animals in their state, as well as animals coming in from states or geographic zones with screwworm cases, so you should remain aware of your state’s requirements as well as those of the Federation. You can find USEF protocols and links to state and federal resources at usef.org/screwworm.
Horse owners should inspect their horses every day for wounds, swelling, drainage, foul odor, or maggots. Pay close attention to small cuts, surgical sites, the umbilical area of foals, and moist areas such as the lips, nostrils, eyes, and genital areas. If you see maggots or anything unusual in a wound, contact your veterinarian right away. Early reporting helps animal health officials respond quickly with eradication tools like sterile fly release in your area.
More information on NWS for horse owners and competition managers can be found at usef.org/screwworm and on the dedicated USEF Equine Health Facebook page.
Learn more about NWS here: https://blog.ponyclub.org/2025/09/29/new-world-screwworm-bulletin/
USPC National Office
The United States Pony Clubs, Inc. (USPC or Pony Club) is the largest equestrian educational organization in North America. Started in 1954, the organization has developed curriculum that teaches safe riding skills and the care of horses through mounted and unmounted lessons. Through Pony Club, members have fun with horses and make lifelong friends while they develop skills, habits, and values that extend well beyond the barn and last a lifetime. Many members apply what they have learned in the USPC program successfully in their careers, educational and volunteer opportunities, and other life pursuits.
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