Confirmation of the first case of a novel horse screw worm in America
On September 9, the first case of New World screwworm (NWS) in the 2026 outbreak was identified on the hind limb of a working farm horse in Presidio County, Texas. NWS is a dangerous parasite that can infect the wounds of horses and other warm-blooded animals. Since larvae feed on living tissue, even small cuts or wounds must be cleaned, protected, and carefully monitored until fully healed. For more information about NWS, you can view a previous USEF webinar here. Horse owners should check their horses daily for wounds, swelling, discharge, foul odor, or larvae. Pay special attention to small cuts, surgical sites, foals' navel areas, and moist areas like lips, nostrils, eyes, and genital areas. If you see larvae or any other abnormalities in a wound, contact your veterinarian immediately. Early reporting to animal health officials helps them respond faster with eradication tools like releasing sterile male flies in your area. The United States Equestrian Federation has protocols in place for licensed competition organizers and participants to reduce opportunities for the spread of these flies. These mandatory measures may include inspecting horses for wounds upon entry and continuing to monitor horses throughout the competition. Early identification of suspected cases and reporting them helps protect horses and competition venues from the threat of screwworm, including contamination and resulting quarantines. Remember that animal health officials in each state set policies for animals within that state as well as animals entering from states or geographic areas with screwworm cases; therefore, you should be aware of both your state's requirements and those of USEF. USEF protocols and links to state and federal resources are available at usef.org/screwworm. We encourage all horse owners to help protect their horses and the broader equine community by adhering to proper wound care, fly control, and biosecurity. Check horses daily, keep wounds clean and covered as directed by your veterinarian, use fly control products recommended by your veterinarian, and limit fly access with physical barriers like fly masks, sheets, and maintaining hygiene practices in the stable. Questions can be directed to the USEF Equine Health Team at equinehealth@usef.org or Dr. Katie Flynn at 859-225-6991. Source: Practical Horseman – Health