USDA Confirms Presence of New World Screwworm in the United States

The USDA reported on June 3 the first case of New World Screwworm (NWS) in cattle in the United States in south Texas.

NWS is a serious threat because larvae infest living tissue and cause rapidly progressive, potentially fatal myiasis (maggot infestation) in warm-blooded animals, including humans.

Horses are susceptible to NWS infestation, and this disease is a serious concern for all in the equine veterinary community and larger equine industry.

The AAEP New World Screwworm Working Group, chaired by Dr. Katie Flynn, has been monitoring the progression of this disease since 2025 and working directly with federal officials regarding education efforts for both veterinarians and the equine industry.

The NWS Working Group has prepared the following overview of the situation with advice for equine veterinarians:

Alert to Equine Practitioners: New World Screwworm Enters the United States

The AAEP Infectious Disease Committee is finalizing guidelines for the disease, and those will be released soon as an additional resource.

The AAEP and its working groups will continue to keep the AAEP membership and the equine industry informed with the latest resources and updates regarding the disease.

About AAEP

The American Association of Equine Practitioners, headquartered in Lexington, Ky., was founded in 1954 as a non-profit organization dedicated to the health and welfare of the horse. Currently, the AAEP reaches more than 5 million horse owners through its over 9,000 members worldwide and is actively involved in ethics adjudication, continuing education, publishing, and research.