Early in July 2025, the USDA issued an immediate suspension of all livestock imports—including horses—from Mexican border ports following a confirmed detection of New World screwworm (NWS) in Ixhuatlán de Madero, Veracruz, approximately 370 miles south of the U.S. border and 160 miles north of Mexico’s sterile fly buffer zone.
What is New World Screwworm?
NWS is a parasitic fly whose larvae infest live tissue in wounds—posing a severe threat to horses, cattle, wildlife, pets, and even humans. Though eradicated in the U.S. by the 1960s, it has re-emerged after migrating from South America, crossing the Darién Gap into Central America and beyond.
| Date | Event |
|---|---|
| May 2025 | USDA halts live-horse imports from Mexico following early screwworm detections in Oaxaca and Veracruz. |
| June 2 & 16 | USDA audits screwworm eradication efforts in Mexico. |
| June 18 | USDA announces $8.5M sterile-fly facility in Texas and $21M upgrade to Mexico's capacity. |
| July 7 | Phased reopening begins at Douglas, AZ, with 7-day quarantine protocols. |
| July 9 | New NWS detection in Veracruz forces full suspension of live equine imports. |
Impact on the Equine Community
Trade interruption
All horse imports from Mexico are suspended until USDA confirms containment of NWS.
New import protocols
Reopening plans require 7-day quarantine, vet screening, and documentation at select border crossings (e.g., Douglas, AZ; Santa Teresa, NM).
Heightened biosecurity
Domestic horse transport within the U.S. will see enhanced inspection and monitoring for screwworm larvae or intermediate fly species.
How to Protect Your Herd
- Monitor USDA APHIS and EDCC for regular updates on port reopening and disease alerts.
- Inspect horses frequently for maggot-infested wounds or signs of screwworm myiasis. Report findings to your veterinarian immediately.
- Restrict cross-border transport and maintain biosecurity protocols on your property.
With rapid investments in sterile-fly programs and surveillance, USDA and its partners aim to control the spread of NWS before the outbreak reaches U.S. livestock. Reopenings will remain on hold until containment is verified. Horse owners and transporters are urged to stay alert and informed.
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