Ag News
Mexico confirms case of New World Screwworm near U.S. border
Posted on Sep 24, 2025 at 13:05 PM
On Sept. 21, Mexico’s National Service of Agro-Alimentary Health, Safety, and Quality (SENASICA) confirmed a new case of New World screwworm (NWS) in Sabinas Hidalgo, located in the state of Nuevo León, less than 70 miles from the U.S.-Mexico border.
This is now the northernmost detection of NWS during this outbreak, and the one most threatening to the American cattle and livestock industry. Sabinas Hidalgo is located near the major highway from Monterrey, Nuevo Leon, to Laredo, Texas, which is one of the most heavily trafficked commercial thoroughfares in the world.
The previous northernmost detection was reported on July 9 in Veracruz, approximately 370 miles farther south. Preliminary reports from SENASICA indicate that the affected animal—an 8-month-old cow—had recently been moved to a certified feedlot in Nuevo León from a region in southern Mexico with known active NWS cases. The potential link to animal movement underscores the non-negotiable need for Mexico to fully implement and comply with the U.S.–Mexico Joint Action Plan for NWS in Mexico.
Currently, U.S. ports remain closed to imports of cattle, bison, and horses from Mexico.
Since July, USDA alongside Mexico, has been actively monitoring nearly 8,000 traps across Texas, Arizona, and New Mexico. To date, more than 13,000 screening samples have been submitted, with no NWS flies detected. USDA is analyzing all new information related to the recent case in Nuevo León and will pursue all options to release sterile flies in this region as necessary.
NWS maggots can infest livestock and other warm-blooded animals, including people. They most often enter an animal through an open wound and feed on the animal’s living flesh.
USDA urges residents on the southern border to check their pets and livestock for signs of NWS. Look for draining or enlarging wounds and signs of discomfort. Also look for screwworm larvae (maggots) and eggs in or around body openings, such as the nose, ears, and genitalia or the navel of newborn animals. If you suspect your animal is infected with screwworm, contact your state animal health official or USDA area veterinarian immediately.
While not common in people, if you notice a suspicious lesion on your body or suspect you may have contracted screwworm, seek immediate medical attention.
Learn more about NWS on the APHIS website.
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