New World Screwworm detected in Mexican sheep near US border

A six‑month‑old sheep in Coahuila, Mexico, was found infested with the New World Screwworm, a parasitic fly that can kill warm‑blooded animals. The infestation was located about 50 km (31 miles) from the United States border, the closest an outbreak has come to the U.S. during the current episode.

U.S. officials warn that if the pest spreads north, it could exacerbate an already depleted cattle herd, push beef prices higher and cause up to $1.8 billion in damage to Texas, the nation’s largest cattle‑producing state. The USDA and Mexico’s agriculture ministry have been deploying sterile‑fly release programs, but the facilities are not yet operational.

The detection heightens concern for American cattle producers, who have faced record beef prices and a herd at its lowest level in 75 years. Federal authorities have blocked cattle imports from Mexico for over a year to keep the screwworm south of the border.