Gusano barrenador outbreak spreads across Mexican states, prompting sterilized‑fly releases and US cattle‑export pause

Mexico’s livestock parasite Cochliomyia hominivorax, known as the gusano barrenador, has been confirmed in multiple states. Chihuahua reported 14 cases in 11 municipalities, while Zacatecas recorded 206 cases, with Pinos municipality showing the highest incidence. Coahuila logged 189 cases, 37 of them active in 13 municipalities, and Tamaulipas confirmed eight canine infections treated by SENASICA clinics. The outbreak accelerated in Chihuahua, where active cases rose from 18 to 30 in a single day, a 67 % increase, spreading to 15 municipalities.

Authorities have intensified control measures. The federal SADER agency began releasing sterile male flies—about 20 million in Chihuahua and 2.5 million already released in Parral and Coronado—to disrupt the parasite’s reproductive cycle. Municipalities such as Meoqui are conducting free on‑site livestock and pet inspections under the “Médico visita mi establo” program. Veterinary officials warn that the parasite can affect cattle, horses, goats, dogs, cats, wildlife and humans when it exploits open wounds.

The United States Department of Agriculture announced that the Agua Prieta (Sonora) crossing will reopen for cattle shipments on 24 August, citing lower risk in Sonora and Chihuahua due to these sanitary measures, despite ongoing cases in other Mexican regions and recent detections in Texas and New Mexico.