Just days before the U.S.-Mexico port in Douglas, Ariz., is scheduled to reopen to livestock on Monday, Aug. 24, 2026, the Mexican state of Sonora has confirmed its first case of New World screwworm (NWS).
According to Reuters, “Mexico’s Sonora state has activated emergency surveillance, containment and control protocols following the detection of its first case of screwworm, Governor Alfonso Durazo said on Wednesday [Aug. 19, 2026].”
Sonora is just south of Arizona. According to KJZZ, a Phoenix radio station, the case was reported in a cow in the southern region of Sonora, about 10 miles from the border with the Mexican state of Chihuahua. Sonora’s Ministry of Agriculture (SAGARHPA) reports 360,000 sterile NWS flies have been released in the area around the state’s first case.
The Sonora detection was just days after a case was reported in Ciudad Juárez, Mexico. The canine is located 18 miles from the U.S. border. Juarez is located in the state of Chihuahua, which is currently reporting 75 active NWS cases. Juárez is the border city to El Paso, Texas.
Since the first NWS was found in the U.S. on June 3, USDA has reported 46 confirmed cases. Currently there are two active cases.
What Does This Mean for the Aug. 24 Reopening?
The USDA’s Animal and Plant Health Inspection Service (APHIS) previously announced a phased reopening of southern ports to livestock trade, beginning with the Agua Prieta-Douglas crossing on Monday, Aug. 24, 2026. Historically, Sonora and Chihuahua have been categorized as low-risk zones. However, the USDA has explicitly stated that the reopening schedule is flexible and will be paused if U.S. authorities identify an increased risk in either state.
The question is, will USDA move forward with opening the border on Monday, Aug. 24. Stay tuned to Drovers for the latest.
