The United States confirmed its first case of New World screwworm in Arizona, making it the third state with detections in the current outbreak, after Texas and New Mexico. The finding comes as the country continues gradually reopening border crossings to Mexican cattle.
The US Department of Agriculture (USDA) reported on October 28 that the parasite had been identified in a dog in Cochise County, which borders Mexico. A veterinarian examined the animal on Monday, October 26, and found a wound on its back heavily infested with larvae. The case was confirmed by the USDA’s National Veterinary Services Laboratories in Iowa.
The detection occurred near areas where cases had already been reported. On October 23, New Mexico authorities confirmed an infestation in a calf in Hidalgo County, which adjoins Cochise County. However, the published information does not allow the distance between the affected animals to be determined or an epidemiological link to be established.
In response to the Arizona case, authorities announced a 20-kilometer infested zone around the detection site, animal movement controls, increased surveillance and fly trapping, along with releases of sterile flies to interrupt their reproductive cycle. The dog remains under veterinary care, and the investigation is ongoing.
Cochise County is home to the Douglas border crossing, which reopened to Mexican cattle on August 24. Santa Teresa followed on September 24 and Columbus on October 26, both in New Mexico. APHIS maintains November 30 as the planned date for reopening the Nogales crossing in Arizona to Mexican cattle, subject to animal health conditions and the readiness of facilities and inspection procedures.
