Arizona Dog Tests Positive for New World Screwworm

Arizona confirmed on Wednesday that a dog in Cochise County is the state's first animal diagnosed with New World screwworm. The canine was found on Monday with a wound on its back that state officials described as heavily infested with maggots. Laboratory testing verified the larvae as the New World screwworm species.

This finding places Arizona as the third U.S. state to report an animal infection. Texas and New Mexico previously identified such cases. The U.S. Department of Agriculture (USDA) stated that the risk to public health remains low. No human cases have been reported in the United States this year. The most recent human case involved a Maryland resident who returned from travel to El Salvador last year.

The Arizona Department of Agriculture (AZDA) is currently working with the attending veterinarian and the dog's owner to gather more details. The animal is under veterinary care. Dr. Ryan Wolker, the state veterinarian, said in a statement that officials have prepared for this possibility for a long while. He noted that extensive outreach and surveillance measures allow producers, veterinarians, and pet owners to recognize and report suspected cases quickly.

The USDA is responding by establishing an infested zone around the location. Federal agencies are increasing animal surveillance and coordinating with local partners. AZDA is requesting the release of sterile flies in the area to suppress the population. This technique aims to prevent the pest from becoming established in the region.

New World screwworm is a parasitic fly that feeds on live tissue. The larvae use sharp mouth hooks to screw themselves into the host, causing extensive damage. This infestation, known as myiasis, affects livestock, pets, and wildlife. In rare instances, it can infect humans. The Centers for Disease Control and Prevention (CDC) notes that people who travel to outbreak areas, spend time near livestock, sleep outdoors, or have open wounds face a higher risk.

Screwworm was eradicated in the United States for decades using a method that releases sterile male flies. These males mate with wild females, preventing reproduction. However, cases among livestock have migrated northward through the southern border over the past year. AZDA says the current response is designed to stop the spread before it becomes permanent.