AKC warns active dogs face screwworm risk from small wounds

USDA APHIS confirmed New World screwworm in a bovine in Zavala County, Texas, on June 3 and added two more cases on June 8, including a dog in Andrews County, Texas. An American Kennel Club health advisory on June 24 warned that even a small wound can become an entry point.

Female screwworm flies are drawn to wounds, where they can lay hundreds of eggs at the edge of the injury, and the larvae can begin feeding within about 12 hours. The parasite is not a worm at all, but the larval stage of a fly that feeds on live tissue and burrows deeper as it goes, enlarging the wound and raising the risk of secondary bacterial infection and more widespread damage.

The Andrews County dog sample was submitted by a veterinarian, and the dog had recently been in Mexico. New World screwworm affects livestock, pets, wildlife, and less commonly people and birds. The current risk to people in the United States remains very low, and no human infestations acquired in the U.S. have been reported.

For active-dog households, any scratch, tick bite, hot spot, surgical incision, skin fold, or wound around a body opening deserves fast attention after travel, hiking, field work, boarding, or contact with livestock. Larvae can start feeding within hours.

USDA has created a dedicated New World Screwworm Directorate within APHIS, all southern ports of entry are currently closed to livestock trade, and federal and state partners in Texas are conducting surveillance and epidemiological investigations in the infested zone. The parasite was eradicated from the United States in 1966 through sterile insect technique, with female flies mating only once, which is why sterile male releases remain the core control tool. USDA and Panama’s Ministry of Agricultural Development jointly run the only active sterile fly production plant in North America through COPEG, and a new facility opened in Metapa, Mexico, on June 27.