Parasitic Fly Threat Re-emerges in U.S.

The U.S. Department of Agriculture recently confirmed three new cases of the New World screwworm, including infections in cows, goats, and dogs. This updates the nation’s total to five cases. This fly, which was declared eradicated in the 1960s, poses a serious threat to animals by laying eggs in open wounds or orifices. The emerging larvae then consume the host’s tissue.

At a news briefing, federal and Texas state officials announced the use of AI-driven technology to monitor screwworm populations. They are also training ranchers to identify infections in livestock and expanding facilities to generate and spread sterile flies, the main method to control screwworm populations.

Officials are also evaluating an emergency authorization for a new strain of genetically engineered flies that might speed up the production of sterile flies. Texas Governor Greg Abbott expressed confidence, stating, “We prevented and eradicated this pest before. We can do it again.”

The recent cases appear in a calf in La Salle County, Texas, a goat in Gillespie County, Texas, and a dog in Lea County, N.M. There is uncertainty if the dog was infected in the U.S., as officials noted its unclear travel history despite initial reports suggesting a recent presence in Mexico.

Previously, the first two infections were identified in calves in Zavala County, Texas. Nonetheless, Agriculture Secretary Brooke Rollins mentioned that the return of New World screwworm was not unexpected.