The U.S. confirms its first human case of New World screwworm. What is it?

Updated August 25, 2025 at 11:08 AM MST

The U.S. has confirmed its first human case of the New World screwworm, a flesh-eating parasite whose northward creep from South America has put the country's cattle industry on high alert in recent months.

The Centers for Disease Control and Prevention (CDC), in coordination with the Maryland Department of Health, confirmed the case on Aug. 4 in a patient who had returned from travel to El Salvador, Department of Health and Human Services spokesperson Andrew Nixon told NPR on Monday.

"This is the first human case of travel-associated New World screwworm myiasis (parasitic infestation of fly larvae) from an outbreak-affected country identified in the United States," Nixon said. "Currently, the risk to public health in the United States from this