US Records First Human Case of Flesh-Eating Screwworm

Health authorities in the United States have confirmed the country’s first-ever human infection with the New World screwworm — a parasitic fly whose larvae consume living flesh. The case was detected in a Maryland resident who had recently returned from El Salvador, where an outbreak is currently active.

According to the U.S. Centers for Disease Control and Prevention (CDC), the patient developed symptoms shortly after returning and was officially diagnosed on August 4, 2025.

“Screwworm larvae feed directly on living tissue, posing a severe and potentially life-threatening risk if untreated,” CDC Director Dr. Rochelle Walensky explained. She stressed that while human infections are exceptionally rare, anyone showing symptoms after travel should seek urgent medical care.

The U.S. Department of Health and Human Services (HHS) confirmed the case on August 24, 2025, and noted that federal officials are working closely with Central American health agencies to monitor travel-related risks. “We are treating this with utmost seriousness to ensure no further spread,” said HHS spokesperson Dr. Anthony Fauci.

Although screwworm infestations are far more common in livestock, where they can wipe out herds, experts warn that even isolated human cases are dangerous.

“The larvae can tunnel deep into healthy tissue, creating severe wounds that are extremely difficult to heal,” explained Dr. Jose Ortega, senior veterinary official at the U.S. Department of Agriculture (USDA). “While infections in humans are rare, in cattle they can cause losses running into billions of dollars.”

To contain the threat, the USDA is building a sterile fly production facility in Texas and has temporarily suspended cattle imports from Mexico. Mexico, in turn, is ramping up its sterile fly programs as Panama’s facility struggles to meet the demands of the expanding outbreak moving north from Central America.

So far, no cases have been identified in U.S. livestock this year. However, health experts caution that the Maryland infection underscores the importance of vigilance.

“Rapid diagnosis and treatment are vital to protect both human health and agriculture,” Walensky reiterated.