The U.S. Department of Health and Human Services (HHS), in coordination with the Centers for Disease Control and Prevention (CDC), has confirmed the nation’s first human case of New World screwworm, a parasitic fly whose larvae feed on living tissue. The case was identified in a Maryland resident who had recently returned from El Salvador, where an outbreak is currently underway.
“This is a rare but serious infection,” said CDC Director Dr. Rochelle Walensky. “Screwworm larvae literally consume living flesh, and if left untreated, can lead to life-threatening complications. Early detection and treatment are critical.”
The patient began showing symptoms shortly after returning to the U.S. and was diagnosed on August 4, 2025. The HHS officially confirmed the case on August 24, emphasizing that federal and state health authorities are actively monitoring travel-related risks and collaborating with Central American health agencies to contain the spread.
Screwworms are parasitic flies that lay eggs in wounds on warm-blooded animals. Upon hatching, the larvae burrow into living tissue, causing severe damage. While more common in livestock, human infections—though rare—can be extremely dangerous.
Dr. Jose Ortega, senior veterinary official at the USDA, warned, “For cattle, screwworms can devastate entire herds. For humans, even a single case demands urgent attention.”
To mitigate risk, the USDA is constructing a sterile fly production facility in Texas and has temporarily halted cattle imports from Mexico. These measures aim to prevent further spread as the outbreak advances northward from Central America.
“No cases have been reported in U.S. livestock this year,” said HHS spokesperson Dr. Anthony Fauci, “but this human infection underscores the need for vigilance and swift action.”