First U.S. Human Case of Travel-Associated New World Screwworm Confirmed

August 25, 2025 – The U.S. Department of Health and Human Services (HHS) has confirmed the nation’s first human case of travel-associated New World screwworm, a flesh-eating parasite, in a patient who recently returned from El Salvador. The case was officially verified by the Centers for Disease Control and Prevention (CDC) on August 4 and investigated in coordination with the Maryland Department of Health.

“The risk to public health in the United States from this introduction is very low,” HHS spokesman Andrew G. Nixon said.

The parasite, which feeds on living tissue, has long been a concern in Central America and southern Mexico. While initial reports linked the case to travel from Guatemala, HHS did not clarify the conflicting accounts. Despite the discrepancy, officials emphasized that the risk to public health in the U.S. remains low, and no animal infections have been reported in 2025.

The confirmation has sparked concern among cattle ranchers and livestock industries, especially as screwworm continues its northward spread. The U.S. Department of Agriculture recently announced plans to build a sterile fly facility in Texas, aiming to prevent a potential outbreak that could cost the state’s cattle industry up to $1.8 billion.

Veterinarians and industry leaders criticized the lack of early transparency from the CDC, learning of the case through unofficial channels before formal confirmation.