First U.S. Case of Travel-Related Human Screwworm Linked to Central America Outbreak Confirmed

Published: Monday, August 25, 2025 at 8:59 am

First U.S. Human Screwworm Case Confirmed, Linked to Central America

The U.S. Department of Health and Human Services (HHS) has confirmed the first U.S. human case of travel-related New World screwworm, a flesh-eating parasite. The case, confirmed on August 4th by the Maryland Department of Health and the U.S. Centers for Disease Control and Prevention (CDC), involves an individual who recently returned from El Salvador.

The confirmation comes amid an ongoing outbreak of screwworms in Central America and southern Mexico. The HHS has stated that the risk to public health in the U.S. is low. However, conflicting information from government and industry sources regarding the origin of the case has raised concerns among cattle ranchers, beef producers, and livestock traders.

Screwworms are parasitic flies whose larvae burrow into the flesh of warm-blooded animals, including humans. Infestations can be fatal if left untreated. The U.S. Department of Agriculture (USDA) estimates that a screwworm outbreak could cost the U.S. cattle industry approximately $1.8 billion due to livestock fatalities, labor, and medication expenses.

The USDA is taking action to combat the pest, including plans to construct a sterile fly facility in Texas. Mexico has also initiated efforts, including building a sterile fly production facility. The U.S. has largely halted imports of cattle from Mexico to prevent the spread of the parasite.

BNN's Perspective: The confirmation of a human screwworm case highlights the potential challenges posed by the spread of this parasite. While the immediate risk to the public is deemed low, the lack of transparency and conflicting information from government and industry sources could erode public trust and create unnecessary anxiety. Clear communication and proactive measures are crucial to mitigate the economic and health impacts of this outbreak.

Keywords: screwworm, human case, CDC, USDA, El Salvador, Maryland, outbreak, cattle, beef, parasite, Central America, Mexico, sterile fly facility, livestock, flesh-eating, travel-related

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