WASHINGTON, D.C. – Federal health officials have confirmed a single case of New World screwworm (NWS) in the United States tied to international travel, prompting precautionary monitoring across parts of the Mid-Atlantic.

The U.S. Department of Health and Human Services (HHS) and the Centers for Disease Control and Prevention (CDC) identified the case earlier this month in a patient who returned from El Salvador. The Maryland Department of Health assisted in the investigation. Officials emphasized that the risk to public health remains very low.

To support CDC’s response, the U.S. Department of Agriculture (USDA) launched targeted surveillance within a 20-mile radius covering areas of the District of Columbia, Maryland, and Virginia. To date, no screwworm detections have been found in humans, livestock, or wildlife. USDA confirmed the last known U.S. outbreak was in the Florida Keys in 2017.

New World screwworm is a parasitic fly that can cause severe infestations in both animals and humans. Although rare in the United States, isolated travel-related cases have been documented in past years. Federal officials noted that all previous incidents were contained and did not result in transmission to livestock.

Agriculture Secretary Brooke Rollins has already unveiled a five-part strategy to protect the nation from potential outbreaks, including ongoing trapping along the U.S.–Mexico border and construction of a sterile fly production facility to support rapid response efforts. “Public health and safety and our joint effort to combat the northward spread of NWS from Mexico into the United States is the top priority,” USDA stated in its release.

Officials reiterated that while additional traveler-associated cases may appear, precautionary surveillance ensures quick detection and prevention of further spread.