Maryland Individual Identified with New World Screwworm Following Trip to El Salvador

A Maryland resident has been diagnosed with New World screwworm after returning from El Salvador, marking the first confirmed U.S. case linked to travel from an outbreak area. The Centers for Disease Control and Prevention (CDC) confirmed the diagnosis on August 4, 2023. Fortunately, the individual has fully recovered, and no further transmission has occurred to other people or animals.

New World screwworm is a parasitic fly whose larvae infest open wounds, consuming living tissue. While it primarily impacts livestock, human cases are rare and can manifest as persistent wounds, visible maggots, and foul odors. Treatment usually involves surgically removing the larvae.

Despite the Maryland case raising alarms, the overall risk to public health in the United States remains low, as the infection does not spread from person to person. However, concerns have intensified among livestock producers due to the recent northward spread of the parasite through Central America and Mexico. In response, the U.S. Department of Agriculture (USDA) has halted imports of cattle from Mexico and is investing in a sterile fly facility in Texas to curb further spread.

Health officials stress the significance of vigilance, particularly for travelers to areas where the parasite is endemic. Recommended preventive measures include keeping open wounds clean and covered, applying insect repellent, and avoiding livestock in affected regions.

The Maryland case highlights the necessity for ongoing monitoring and rapid response strategies to prevent the reintroduction of New World screwworm into the United States, as its establishment could pose severe risks to both human and animal health. Authorities are focused on ensuring the parasite does not gain a foothold in the country.