New World screwworm is a parasitic fly whose larvae infest living animals by burrowing into flesh and feeding on living tissue. The pest can affect livestock, pets, wildlife, and, in rare instances, people. If left untreated, infestations can cause severe injury and death.

The United States successfully eradicated NWS in 1966 using sterile insect release programs and later eliminated a localized outbreak in the Florida Keys in 2017. Following the re-emergence of NWS in southern Mexico, USDA suspended imports of live cattle, bison and horses from Mexico and has supported extensive sterile fly releases and eradication efforts. Despite these efforts, approximately 2,000 active cases remain in Mexico.

USDA continues to lead a coordinated “one health” response involving federal, state and international partners. Officials emphasize that New World screwworm is not a food-safety issue, and the current risk to animals and people in the United States remains very low.