Click here for the latest information about the New World screwworms

New World screwworms (NWS) are larvae or maggots of the NWS fly (Cochliomyia hominivorax) that cause the painful condition NWS myiasis. This guide is provided to educate and address concerns related to a NWS outbreak in the United States.

About New World Screwworm
NWS was last eradicated from the United States in 1966, through costly efforts by federal and state animal health officials, livestock producers, and veterinary practitioners. Since this time, eradication programs continued to successfully push the pest progressively south through Mexico and Central America. The Darien Gap, known as “the barrier,” helps prevent NWS from reentering Central and North America, but the pest remains endemic in Cuba, Haiti, the Dominican Republic, and South America. Between 2000 and 2023, reintroductions of NWS occurred in free areas of Central and North America and were successfully eradicated. The re-emergence of NWS in Costa Rica, Nicaragua, Honduras, and most recently Guatemala beginning in mid 2023 and early 2024, increases the threat of reintroduction to the United States markedly.

On June 9, the sixth case of NWS was found in a bovine from Edwards County. The infested zone established around the case extends into portions of Sutton and Val Verde Counties. Animal owners can check if they are located in an infested zone and need to follow additional movement requirements by viewing the TAHC interactive case map: https://bit.ly/NWS-ZoneMap

The map will continue to be updated as the situation evolves. See the current movement requirements for all detections here: https://bit.ly/TAHC-NWS