The New World Screwworm (NWS), a parasite that consumes living flesh, has been detected in New Mexico, marking its spread to a second U.S. state. The U.S. Department of Agriculture confirmed the first case in the state, involving a dog in Lea County, which borders Texas.
This discovery brings the total number of confirmed NWS cases in the U.S. to five. Four cases had previously been reported in Texas. The parasite lays hundreds of larvae in the wounds of animals and people, which hatch within hours and begin feeding on tissue. Left untreated, these infestations can lead to severe wounds, infections, and potentially death.
While the recent U.S. cases have involved animals, including three calves, thousands of human infections have been reported worldwide. As of June 8, the Centers for Disease Control and Prevention (CDC) has identified over 2,100 human cases of NWS infestations, primarily in Mexico and Central America.
Local and Regional Response
In response to the threat, three counties in Texas—Kinney, Jim Hogg, and Uvalde—have declared local states of disaster. Similar declarations are pending in Webb, La Salle, and Val Verde counties. Some local officials have urged President Donald Trump to issue a national emergency declaration, seeking additional personnel, funding, and resources to combat the pest's potential spread.
Texas Governor Greg Abbott stated that protecting ranchers, livestock producers, deer breeders, and the state's economy from this pest is a top priority. He noted that the pest had been eradicated from the U.S. previously and expressed confidence in doing so again in cooperation with federal partners. Texans are advised to remain alert, inspect animals daily for wounds, and report any suspected cases immediately.
Historical Context and Future Concerns
The New World Screwworm was last detected in Texas 60 years ago. It was eradicated in the U.S. by 1982 through a method involving the sterilization of male flies with radioactive gamma rays to prevent reproduction. The economic impact of screwworms in the U.S. historically cost approximately $200 million in livestock losses, equivalent to about $1.8 billion today.
Officials noted that cases were discovered in southern Mexican states along migrant caravan routes a year ago. Researchers have expressed concern that the flies may be difficult to contain at the U.S.-Mexico border and could begin infesting the southern U.S. within two decades due to rising temperatures. Research suggests that Gulf states, including Texas, Florida, and Louisiana, could face potential risks to cattle and human populations by 2055.
Prevention and Symptoms
The CDC recommends preventative measures in areas where New World screwworm flies are present. These include keeping all open wounds clean and covered, even minor cuts. Individuals are advised to wear loose-fitting long-sleeved shirts, pants, hats, and socks to minimize exposed skin. The use of EPA-registered insect repellent and sleeping indoors or in screened rooms are also recommended.
Early symptoms of a screwworm infection can include unexplained painful wounds or sores that do not heal, a foul odor or bleeding from the affected site, or the sensation of maggots or movement within a wound or near the nose, mouth, eyes, or ears.