On Nov. 26, 2024, the U.S. Department of Agriculture (USDA) announced it had temporarily paused imports of Mexican cattle after a case of New World screwworm (NWS) was identified at the lakeside town of Catazaja in southern Chiapas state.

Mexico’s chief veterinary officer notified the USDA of the detection of NWS in a cow at a checkpoint near the southern border with Guatemala on Nov. 22. The USDA warned that infestations can be difficult to detect at first but can manifest itself through growing wounds, creamy larvae and signs of discomfort.

NWS maggots can enter through an open wound and feed on living flesh of warm-blooded animals, including people. If you see or feel maggots (larvae) in or on a wound or other area of your body, contact your healthcare provider immediately. They will need to remove the larvae, sometimes through surgery. Do not try to remove or dispose of the maggots yourself.