New World Screwworm
New World Screwworm (NWS) is a parasitic fly that infests or produces maggots in open wounds of animals and people causing serious skin damage and even death if not treated. The NWS fly is currently established in Mexico, Central America, the Caribbean Islands, including Cuba, Haiti and the Dominican Republic and South America.
In June 2026, US Department of Agriculture identified the first recent infestation of NWS in animals in Texas and New Mexico. Confirmed Detections of New World Screwworm | APHIS Currently there are no known cases of NWS infestation in animals or people in Alameda County or California.
If you travel to areas of the world where NWS is present, you can help prevent NWS infestation by keeping open wounds clean and covered with a bandage; sleep indoors in a room with screens on windows and doors; prevent mosquito bites since they can create a wound that the NWS fly can lay eggs in; and check all skin wounds for white fly eggs or maggots.