06/05/2026
USDA Confirms First U.S. Case of New World Screwworm Since 1966 đ¨
The USDA has confirmed the first U.S. case of New World Screwworm (NWS) in nearly 60 years after larvae were discovered in a 3-week-old beef calf in Zavala County, Texas. The infestation was found in the calfâs umbilical area and later confirmed by the USDA National Veterinary Services Laboratories.
The affected ranch is located near the Texas-Mexico border, marking the first confirmed U.S. detection during the current northward spread of New World Screwworm through Mexico and Central America.
In response, USDA and Texas animal health officials have implemented quarantines, increased surveillance, and additional trapping efforts in the area. No additional cases have been reported at this time.
Producers are encouraged to closely monitor newborn calves and animals with wounds and contact their veterinarian if they observe anything suspicious.