New World Screwworm Threat Sparks Concern Across Texas. The Texas Parks and Wildlife Department (TPWD) is calling on Texans to stay vigilant as the New World Screwworm (NWS) makes its way closer to the Lone Star State. While it hasn’t been detected “in Texas yet,” the parasite was recently found in Chiapas, Mexico, near the Guatemala border, sparking increased import restrictions and heightened surveillance. This dangerous little pest threatens our livestock, wildlife, pets, and even humans.