The Brief Second case of New World screwworm detected in Texas New case is in a one-month-old calf in Zavala County This case was found 5.6 miles from the first case ZAVALA COUNTY, Texas - A second case of New World screwworm has been detected in Texas. RELATED COVERAGE: Flesh-eating screwworm in Texas: Gov. Abbott signs statewide disaster declaration What they're saying The US Department of Agriculture has confirmed the second case in a one-month-old calf in Zavala County.