Texas Gov. Greg Abbott (R-TX) confirmed Friday that a calf in Zavala County tested positive for the New World screwworm parasite.

The discovery marks a significant biological threat to the state's livestock industry and represents the first confirmed case of the parasite in the U.S. since the 1960s [1]. Because the parasite can cause severe tissue damage to livestock, the state is mobilizing emergency containment measures to prevent a wider outbreak.

Abbott addressed the situation on June 5, 2026, and said that the parasite does not pose a risk to the consumer food supply. "There is no food safety issue," Abbott said [4].

Other state officials echoed this sentiment during the announcement. They said the situation is not a food safety or virus issue [5]. The focus remains on the health of the animals, and the protection of the cattle industry in South Texas.

To combat the spread, state leadership is looking to accelerate the development of a fly breeding factory. This facility would be used to produce sterile insects to disrupt the parasite's life cycle and eliminate the population without widespread chemical use [6].

Zavala County officials and state veterinarians are currently working to isolate the affected area. The state's response aims to prevent the parasite from migrating to other regions of the U.S., or impacting other livestock populations across the border.

“"There is no food safety issue."”

The re-emergence of the New World screwworm in Texas threatens a decades-long period of eradication in the U.S. If not contained quickly, the parasite could cause significant economic losses for the cattle industry through livestock mortality and increased veterinary costs. The state's push for a sterile insect breeding facility indicates a shift toward biological control methods to maintain the U.S. status as screwworm-free.