Texas Gov. Greg Abbott (R) has issued a statewide disaster declaration after officials confirmed a second case of the destructive New World screwworm parasite in South Texas, marking the first known U.S. outbreak in decades.
The declaration comes as state and federal authorities scramble to contain the flesh-eating livestock parasite before it can spread further into Texas’ massive cattle industry.
According to state officials, the second confirmed case was identified June 5 in a young calf in Zavala County, just days after the first U.S. case in decades was discovered nearby.
The New World screwworm is considered one of the most damaging livestock parasites in North America. Unlike common flies that feed on dead tissue, screwworm larvae consume living flesh, creating severe wounds that can lead to infection, permanent injury, or death if left untreated.
Officials said the first case was detected June 3 in a three-week-old calf near La Pryor, Texas, roughly 30 miles from the Mexican border. The second infected calf, approximately one month old, was found about 5.6 miles away.
The discoveries prompted immediate action from state and federal agencies.
Abbott’s disaster declaration authorizes state resources to be deployed, prioritizes emergency response efforts, and strengthens coordination among agencies working to contain the parasite.
“This pest poses a significant threat to Texas livestock, wildlife, and the broader agricultural economy,” state officials said as response operations expanded.
Authorities have established a 20-kilometer quarantine zone covering portions of Zavala and Uvalde counties. Movement restrictions have been imposed on livestock, wildlife carcasses, and other warm-blooded animals that could potentially spread the infestation.
The New World screwworm was eradicated from the United States in 1966 after a massive federal campaign that relied heavily on the Sterile Insect Technique, commonly known as SIT.
Under that program, millions of male flies are bred in specialized facilities, sterilized through radiation, and released into the wild. Because female screwworm flies mate only once, breeding with sterile males prevents viable offspring and gradually collapses the population.
State and federal officials are once again relying on that strategy.
Texas facilities are already producing and releasing millions of sterile flies weekly in an effort to halt the parasite’s advance. More than 8,000 monitoring traps have also been deployed along the southern border to detect additional infestations, Trending Politics reported.
The current outbreak follows a steady northward migration of the parasite through South America, Central America, and Mexico beginning around 2023.
Agricultural experts warn that an uncontrolled outbreak could have devastating consequences for the cattle industry.
Before eradication efforts succeeded in the 1960s, screwworm infestations caused significant livestock losses across the southern United States. Animals frequently suffered severe tissue damage, weight loss, secondary infections, and death.
Wildlife populations were also heavily impacted. Historical outbreaks in Texas resulted in substantial losses among white-tailed deer and other game species, with some regions reporting mortality rates exceeding 50 percent.
Texas currently leads the nation in cattle production, making the state particularly vulnerable to economic disruption from any widespread infestation.
The Texas Animal Health Commission and Texas Parks and Wildlife Department are leading response efforts through a specialized New World Screwworm Response Team.
Officials are urging ranchers, veterinarians, hunters, and animal owners to closely inspect animals for unusual wounds, larvae, or signs of infection and immediately report suspected cases.
The outbreak remains limited to two confirmed cases, but authorities say aggressive containment measures will be critical to preventing a larger crisis for Texas agriculture and livestock producers nationwide.
