Texas authorities have confirmed a second case of New World screwworm infection, prompting Governor Greg Abbott to declare a statewide disaster and escalate the emergency response. The two confirmed infections were detected about five miles apart in Zavala County, southwest of San Antonio.
The New World screwworm is a parasitic fly whose larvae feed on living flesh in warm-blooded animals. When eggs hatch, the maggots burrow through living tissue, causing a painful condition called screwworm myiasis that can be fatal if untreated. The first case was identified in a three-week-old calf with an umbilical lesion, while the second was confirmed after the USDA tested additional suspect cases.
These are the first screwworm detections in the United States since the 1960s. The parasite's appearance marks the northward progression of a disease threat that has been moving from Central America since 2023. Texas animal health officials said they have been preparing for a potential resurgence for over two years and are now implementing those plans.
State and federal authorities have established an infested zone and imposed animal movement restrictions to prevent further spread. Officials are dispersing millions of sterile male screwworm flies in the affected area. These sterile insects cannot reproduce with wild females, making this a proven and effective control method when combined with enhanced surveillance, prompt wound treatment, and public education.
Governor Abbott warned that it will likely be "an extraordinarily challenging summer" for infected areas, as warm weather typically accelerates parasite spread. The Texas Animal Health Commission director, Dr Bud Dinges, urged all animal owners and caretakers to remain vigilant for larvae in animal wounds and report any suspected cases immediately.
The USDA confirmed the food supply remains safe, noting that screwworms do not infect meat, fruits, vegetables, or other food products. However, the outbreak poses significant economic risks to Texas ranchers through potential animal deaths and increased labor and treatment costs.
The detection also has broader trade implications. For over a year, the U.S.-Mexico border has been closed to live cattle imports as the disease moved northward, contracting the beef industry to a 75-year low. The U.S. previously imported more than 1 million cattle annually from Mexico, representing 4 to 5 percent of all cattle sold for beef production.
Following the Texas infections, Canada's food inspection agency announced a temporary ban on livestock from Texas. Animals that were in Texas within 21 days before crossing into Canada will not be accepted. Canadian officials noted the parasite is unlikely to establish in their colder climate but warned farmers to monitor livestock for wounds accompanied by discharge or foul odor.