Screwworm reaches Texas, but no cases reported in the Rio Grande Valley

Rio Grande Valley county leaders are monitoring the New World screwworm threat after federal officials confirmed the first U.S. case in a South Texas calf this week.

Hidalgo and Cameron county officials said Thursday that no local cases have been reported. But both counties said they are coordinating with state and federal agencies as response efforts continue following the detection in Zavala County.

The U.S. Department of Agriculture confirmed the case Thursday after a New World screwworm was found in a three-week-old calf. Zavala County is about 280 miles from McAllen and roughly 300 miles from Cameron County.

Federal and state officials have responded by establishing an infested zone, increasing animal and fly surveillance, conducting epidemiological investigations, implementing quarantines and movement controls, and releasing sterile flies to help prevent the pest from spreading.

Hidalgo County Judge Richard F. Cortez said the county is working with the Texas Animal Health Commission and the Texas Department of State Health Services to prepare in case a local case is detected.

“We are closely monitoring the situation involving the New World screwworm recently reported in Zavala County,” Cortez said. “While there have been no reported cases in Hidalgo County, we are taking this matter seriously.”

Cortez said Hidalgo County also is communicating with county judges in Cameron, Starr and Willacy counties to coordinate information and response efforts.

“Protecting the health of our communities, livestock, and agricultural industry remains a top priority,” Cortez said.

Cameron County officials also said they are in communication with state and federal agencies to ensure local departments remain informed and prepared. The county said it is working to increase public awareness among livestock owners, pet owners, veterinarians and animal caretakers.

New World screwworms can infect livestock, wildlife, pets and other warm-blooded animals, especially those with open wounds or sores. Infestations in humans are rare, but officials are urging residents to remain vigilant.

Livestock owners and residents are encouraged to watch for unusual or worsening wounds, larvae, or abnormalities around body openings or the navels of newborn animals.

Suspected cases should be reported to a private veterinarian and the Texas Animal Health Commission at 1-800-550-8242.

“At this time, there is no threat to the food supply,” Hidalgo County said in its release, citing USDA confirmation that New World screwworms do not infest meat, fruits, vegetables or other food products.

The pest was eradicated from the United States decades ago but has persisted in parts of South and Central America. Its northward movement has renewed concern among livestock producers and public officials in Texas.

Current eradication efforts rely on the release of sterile male flies, a method designed to interrupt reproduction and eliminate screwworm populations. Cameron County officials said sterile flies from a reproduction facility in Panama are currently being released in South Texas.

The USDA is also building a large-scale sterile fly production facility in Edinburg. The facility is expected to be completed in November 2027.

Regional leaders previously discussed the threat during a May 18 press conference involving Rio Grande Valley county judges, state agencies and animal industry partners.

County officials said they will continue monitoring the situation and provide public updates as new information becomes available.