Screwworm Cases Rise in Texas and New Mexico as Livestock Industry Watches Outbreak Closely

U.S. agriculture officials are responding to a growing New World screwworm outbreak after confirmed animal cases increased in Texas and New Mexico, raising concerns among ranchers and livestock experts.

Twelve animal cases have been confirmed so far, according to recent reports citing the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service. The outbreak began with a calf in Zavala County, Texas, on June 3 and has since spread to additional counties in Texas and one county in New Mexico.

The infected animals reportedly include cattle, goats, sheep and one dog. Most of the cases remain active, while one has been listed as inactive. The most recent reported case involved a sheep in Sutton County, Texas.

The New World screwworm is a parasitic fly larva that feeds on living tissue. It can enter open wounds on livestock, pets, wildlife and, in rare cases, people. Once larvae infest a wound, they can cause serious injury and, if not treated quickly, death.

TRENDING TODAY

For decades, the parasite was rarely seen in the United States after a major eradication campaign pushed it out of the country by the 1970s. Its reappearance has alarmed agricultural officials because Texas is the nation’s largest cattle-producing state and the beef industry is already facing high prices and tight supply conditions.

USDA officials are urging ranchers, veterinarians and pet owners to watch for signs of infection. Warning signs may include draining wounds, wounds that grow larger, visible maggots or egg masses, unusual discomfort, and lesions around the ears, nose, genitals or umbilical area. Suspected cases should be reported quickly so animal health officials can investigate and contain the spread.

Officials have stressed that the U.S. food supply remains safe. Screwworm does not infest meat, fruits, vegetables or other food products. The concern is not food contamination, but the risk to animals and the economic damage that could follow if the parasite spreads widely.

Texas Agriculture Commissioner Sid Miller has called for a more aggressive response, warning that every delay gives the pest more time to spread. He has urged deployment of the Screwworm Adult Suppression System, a USDA-developed tool that uses targeted bait to kill fertile adult screwworm flies before they reproduce.

The federal response also includes sterile fly releases, a method used for decades to control screwworm populations. The strategy works by releasing sterile male flies into affected areas, reducing the ability of the pest population to reproduce. Agriculture Secretary Brooke Rollins said the government has already released millions of sterile flies by ground and air as part of the containment effort.

The outbreak has also prompted action beyond the affected states. Pennsylvania’s agriculture department issued a precautionary quarantine order for susceptible livestock coming from affected areas. The order requires veterinary inspections and health documentation in an effort to reduce the risk of the parasite spreading into the state.

The spread into New Mexico has added urgency to the response. In Lea County, officials confirmed a case involving a dog, showing that the parasite is not limited to cattle and other large livestock. That has made awareness important not only for ranchers, but also for pet owners in affected regions.

The outbreak is still limited compared with the much larger screwworm problem seen in parts of Mexico and Central America, but U.S. officials are trying to prevent the parasite from gaining a foothold. Once established, screwworm can be expensive and difficult to control, especially in rural areas with large livestock populations.

For now, containment depends on quick reporting, animal inspections, movement restrictions, sterile fly releases and coordination between state and federal agencies.

Why It Matters

The outbreak matters because screwworm can cause severe harm to livestock and create major economic losses for ranchers. If the parasite spreads further, it could affect cattle operations, animal movement rules and costs across the beef industry.

It also matters because the U.S. spent decades keeping screwworm out of the country. A wider return would test federal and state animal health systems at a time when food and livestock prices are already under pressure.

What Comes Next

USDA and state officials are expected to continue monitoring affected counties, releasing sterile flies and enforcing movement controls where needed. Ranchers and veterinarians will be asked to report suspected cases quickly.

More states may issue precautionary import rules if the outbreak grows or if new cases appear outside Texas and New Mexico.

NewsNation reported that USDA has confirmed 12 New World screwworm cases, including one in New Mexico and others involving livestock in Texas.

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