New World Screwworm Outbreak: How to Protect Your Pets in Texas and New Mexico
Veterinarians and humane societies issued warnings Wednesday, after more than 30 confirmed cases of New World screwworm were detected in Texas and New Mexico. The flesh-eating parasite, which targets live tissue in any mammal, poses a threat to the $113 billion U.S. cattle industry and domestic pets.
The $113 Billion Exposure: Why Screwworm Threatens U.S. Livestock
The New World screwworm is not a typical scavenger. Unlike most fly larvae that consume dead material, these parasites feed on live flesh and fluids. The migration pattern is aggressive; the fly moved north from Panama in 2024 and through Mexico in 2025 before crossing into the U.S. in June.
For the cattle industry, the financial stakes are immense. A single infestation can lead to rapid tissue degradation, shock, and death if left untreated.
The vulnerability is not limited to cattle. According to the American Veterinary Medical Association, newborn animals and those with open wounds—including surgical sites or simple tick bites—are at the highest risk. Aaron Grady, executive director of the Houston Humane Society, confirmed during a webinar that even a minor tick bite can serve as the entry point for an infestation.
Clinical Indicators and Immediate Veterinary Intervention
Early detection is the way to prevent fatality. Melissa Stansell, a veterinarian at Austin Pets Alive!, identifies specific behavioral and physical red flags that pet owners must monitor in southern and southwestern Texas and southeastern New Mexico.
- Physical Signs: Visible maggots or movement within a wound and a distinct foul smell.
- Behavioral Shifts: Restlessness, anxiety, or “hyper-fixating” on chewing a specific area of the body.
- Systemic Risk: Death can occur from shock due to extreme pain or if larvae migrate into vital organs.
The solution is pharmacological. Stansell notes that prescription flea and tick medications are effective because their chemical compositions kill the larvae as they ingest blood and tissue. When combined with antibiotics, the condition is treatable. “It is only fatal if left untreated,” Stansell stated.
The USDA’s $771 Million Eradication Strategy
The U.S. government is not relying on the winter freeze to kill off this tropical species. Instead, the USDA is reviving an eradication method that worked decades ago: the Sterile Insect Technique.
The process involves breeding sterile male flies and releasing them into the wild. Because the female New World screwworm mates once in her monthslong life, a pairing with a sterile male ensures the eggs never hatch, effectively crashing the local population.
The USDA recently invested $21 million to convert a facility in southern Mexico from fruit fly production to screwworm breeding. The agency also plans to spend $750 million on a new fly factory in Texas, set to open next year.