New World Screwworm Confirmed in Texas: What Animal Owners Need to Know
The recent confirmation of New World screwworm (NWS) in Texas has brought renewed attention to a pest that many producers hoped would remain a problem of the past. While the detection is concerning, animal health officials emphasize that awareness, early detection, and prompt reporting are the most important tools available to help prevent further spread.
Whether you own livestock, horses, exotic animals, wildlife, or pets, now is the time to become familiar with New World screwworm and the signs animal owners should watch for.
What Is New World Screwworm?
New World screwworm is the larval stage of a fly known as Cochliomyia hominivorax. Unlike many fly larvae that feed on dead tissue, New World screwworm larvae feed on the living tissue of warm-blooded animals.
Adult female flies are attracted to wounds and natural openings where they lay eggs. Once the eggs hatch, the larvae begin feeding on living tissue, creating painful wounds that can rapidly worsen if left untreated.
What Animals Can Be Affected?
According to the Texas Animal Health Commission, New World screwworm can affect any warm-blooded animal, including:
- Cattle
- Horses
- Sheep
- Goats
- Swine
- Deer and other wildlife
- Exotic animals
- Pets
- Humans in rare cases
Because the pest targets living tissue, any animal with an open wound may be at risk.
Why This Matters to Ranch Owners, Horse Owners, and Hunting Properties
For Texas landowners, New World screwworm is more than just a livestock issue. The potential impact reaches across many types of rural properties and animal operations.
Cattle producers may need to increase monitoring of herds, especially around branding, castration, dehorning, calving, and other situations where wounds may occur. Horse owners should closely inspect cuts, insect bites, surgical sites, and other injuries that could attract flies.
Wildlife ranches, hunting properties, and exotic game operations should also remain vigilant. Deer, exotic species, and other wildlife can be susceptible to infestation, particularly if injuries or wounds are present. Because many Texas ranches manage a combination of livestock, horses, wildlife, and pets, awareness across the entire property is important.
Landowners should also recognize that routine animal management practices may require additional attention during periods of increased screwworm risk. Early detection and rapid response can help reduce complications and support broader containment efforts.
Where Should Owners Be Looking?
Animal owners should routinely inspect animals and pay close attention to:
- Open wounds
- Surgical sites
- Castration sites
- Dehorning sites
- Branding sites
- Shearing wounds
- Tick and insect bite locations
- Ear injuries
- Predator wounds
- Newborn navels
- Any area that appears irritated, swollen, or slow to heal
Regular inspections are especially important during fly season and after any procedure or injury that creates an open wound.
Signs of a Possible Infestation
New World screwworm infestations often begin in a wound and may become progressively worse over time.
Signs that may indicate an infestation include:
- Wounds that continue to enlarge instead of healing
- Bloody or foul-smelling discharge
- Visible larvae within a wound
- Irritation around the affected area
- Animals repeatedly licking, biting, or rubbing a wound
- Signs of discomfort or distress
Because infestations can progress quickly, early detection is critical.
What Should You Do If You Suspect Screwworm?
If you observe a suspicious wound or suspect New World screwworm:
- Contact your veterinarian immediately.
- Report suspected cases to the Texas Animal Health Commission.
- Avoid moving affected animals until guidance is received.
- Continue monitoring other animals on the property for signs of infestation.
Prompt reporting helps animal health officials respond quickly and reduce the risk of spread.
What Is Being Done?
The Texas Animal Health Commission and USDA Animal and Plant Health Inspection Service (APHIS) are actively working together to monitor, contain, and eradicate New World screwworm.
Response efforts include:
- Increased surveillance and monitoring
- Enhanced trapping programs
- Animal movement controls when necessary
- Producer and veterinary outreach
- Coordination with state, federal, and international animal health partners
The United States successfully eradicated New World screwworm in the past through coordinated efforts, and officials are utilizing many of those same proven strategies today.
Stay Vigilant
The recent detection of New World screwworm in Texas is a reminder that animal health requires constant vigilance. Livestock producers, horse owners, wildlife managers, pet owners, veterinarians, and rural landowners all play an important role in protecting animal health.
Routine inspections, proper wound management, and immediate reporting of suspicious cases remain the best defenses against this pest.
Learn More
For the most current information and updates, visit:
• USDA APHIS New World Screwworm Current Status Page
https://www.aphis.usda.gov/animals/animal-health/livestock-and-poultry-disease/current-status
• Texas Animal Health Commission New World Screwworm Resource Center
https://www.tahc.texas.gov/emergency/nws.html
