What Virginia Livestock Owners Should Know About New World Screwworm

New World Screwworm (NWS) has been confirmed in several animals in south Texas and New Mexico — the first U.S. detections since the pest was eradicated here in the 1960s. Current cases are more than a thousand miles from Virginia, and federal and state agencies are responding aggressively. Still, awareness is important for producers and pet owners everywhere.

What Makes NWS Different

Unlike common maggots, NWS larvae burrow into living, healthy tissue, causing severe wounds and — if untreated — potentially death. The fly spreads through animal movement: livestock, wildlife, pets and, rarely, people. One important note: screwworms do not infest meat, dairy or produce. The U.S. food supply is safe.

Know the Signs

The fly: Metallic blue-green body, three dark stripes on the back, orange eyes.

The larvae: Creamy white, tapered, spine-covered (resembling a screw). Hundreds to thousands can appear within days, turning pinkish-red after about a week.

Watch your animals for:

• Larvae or eggs near wounds or body openings (navel, nose, ears, genitals)

• Wounds that enlarge or deepen; odor of decay

• Head shaking, rubbing, irritation

• Lethargy, isolation or poor appetite

  
  

What to Do

Treatments have been approved through FDA emergency use authorization for both livestock and companion animals. If you suspect NWS:

1. Contact your veterinarian immediately.

2. Call VDACS Office of Veterinary Services at 804-786-2483. Rapid reporting is critical to limiting spread.

For the latest case updates, visit screwworm.gov.