Key facts
- The New World screwworm has reappeared in the United States, with cases confirmed in Texas and New Mexico.
- The parasite primarily affects livestock but can infect humans and pets by laying eggs in open wounds.
- Symptoms of screwworm infestation include visible larvae, destruction of healthy tissue, and foul odor from wounds.
- If left untreated, screwworm infections can be deadly to humans.
- Treatment involves the surgical removal of all eggs and larvae from the affected area.
After decades of successful eradication efforts, the New World screwworm, a parasitic fly capable of infecting humans and animals, has returned to the United States. Confirmed cases have been reported in Texas and New Mexico, raising concerns about potential widespread damage to American livestock and cattle.
The screwworm fly deposits its eggs in open wounds, noses, ears, eyes, or mouths of warm-blooded animals. These eggs hatch into larvae, commonly known as maggots, which then feed on the host's living flesh, burrowing deeper into the tissue. While primarily a threat to livestock such as cows and goats, the flies can lay eggs on any warm-blooded animal, including humans and pets. One confirmed case in Lea County, New Mexico, involved a small pet dog.