New World Screwworm Cases Reported in Texas and New Mexico

The U.S. Food and Drug Administration has issued an emergency use authorization for nitenpyram, a medication designed to combat the New World screwworm parasite in pets. This action comes amid growing concern following the identification of screwworm cases in Texas and New Mexico, marking the first instances in Texas since 1966.

The flesh-eating New World screwworm lays eggs in open wounds, noses, ears, eyes, or mouths of warm-blooded animals. These eggs develop into larvae that feed on flesh, and if left untreated, the infestation can be fatal. While primarily affecting livestock, the flies can target any warm-blooded animal, including pets and humans.

The authorized medication, nitenpyram, is effective in killing most screwworm larvae within hours of the first dose, with a second dose administered six hours later. Veterinarians may also need to manually remove larvae. Signs of infection include visible maggots, worsening skin wounds, foul odors, and bleeding sores. Nitenpyram treats existing infestations but does not prevent them. The FDA notes that dosage is based on the pet's weight and is available over the counter, though consulting a veterinarian is advised to prevent repeat infestations.