FDA authorizes emergency use of nitenpyram for screwworm

The U.S. Food and Drug Administration has granted emergency use authorization for an over-the-counter drug to treat New World screwworm infestations in cats and dogs, a response to the first confirmed domestic cases of the parasite in decades. The authorization, announced on June 11, allows for the use of generic nitenpyram tablets for pets weighing at least two pounds and at least four weeks old.

This action follows the detection of New World screwworm in multiple animals in Texas and New Mexico earlier this month. Cases have been confirmed in cattle, a goat, and a dog, with officials announcing a total of five confirmed U.S. cases as of this week. These are the first known domestic animal infections since at least 2017, when a small outbreak was eradicated in Florida. The parasite, officially eradicated from the United States in 1966, had been moving northward after reappearing in southern Mexico in 2024.

The New World screwworm is a parasitic fly whose larvae consume the living flesh of warm-blooded animals, including livestock, pets, wildlife, and, rarely, humans. Female flies lay eggs in open wounds or mucous membranes, and the hatching maggots burrow into tissue, causing a...