The U.S. Food and Drug Administration issued an Emergency Use Authorization on September 3, 2026, for nitenpyram tablets, the active ingredient in the flea treatment Capstar. The authorization allows the tablet to be used off-label to prevent and treat New World screwworm infestations in cats, kittens, dogs, and puppies, according to Catster.
The article says the authorization fills a gap because prevention had been missing from the drug options for dogs and cats.
New World screwworm is a fly, Cochliomyia hominivorax. Its larvae feed on living tissue, often starting in or around a wound. The article says the infestation can cause extensive tissue damage and, without prompt treatment, can be life-threatening.
The article reports that the screwworm has been detected in the United States. It says the USDA is maintaining surveillance and response efforts, including in Texas, where "zones of infestation" have been established.
The article cites an estimated $132.1 million in costs to producers during a 1976 Texas outbreak, equal to about $740 million in 2024 dollars. It also says disruption to live cattle exports from Mexico has been estimated to have cost that country's livestock sector around $1.8 billion.
According to the article,