The U.S. Food and Drug Administration has greenlit the emergency use of an over-the-counter animal medication to combat infections caused by the New World screwworm, a parasite that can be fatal for cats and dogs.
This decision follows reports of New World screwworm infections surfacing in two states. In Texas, the parasite has been identified in cows and goats, while in New Mexico, a dog has been affected.
These incidents mark the first recorded cases of such infections in animals since at least 2017, when a minor outbreak was detected and subsequently eliminated in Florida, according to the U.S. Department of Agriculture (USDA).
The initial case this month was identified in a three-week-old calf in Texas, found in the animal’s umbilical area.
The FDA has approved the use of generic Nitenpyram Tablets (nitenpyram) for addressing New World screwworm infestations in dogs, puppies, cats, and kittens that weigh a minimum of two pounds and are at least four weeks old.
The New World screwworm is a parasitic fly species that feeds on the tissue or flesh of warm-blooded animals and people to complete parts of its life cycle, the Centers for Disease Control and Prevention (CDC) said.
The infestation begins when adult females are attracted to open wounds and body openings, such as the eyes, nose, mouth or genitals.
They lay their eggs — usually 200 to 300 at a time — in these vulnerable areas, which quickly hatch into maggots that burrow into the wound or opening to feed on the flesh, a painful condition known as myiasis.
Nitenpyram is the first animal drug available to treat New World screwworm, the FDA said.
“The FDA has spent nearly a year fast-tracking reviews and readying for the arrival of New World screwworm in the US,” said Acting FDA Commissioner Kyle Diamantas.
The FDA said nitenpyram works quickly, killing most larvae within hours of the first dose.
A second dose should be administered six hours after the first.
Dosage amounts are based on the pet’s weight.
Because the effects are short-acting, Nitenpyram Tablets do not prevent NWS myiasis or protect against reinfestation, the FDA said.
“Following treatment with Nitenpyram Tablets, a veterinary professional may need to physically remove any remaining live or dead larvae,” the FDA said.
“This task is best performed by someone with training in veterinary medicine to minimize the risk of infection or further tissue damage.”