FDA grants first conditional approval for drug to combat New World Screwworm in cattle

USA – The U.S. Food and Drug Administration (FDA) has granted its first-ever conditional approval for a drug targeting New World screwworm (NWS) infestations in cattle, a move aimed at protecting U.S. livestock against one of the most destructive parasites.

The injectable solution, marketed as Dectomax-CA1 by Zoetis, will provide prevention and treatment of NWS larval infestations and reinfestation for up to 21 days.

The conditional approval, announced this week, applies exclusively to cattle and underscores the agency’s recognition of the urgency surrounding the parasite threat.

New World screwworms, the larvae of a parasitic fly, are considered life-threatening to livestock, causing severe tissue damage and, if untreated, death. 

The parasite has been eradicated from the U.S. since the 1980s but remains a looming threat due to the risk of reintroduction.

“We understand the urgency with which America’s farmers and ranchers are asking for tools to fight New World screwworm,” said FDA Commissioner Marty Makary, M.D., M.P.H. 

“Today’s conditional approval – the first in the U.S. for NWS – shows our dedication to rapidly advancing important animal medicines when they are needed most. We continue to work tirelessly to complete review of other NWS products to protect multiple animal species in the U.S.”

The FDA noted that Dectomax-CA1 qualified for conditional approval because it addresses an unmet need in animal health and because proving its effectiveness requires complex studies.

Balancing speed and safety

Under the conditional approval, the FDA confirmed that the drug has a “reasonable expectation of effectiveness” and meets safety standards for both animals and humans. 

“We are making this treatment available to cattle producers immediately while the sponsor collects the data needed for a full approval,” said Timothy Schell, Ph.D., acting director of the FDA’s Center for Veterinary Medicine. 

He added that the FDA will continue to expedite review of animal drugs to help the U.S. fight this devastating threat to the nation’s livestock and the livelihoods of the farmers and ranchers who care for them.

Dectomax-CA1 builds on Zoetis’ existing product, Dectomax, which is already fully approved for controlling nematode and arthropod parasites in cattle and swine. 

Both formulations share the same active ingredient, doramectin injection, at the same dose. Because prior approvals established safety, manufacturing, and food safety standards, new data for these areas were not required for the conditional approval.

Usage guidelines and precautions

The withdrawal period for cattle treated with Dectomax-CA1 is 35 days, identical to that of Dectomax.

However, the drug is not approved for use in female dairy cattle 20 months of age or older, and its safety in pre-ruminating calves has not been established. 

The FDA has stressed that producers should use Dectomax-CA1 responsibly and only when medically necessary, to reduce the risk of antiparasitic resistance.

The product, manufactured by Zoetis in Kalamazoo, Michigan, will be available in 250 mL and 500 mL bottles. The labelling will include indications for both Dectomax and Dectomax-CA1, with each carrying a unique application number.

Subscribe to receive our email newsletters with the latest news and insights from Africa, Middle East and around the world. SUBSCRIBE HERE