FDA approves ivermectin for cattle screwworm, 14th emergency authorization

USDA confirms 47 cases as Texas seeks ivermectin in feed for screwworm

The Food and Drug Administration on Thursday issued an Emergency Use Authorization for the generic ivermectin product Bimectin to treat New World screwworm infestations in cattle, the 14th such authorization the agency has issued against the flesh-eating parasite as it spreads through Texas.

The approval permits Bimectin injections in cattle when administered within 24 hours of birth, at the time of castration, or at the appearance of wounds, the FDA announced. Bimectin remains unauthorized for use in lactating dairy cows or in calves that will be processed for veal.

The Department of Agriculture has confirmed 47 domestic cases of New World screwworm, or NWS, in animals as of Thursday. NWS is widely feared as a serious health and economic threat that could cost billions of dollars in losses to cattle, bison and horses.

The pest was eradicated from the United States in 1966 and eliminated as far south as Panama by 2000, but reemerged in 2022 and has continued moving north through Central America and Mexico. The U.S.-Mexico border was closed last year to protect U.S. animals from the threat. The ban was subsequently lifted on July 26.

Texas Agriculture Commissioner Sid Miller last month urged the FDA to authorize ivermectin in feed as an additional tool to combat the growing NWS threat. Injectable ivermectin is not enough to keep pace with the outbreak and protect livestock from further infestations, he asserted.

“Texas ranchers are fighting for their livelihoods and the security of the American food supply. They don’t have time to wait,” Miller said. “We’ve already seen this parasite spread across multiple Texas counties in just a few weeks. Every day we delay is another day the New World screwworm gains ground. We need every effective weapon available, and we need it now.”

The Texas Grain and Feed Association “has committed to rapidly manufacture and distribute medicated feed upon approval, ensuring producers can begin using it without delay,” Miller noted.