U.S. regulators have authorized the emergency use of ivermectin injections to help prevent New World screwworm infestations in certain cattle classes. The move comes as animal health officials step up preparedness efforts amid renewed concern along the southern U.S. border.
The U.S. Food and Drug Administration issued an Emergency Use Authorization (EUA) allowing IVOMEC (ivermectin) 1% Injection to be used at specific, high-risk points in cattle management. Producers may administer the product within 24 hours of birth, at castration, or when cattle develop open wounds.
The authorization excludes female dairy cattle producing milk for human consumption and calves intended for veal production.
Preparing for a High-Risk Pest
New World screwworm (Cochliomyia hominivorax) poses a serious threat to livestock. Its larvae feed on the living tissue of warm-blooded animals and can cause severe injury or death if left untreated.
The United States eradicated the pest decades ago. However, it remains endemic in parts of Central and South America. Recent detections in northern Mexico, including the border state of Tamaulipas, have raised concerns among U.S. animal health officials.
Although the pest has not been found in the United States, regulators continue to emphasize early prevention and rapid response planning.
Why the FDA Issued an EUA
According to the FDA, no approved and readily available alternatives exist to prevent screwworm infestations at key intervention points in cattle. Based on that determination, the agency authorized emergency use of the product to ensure access if an incursion occurs.
This decision marks the first time an over-the-counter animal drug has received an EUA for preventing New World screwworm infestations in cattle. The authorization reflects both the severity of the threat and the limited prevention tools currently available.
Scope and Duration of the Authorization
The EUA remains in effect only while federal authorities determine that emergency conditions exist under the Federal Food, Drug, and Cosmetic Act. The agency may revoke the authorization if conditions change or if the declaration ends.
The product manufacturer, Boehringer Ingelheim, supplies IVOMEC for livestock use. Under the EUA, producers may use the product only for prevention, not for treating established infestations.
Ongoing Preparedness Efforts
Animal health experts stress that screwworm control depends on early detection, strong biosecurity, and coordinated action. Infestations often begin at navels, castration sites, or untreated wounds.
Federal agencies, including the U.S. Department of Agriculture, continue outreach efforts to educate producers on identifying symptoms and reporting suspected cases. Government resources also outline response protocols should the pest reappear.
While the EUA does not indicate that screwworm is present in the United States, it highlights increased vigilance among regulators. Officials aim to protect livestock health, producer livelihoods, and the stability of the food supply.
