FDA Issues EUA for Topical Drug to Prevent New World Screwworm in Multiple Species

The US Food and Drug Administration (FDA) has issued an emergency use authorization for a topical drug to prevent New World screwworm (NWS) in multiple species.

This wound spray is authorized for use in sheep, cattle, goats, swine, camelids, and select wildlife species as the New World screwworm continues to spread in the US.

The FDA has issued an emergency use authorization for dicyclanil topical suspension (CLiK Extra; Elanco) wound spray, expanding the list of products available to prevent New World screwworm (NWS) myiasis. The authorization covers sheep, cattle, goats, swine, and camelids (eg, camels, llamas, alpacas), as well as several captive and captured wildlife species, including cervids (eg, deer and elk), American bison, bighorn sheep, and Sonoran pronghorn.

The agency concluded that, based on the totality of available scientific evidence, the wound spray may be effective for preventing NWS myiasis when used as authorized, and that its known and potential benefits outweigh its known and potential risks.

The wound spray works by acting as an insect growth regulator, disrupting larval development and halting the parasite's life cycle before it can cause tissue damage in the host animal. It is authorized for application on or around wounds at the time they appear or are created, including birth wounds and those resulting from surgical or husbandry procedures such as dehorning, ear tagging, castration, tail docking, and shearing.

The FDA recognizes that the impact of NWS extends beyond the farm gate. "The FDA recognizes that the impact of [NWS] extends beyond the farm gate," said Timothy Schell, PhD, director of the FDA's Center for Veterinary Medicine. "Authorizing this product for captive and captured wildlife species, including bighorn sheep, Sonoran pronghorn, American bison, and cervids like deer and elk, is about protecting these animals and helping ensure they do not contribute to the spread of NWS in the United States."

The EUA does not cover treatment of existing infestations. If a wound is already infested, or if an infestation develops after the product is applied, the FDA advises contacting a veterinarian to discuss treatment options.

Dicyclanil topical suspension is available over the counter for topical use and is not approved or conditionally approved by the FDA for any indication. Detailed product information, including food safety data, is available in the agency's fact sheet.

The authorization will remain in effect until it is revoked or until the US Department of Health and Human Services terminates the declaration supporting the use of emergency-authorized animal drugs against NWS.

**Species Covered by EUA**

| Species | Type | | --- | --- | | Sheep | Livestock | | Cattle | Livestock | | Goats | Livestock | | Swine | Livestock | | Camelids | Livestock | | Cervids (eg, deer and elk) | Wildlife | | American bison | Wildlife | | Bighorn sheep | Wildlife | | Sonoran pronghorn | Wildlife |