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Texas ranchers and wildlife managers now have a new tool to help protect animals from New World screwworm, as the parasitic fly continues to spread in the state.
The U.S. Food and Drug Administration has issued an Emergency Use Authorization for CLiK Extra, a wound spray that can help prevent New World screwworm infestations in livestock and several species of wildlife.
The authorization comes as the U.S. responds to an outbreak that has resulted in 45 confirmed New World screwworm infestations, according to the latest federal data.
New World screwworm is a parasitic fly whose larvae feed on the living tissue of animals. Female flies lay their eggs in wounds or other vulnerable areas. Once the larvae hatch, they can cause severe tissue damage and, in some cases, death.
The FDA said CLiK Extra may be effective in preventing New World screwworm infestations, known as myiasis, when used as authorized. The agency said the known and potential benefits of the product outweigh its known and potential risks.
“Today's emergency use authorization provides a new tool for preventing the spread of New World screwworm infestations,” Acting FDA Commissioner Kyle Diamantas said.
How the spray works
CLiK Extra does not kill screwworm larvae directly. Instead, it works as an insect growth regulator, disrupting the development of the larvae and preventing them from completing their life cycle.
The product can be applied to or around a wound when the wound appears or is created.
The authorization covers wounds associated with injuries, birth and surgical or husbandry procedures, including dehorning, ear tagging, castration, tail docking and shearing.
That could give Texas livestock producers another option for protecting animals after procedures that leave them with wounds that could potentially attract screwworm flies.
But the spray is intended for prevention, not treatment of an existing infestation.
If a wound is already infested with screwworm larvae, or if an infestation develops after the product has been applied, the FDA recommends contacting a veterinarian to discuss treatment options.
CLiK Extra is available over the counter for topical use on or around wounds under the terms of the emergency authorization.
Wildlife also included
The FDA's authorization extends beyond agricultural animals.
The product can be used on certain captive and captured wildlife, including cervids such as deer and elk, American bison, bighorn sheep and Sonoran pronghorn.
The agency said protecting wildlife is important because wild animals can also become infested and potentially contribute to the spread of New World screwworm.
“The FDA recognizes that the impact of New World screwworm extends beyond the farm gate,” said Timothy Schell, 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,” said Schell.
For Texas, where livestock and wildlife frequently share the same landscape, the broader authorization could be significant as officials continue to work to contain the outbreak.
Emergency authorization, not full FDA approval
The FDA emphasized that CLiK Extra has not been approved or conditionally approved for any indication so far.
The Emergency Use Authorization is based on the totality of scientific evidence available to the agency. The FDA said it concluded there is reason to believe the product may be effective when used as authorized and that its potential benefits outweigh its potential risks.
The authorization will remain in effect until it is revoked or until the U.S. Department of Health and Human Services secretary terminates the declaration that the potential public health emergency posed by New World screwworm justifies emergency use of animal drugs.
The FDA said its fact sheet for CLiK Extra includes detailed information about how the product should be used, including important food-safety information for livestock.
