FDA Grants Emergency Use of Wound Spray as Texas Screwworm Fight Gains a Second Drug

Ranchers fighting the New World screwworm outbreak in Texas woke up Saturday with something they haven't had much of this summer: a new option. The U.S. Food and Drug Administration on Friday issued an Emergency Use Authorization for CLiK Extra, a dicyclanil-based wound spray made by Elanco, clearing it for use on or around wounds to prevent screwworm infestations in cattle, horses, sheep, goats, swine, and even captive and captured wildlife.

The authorization makes CLiK Extra the second drug the FDA has rushed into the screwworm fight this year. In late April, the agency granted emergency use of Negasunt Powder, an organophosphate-based topical treatment, as the parasite pushed toward the border. That threat has since become reality — officials have confirmed 45 infestations this summer, nearly all of them in Texas, with 22 counties under livestock movement restrictions and the State Operations Center activated to coordinate the response.

Why a wound spray matters

Screwworm flies don't attack healthy tissue. Females lay eggs in open wounds — branding cuts, barbed wire scrapes, tick bites, even navels of newborn calves — and the hatching larvae eat living flesh. A product applied directly to those wounds breaks the cycle at its entry point.

Dicyclanil, the active ingredient in CLiK Extra, works differently than the insecticides in Negasunt. It's an insect growth regulator: rather than killing larvae outright, it disrupts their development so they never mature. The CLiK line has a long track record overseas, where sheep producers have used dicyclanil pour-ons for years to prevent blowfly strike — a close cousin of screwworm myiasis. The emergency authorization adapts that chemistry to the crisis at hand.

Miller: "Don't confuse treatment with eradication"

Texas Agriculture Commissioner Sid Miller welcomed the news in a statement Friday, thanking the FDA, the Department of Health and Human Services, and Secretary Robert F. Kennedy Jr. for moving quickly. But he paired the praise with a warning that has defined his posture all summer.

"Every new weapon we can put in the hands of those on the front lines strengthens our ability to defend American agriculture," Miller said. "But let's not confuse treatment with eradication. The only proven way to eliminate this pest is to destroy the fly itself."

Miller has spent months pressing Washington to adopt the SWASS strategy — an aggressive sterile-fly campaign he argues is the only path to pushing the screwworm back across the border permanently. The USDA is currently scaling sterile fly production at facilities in Texas and Arizona, but capacity remains a fraction of what eradication models call for.

What producers should know

The EUA covers prevention, not treatment of active infestations — animals already carrying larvae still need veterinary attention and mandatory reporting to the Texas Animal Health Commission. Producers in the 22-county restricted zone should continue pre-movement inspections regardless of spray use.

With 45 cases on the books and the peak heat of August favoring fly activity, the timing is not accidental. Federal and state officials are clearly stocking the toolbox while the longer eradication game plays out.