FDA Explores Animal Drug Options for Screwworm Treatment

Jul 28, 2025
By Farms.com

Efforts Continue to Support Safe Treatment of NWS Cases

The U.S. Food and Drug Administration (FDA) currently has no approved animal drugs to treat or prevent New World Screwworm (NWS) in animals. However, the FDA’s Center for Veterinary Medicine (CVM) is working closely with the USDA, state partners, and international regulators to develop effective solutions.

The NWS is a serious threat to livestock, wildlife, and even pets. It requires safe and effective treatments, especially for food-producing animals. The CVM’s main role is to review data submitted by drug makers to ensure animal health and food safety.

CVM is also partnering with the Environmental Protection Agency (EPA), which regulates certain over-the-counter antiparasitic and insecticide products, to better understand available prevention tools.

Several regulatory pathways can be used to make drugs available quickly, including full FDA approval, supplemental approval, conditional approval, emergency use authorization, and extra-label use. The best option depends on factors such as the drug’s approval status and which animals it treats.

In urgent situations, emergency use or extra-label use may be the fastest way to help animals. Veterinarians are allowed to prescribe FDA-approved drugs for off-label use if they have a valid relationship with their clients and follow existing laws.

CVM is also looking at long-term safety and effectiveness, and the potential for drug resistance. The agency encourages drug companies to submit research and explore possible approval routes.

Video: Season 7, Episode 6: Using Competitive Exclusion to Reduce E. coli in Weaned Pigs

Newly weaned pigs are especially vulnerable to pathogenic E. coli, which can cause diarrhea and other health challenges. Research is exploring how introducing beneficial bacteria before exposure to harmful bacteria could help reduce the severity of post-weaning disease, with timing playing an important role.

Dr. Marcelo Almeida, assistant professor in Iowa State University’s College of Veterinary Medicine, and Dr. Rodrigo Paiva, graduate student and pathology resident at the Iowa State University Veterinary Diagnostic Laboratory, discuss their research on competitive exclusion in weaned pigs. They explain how this approach works, why introducing beneficial microorganisms before E. coli exposure may improve outcomes and what they learned about diarrhea, E. coli shedding and pig performance. The conversation also explores the potential to address antimicrobial resistance and the considerations for applying these findings in commercial pork production.