Action Prepares Veterinarians and Livestock Producers with Prevention and Treatment Options Prior to Fly Being Detected in the U.S.

• Federal agencies grant emergency authorizations for New World screwworm in livestock, reinforcing Elanco's leadership in livestock health innovations  
• Actions underscore the commitment of the U.S. Food and Drug Administration, U.S. Environmental Protection Agency, and U.S. Department of Agriculture to act swiftly against emerging animal health threats 
• Early detection and immediate treatment of open wounds on livestock is critical to prevention of New World screwworm myiasis in individual animals and rapid spread of the pest
• An effective fly and tick control regimen is also essential, helping to avoid small bites on animals that can be an entry point for the screwworm

INDIANAPOLIS , April 27, 2026 /PRNewswire/ -- Elanco Animal Health Incorporated (NYSE: ELAN) announced it has received Emergency Use Authorization (EUA) from the U.S. Food and Drug Administration (FDA) for Negasunt Powder (coumaphos, propoxur, sulfanilamide topical powder) and a Section 18 Emergency Exemption from the U.S. Environmental Protection Agency (EPA) in cooperation with the United States Department of Agriculture (USDA) for Tanidil (coumaphos, propoxur) for the prevention and treatment of New World screwworm infestations in a variety of livestock species.

With confirmed cases of New World screwworm detected as close as 62 miles south of the U.S.-Mexico borderⁱ, these authorizations ensure veterinarians and livestock producers have a ready-now treatment option for various livestock species should the fly enter the U.S.

Negasunt Powder and Tanidil will be available only through the U.S. Animal Plant Health and Inspection Service (APHIS) and its National Veterinary Stockpile. They will be distributed in coordination with state animal health officials and federally recognized tribal agencies. In the near future, APHIS will share additional information about the requirements for use, including tracking and reporting requirements and required safety and personal protective equipment.

With more than 70 years of on-farm experience, Elanco is standing alongside livestock producers and regulators during this challenging time by providing New World screwworm options for prevention and treatment of New World screwworm infestations, education and science-based resources if the fly enters the U.S.

"We appreciate our federal agencies' swift review of the scientific data demonstrating that these products may be effective in prevention and treatment against New World screwworm infestations," said Dr. Ellen de Brabander, Executive Vice President of Research & Development at Elanco. "We're committed to working alongside state and federal regulatory authorities to provide our support and scientific expertise. These emergency authorizations provide new, science-based solutions and treatment options to livestock producers, veterinarians, and other animal health industry stakeholders at a time when they need them most."

Effective Parasite Protection is Paramount

Elanco now offers producers and veterinarians several key products that can help prevent and treat New World screwworm infestations in a variety of livestock species. In addition to the EUA for Negasunt Powder and the Section 18 Emergency Exemption for Tanidil, the company also offers Catron IV – one of the few EPA registered products labeled for treatment against screwworm in a variety of livestock species. This screwworm and ear tick spray can help producers kill and control screwworm flies and maggots on beef and dairy cattle, sheep, goats, hogs and horses.

"The most important thing producers can do is self-education. They should be learning more about New World screwworm from credible sources, staying current with treatment protocol recommendations, and knowing where active cases are located," said Dr. M. Wayne Ayers, Elanco Sr. Technical Consultant and veterinarian. "The second most important part of preventing losses from New World screwworm is for producers to keep their 'eyes on livestock.' Looking over livestock as frequently as possible will allow early detection and treatment of infestation. Early intervention is key to minimizing tissue damage, decreasing mortality, and reducing the risk to the area by preventing the fly's potential offspring from completing their lifecycle."

Preventing Wound-Causing Parasites Also Essential

According to APHIS, an important way to prevent New World screwworm infestation is to protect livestock from other wound-causing parasites such as biting flies and ticks._ii

"Some of the surgical and care procedures we perform for livestock could result in potential sites for the female screwworm to deposit her eggs," said Dr. Ayers. "Wounds as small as fly and tick bites are potential areas to watch for as well. Therefore, treating open wounds, including those from surgical sites, and instituting a good fly and tick prevention program will play an important role in reducing the number of infestations we may see."

Elanco offers several EPA registered products to help control flies and ticks on livestock in the forms of pour-on liquids, sprays, dusts and ear tags.

Elanco recommends that livestock producers and veterinarians review the latest resources available from the USDA and FDA and consider the additional resources below in advance of the potential entry of New World screwworm into the United States.

To learn more about New World screwworm (NWS) using the following resources:

• USDA NWS Alert and Fact Sheet
• NCBA NWS Resources
• FDA Information for Veterinarians on NWS

Emergency Use Authorization of Negasunt Powder (coumaphos, propoxur, and sulfanilamide topical powder) for New World Screwworm (NWS)

WARNING: Neurotoxicity. Read full Fact Sheet for complete information. 

• Coumaphos and propoxur can cause neurotoxicity. May be fatal if swallowed. May be fatal if inhaled. Harmful if absorbed through skin. Causes moderate eye irritation. Do not breathe dust. Avoid contact with eyes, skin, or clothing.  
• Use only with appropriate personal protective equipment (PPE): coveralls worn over long-sleeve shirt and long pants, shoes, socks, and protective eyewear; chemical-resistant gloves made of  barrier laminate, butyl rubber (≥ 14 mils), nitrile rubber (≥14 mils), neoprene rubber (>14 mils), natural rubber (≥14 mils), polyethylene, polyvinyl chloride (PVC) ≥14 mils, or Viton (>14 mils); and a minimum of a NIOSH-approved elastomeric half mask respirator consisting of protection factor (PF) 10 fitted with organic vapor (OV) cartridges and combination  R or P filters; or a NIOSH-approved gas mask with OV canisters; or a NIOSH-approved powered air purifying respirator with OV cartridges and combination HE filters.  
• This product is toxic to mammals, birds, fish, and aquatic invertebrates. 

The U.S. Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) for the emergency use of the unapproved product Negasunt Powder for the prevention and treatment of infestations caused by New World screwworm (Cochliomyia homnivorax) larvae (myiasis) in cattle, swine, goats, sheep, horses, donkeys, domestic hybrid equids, and captive wild, exotic, and zoo mammals. Negasunt Powder is not approved for this use.

For use by employees of federal, state, local, and federally recognized tribal agencies, and persons working under their authority and at their direction. Also for use by or on the order of a licensed veterinarian in NWS infested zones and adjacent surveillance zones as defined by the U.S. Department of Agriculture (USDA). 

For additional information on the EUA and for complete safety information, please refer to the Negasunt Powder NWS Fact Sheet.  

Limitations of Authorized Use  
It is a violation of federal law to use this drug product other than as directed in the authorized Fact Sheet. 

Treated animals must not be slaughtered for human consumption within 28 days of the last treatment. 

A milk discard time has not been established for this product; do not use in animals producing milk for human consumption. 

A withdrawal period has not been established for this product in pre-ruminating calves; treated calves and calves born to treated cows must not be processed for veal. 

Do not use in horses intended for human consumption. Do not use in domestic indoor pets (e.g., dogs, cats, rodents, rabbits) nor in residences. Do not use in birds. Do not use in free-ranging wildlife. 

To avoid overexposure, each individual person cannot treat more than 3 large wounds (>2 inches diameter) a day or more than 30 small superficial wounds (≤2 inches diameter) a day (or an equivalent thereof) with Negasunt Powder or any other coumaphos-containing products.  

Negasunt Powder is authorized for this use only for the duration of the declaration that circumstances exist justifying the authorization of the emergency use of Negasunt Powder under section 564(b)(1) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 21 U.S.C. § 360bbb-3(b)(1), unless the declaration is terminated or the authorization is revoked sooner. 

Federal law prohibits the extra-label use of this drug. 

Additional Important Safety Information
Not for use in humans. Keep out of reach of children. Only handlers wearing required PPE may be in the area during application.  Do not apply in a confined, non-ventilated area; provide thorough ventilation. Call a poison control center or doctor immediately for treatment advice if Negusant Powder is swallowed, inhaled, on skin or clothing, or in eyes. Sulfonamides are contraindicated in animals that are hypersensitive to them and in animals with severe renal or hepatic impairment. For external use only on animals.  Do not contaminate water, feed, troughs, feed handling equipment, or milk or meat handling equipment. Use with caution in very young, weak, or debilitated animals.  In the case of overdose, treat with atropine sulfate or pralidoxine chloride (2-PAM) as soon as possible. The most common adverse reactions associated with organophosphate and carbamate toxicity in animals include frequent urination and defecation, muscle twitching, and watering eyes.

Important Information about Tanidil
Tanidil™ is an unregistered product for distribution and use only under a Section 18 emergency exemption. The Section 18 labeling must be in the possession of the user at the time of pesticide application.  This product may only be used to prevent or control New World screwworm in and on animal wounds on labeled animal host species.

For use only by federal, state, local, and federally recognized tribal agencies, and persons working under their supervision; personnel at quarantine stations and areas; veterinarians; veterinarians or certified applicators at livestock and game facilities, zoos, wildlife facilities, animal rehabilitation centers; and wildlife professionals. 

Read the entire label. This product must be used strictly in accordance with this label's precautionary statements and use directions, as well as with all applicable state and federal laws and regulations. Please visit the Tanidil fact sheet for more information.

Use Period: This exemption is effective on April 27, 2026 and expires on April 27, 2029. No applications of Tanidil may be made under the emergency exemption before its effective date or after its expiration date.  

ABOUT ELANCO
Elanco Animal Health Incorporated is a global leader in animal health dedicated to innovating and delivering products and services to prevent and treat disease in farm animals and pets, creating value for farmers, pet owners, veterinarians, stakeholders and society as a whole. With 70 years of animal health heritage, we are committed to breaking boundaries and going beyond to help our customers improve the health of animals in their care, while also making a meaningful impact on our local and global communities. At Elanco, we are driven by our vision of Food and Companionship Enriching Life and our purpose – all to Go Beyond for Animals, Customers, Society and Our People. Learn more at www.elanco.com.

Media Contact: Season Solorio (765) 316-0233 season.solorio@elancoah.com
Investor Contact: Tiffany Kanaga (765) 740-0314 tiffany.kanaga@elancoah.com

Negasunt, Tanidil, Catron, Elanco and the diagonal bar logo are trademarks of Elanco or its affiliates. © 2026 Elanco or its affiliates.

 

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