A close-up shot of an NWS larva (maggot), with the first one showing its mouth hooks. Photo by the U.S. Department of Agriculture (USDA) The U.S. Food and Drug Administration’s (FDA) Center for Veterinary Medicine (CVM) has issued updated guidance outlining information on conditionally approved or authorized animal drugs used to prevent or treat New World screwworm (NWS; Cochliomyia hominivorax) myiasis. The agency said it is continuing to work with “drug sponsors, federal and state partners, and international regulators to understand options for U.S. veterinarians to treat NWS effectively and safely.” Currently, three animal drugs hold conditional approval for NWS indications: Product Approval Indication(s) Species Freedom of Information (FOI) Dectomax-CA1 (doramectin injection) injectable solution Conditional approval Prevention and treatment of infestations caused by larvae of Cochliomyia hominivorax (myiasis), and prevention of reinfestation for 21 days in cattle. Cattle cNADA 141-616 Exzolt Cattle-CA1 (fluralaner) topical solution* *Extralabel use of this animal drug is not permitted. Conditional approval Prevention and treatment of infestations caused by Cochliomyia hominivorax larvae (myiasis) and treatment and control of cattle fever tick (Rhipicephalus microplus) in beef cattle two months of age and older, and replacement dairy heifers less than 20 months of age. Cattle cNADA 141-617 Credelio Quattro-CA1 (lotilaner, moxidectin, praziquantel, pyrantel) chewable tablets Conditional approval Treatment of infestations caused by Cochliomyia hominivorax larvae (myiasis) in dogs and puppies. Dogs cNADA 141-619 The agency has also authorized several products through Emergency Use Authorizations (EUAs):, Products Indications(s) Species · Credelio (lotilaner) chewable tablets · NexGard (afoxolaner) chewable tablets Treatment of infestations caused by Cochliomyia hominivorax larvae (myiasis) in dogs and puppies. Dogs · Credelio CAT (lotilaner) chewable tablets · NexGard COMBO (esafoxolaner, eprinomectin, and praziquantel topical solution) Treatment of infestations caused by Cochliomyia hominivorax larvae (myiasis) in cats and kittens. Cats Ivomec (ivermectin) injectable solution Prevention of infestations caused by Cochliomyia hominivorax larvae (myiasis) when administered within 24 hours of birth, at the time of castration, or at the appearance of a wound in cattle, except for female dairy cattle producing milk for human consumption and calves that will be processed for veal. Cattle · F10 Antiseptic Wound Spray with Insecticide (benzalkonium chloride, polyhexanide and cypermethrin topical solution)* · F10 Antiseptic Barrier Ointment with Insecticide (benzalkonium chloride, polyhexanide and cypermethrin topical ointment)* *Extralabel use of this animal drug is not permitted. Prevention and treatment of infestations caused by Cochliomyia hominivorax larvae (myiasis) in cattle, horses, minor species of hoof stock, raptors and other wild birds, pet birds, and captive wild, exotic, and zoo mammals. · Cattle · Horses · Minor species of hoof stock · Raptors, wild birds, pet birds · Captive wild, exotic, and zoo mammals Negasunt Powder (coumaphos, propoxur, and sulfanilamide topical powder)* *Extralabel use of this animal drug is not permitted. Prevention and treatment of infestations caused by Cochliomyia hominivorax larvae (myiasis) in cattle, swine, goats, sheep, horses, donkeys, domestic hybrid equids, and captive wild, exotic, and zoo mammals. · Cattle · Swine · Goats · Sheep · Horses · Donkeys · Domestic hybrid equids · Captive wild, exotic, and zoo mammals Dectomax/Dectomax-CA1 (doramectin injection) · Prevention and treatment of infestations caused Cochliomyia hominivorax larvae (myiasis) in dairy cattle (lactating dairy cows, dry dairy cows, replacement dairy heifers, 20 months of age and older) except for calves that will be processed for veal · Prevention of infestations caused by Cochliomyia hominivorax larvae (myiasis) in horses one year and older, swine, sheep except lactating sheep, and deer. · Dairy cattle · Horses · Swine · Sheep · Deer The agency reminded veterinarians that extralabel drug use is permitted only for products with full FDA approval and must comply with federal regulations, including the existence of a valid veterinarian-client-patient relationship. Conditional approvals, index-listed products, and drugs authorized solely under an EUA are not eligible for extralabel use. The FDA said it will continue updating its guidance as additional NWS-related authorizations are issued. For more information, read the agency's Dear Veterinarian Letter: Use of FDA-Authorized Animal Drugs Against New World Screwworm Myiasis. Deer infested with NWS. Photo by the U.S. Department of Agriculture (USDA)
