US Braces for Flesh-Eating Parasite With Emergency Pet Treatments

DULUTH, GA – February 19, 2026 – In a significant move to defend against a gruesome and advancing biological threat, the U.S. Food and Drug Administration (FDA) has granted Emergency Use Authorizations (EUA) for two widely used pet medications to treat infestations of the New World screwworm. The authorizations for Boehringer Ingelheim’s NexGard® for dogs and NexGard® COMBO for cats come as the flesh-eating parasite, eradicated from the United States decades ago, spreads northward through Mexico, with recent cases detected less than 70 miles from the Texas border.

This proactive measure provides veterinarians, particularly in southern border states, with readily available and federally authorized tools to combat a parasite that poses a grave danger to pets, livestock, wildlife, and even humans. The decision underscores a heightened state of alert as federal and state agencies work to prevent the re-establishment of a pest that once cost the American livestock industry hundreds of millions of dollars annually.

"Preparedness isn't optional when it comes to emerging animal health threats," said Daniel Watkins, Head of U.S. Pet at Boehringer Ingelheim, in a statement. "Readiness matters. These authorizations ensure veterinarians have access to treatment options the moment they are needed."

The Looming Threat of a Resurgent Parasite

The New World screwworm, Cochliomyia hominivorax (Latin for “man-eater”), is a parasitic fly with a particularly horrifying life cycle. Unlike other flies that lay eggs in decaying matter, the female screwworm fly seeks out open wounds on warm-blooded animals—anything from a small tick bite to a surgical incision or the navel of a newborn calf. She lays hundreds of eggs, which hatch into larvae that do not feed on dead tissue but burrow directly into and consume healthy, living flesh.

Infestations are rapid, destructive, and often fatal if not treated. The growing mass of burrowing larvae creates a larger wound that emits a foul odor, attracting more female flies to lay more eggs. This devastating cycle was once a grim reality for ranchers across the southern United States until a groundbreaking program led to its eradication in 1966. That effort relied on the Sterile Insect Technique (SIT), which involves releasing billions of sterilized male flies to mate with wild females, causing the population to collapse. A permanent biological barrier of sterile flies has since been maintained in Panama to prevent re-entry from South America.

However, that barrier was breached in 2023, leading to an outbreak that has swept through Central America and Mexico. As of early 2026, the outbreak has caused over 153,000 animal cases and more than 1,300 human cases across the region. The northward march of the parasite is a cause for serious alarm, with a confirmed case in Nuevo León, Mexico, placing the threat squarely at the doorstep of the United States.

A Proactive Defense: Inside the FDA's Emergency Response

The FDA’s action is a direct response to this escalating risk. An Emergency Use Authorization, issued under Section 564 of the Federal Food, Drug, and Cosmetic Act, allows the use of unapproved medical products or unapproved uses of approved products during a public health emergency. In this case, it allows NexGard® Chewables (afoxolaner) for dogs and NexGard® COMBO (esafoxolaner, eprinomectin, and praziquantel topical solution) for cats to be prescribed specifically for the treatment of NWS infestations.

While these products are already FDA-approved and widely used for controlling common parasites like fleas and ticks, they had not been approved for this specific, exotic threat. The EUA bridges that gap, giving veterinarians a clear, legal, and effective protocol to follow the moment a case is suspected. This rapid regulatory action is a key component of the national preparedness strategy, ensuring that a lack of approved treatments does not become a weak link in the nation's biosecurity chain.

The authorized drugs are available only by, or on the order of, a licensed veterinarian. This ensures proper diagnosis and administration while helping officials track potential cases. The authorization is temporary and will only last as long as the official declaration of emergency is in effect.

Fortifying the Border and Preparing the Front Lines

The new EUAs are one part of a multi-faceted defense strategy. The U.S. Department of Agriculture (USDA) is working closely with Mexican authorities on a collaborative action plan that includes enhanced surveillance, trapping, and animal movement controls. All southern ports of entry were temporarily closed to livestock trade and have only recently reopened under stringent pre-clearance inspection and treatment protocols.

The cornerstone of the long-term defense, the Sterile Insect Technique, is also being massively reinforced. The USDA is investing millions to upgrade a facility in Mexico to significantly increase the weekly production of sterile flies, which are being dispersed in targeted areas to halt the parasite's northward advance.

On the ground, veterinarians are considered the frontline defenders. They are being urged to be vigilant for signs of NWS, which can be mistaken for a simple infected wound. The AVMA and USDA are providing resources to help veterinarians diagnose infestations and reminding them that NWS is a reportable disease, requiring immediate notification to state and federal animal health officials.

"Screwworm infestations can escalate quickly, and treatment delays put animals at real risk," noted Steve Maschmedt, Executive Director of Pet Veterinary Technical Services at Boehringer Ingelheim. He also stressed the importance of preventative care, adding, "Routine flea and tick control helps minimize skin irritation and small bite-related wounds, which can otherwise create opportunities for NWS flies to lay eggs."

This highlights a crucial message for pet owners: diligent wound care and regular parasite prevention are now more important than ever, serving as a first line of defense against a potentially devastating invader. This proactive stance, from federal agencies down to individual pet owners, serves as a critical blueprint for confronting the complex and interconnected animal health challenges of the 21st century.