New World Screwworm Alert: CDC, FDA Fast-Track Drug Access to Curb Spread

Federal health authorities in the United States are stepping up efforts to contain the New World screwworm, a flesh-eating parasite that has recently been detected in livestock in southern Texas and parts of New Mexico. While the parasite primarily affects animals, health experts say it can also infect humans under certain conditions, prompting the U.S. Centers for Disease Control and Prevention (CDC) and the US Food and Drug Administration (FDA) to launch an aggressive response. The CDC has activated its Emergency Operations Center to coordinate surveillance, prevention, and response activities alongside the U.S. Department of Agriculture (USDA) and state health authorities. Although the risk to the general public remains low, officials are urging

veterinarians, healthcare providers, and animal owners to remain vigilant.Also read: 3 Cataract Myths That Could Cost You Your Vision, Eye Doctor Warns

What is the new world screwworm?

The New World screwworm is the larval stage of a fly (Cochliomyia hominivorax) that lays eggs in open wounds or natural body openings of warm-blooded animals. Within hours, the eggs hatch into larvae that burrow into healthy, living tissue, causing a painful condition known as myiasis. Unlike many parasites that feed on dead tissue, screwworm larvae consume living flesh, making infestations particularly destructive if left untreated. The parasite mainly threatens:

• Cattle
• Sheep
• Goats
• Horse
• Dogs and cats
• Wildlife

Although human infections are uncommon, they can occur if flies lay eggs in untreated wounds or body openings.

Current situation in the US

According to the USDA, as of June 11, 12 cases of New World screwworm have been confirmed in domestic animals, including cattle, goats, and sheep, in southern Texas and one county in New Mexico. Importantly, the CDC says no human cases have been reported in the United States during the current outbreak. Officials also emphasized that the parasite does not spread from person to person or from infected animals to humans. Infection occurs only when an adult fly directly deposits eggs into an open wound or body opening.

FDA authorizes first generic treatment for pets

In a significant move to strengthen outbreak control, the FDA has issued an Emergency Use Authorization (EUA) for the first generic treatment targeting New World screwworm infestations in companion animals. The approved medication is generic nitenpyram tablets, which can be used in dogs, puppies, cats and kittens.The tablets are available over the counter and are dosed according to the animal's body weight. The medication works rapidly, killing most screwworm larvae within hours. Pet owners are instructed to administer a second dose six hours after the first to maximize effectiveness. However, experts caution that the medication does not remove dead larvae or prevent future infestations. Veterinary care remains essential for proper wound cleaning, removal of remaining larvae, and monitoring for secondary infections. The FDA also advises against using the drug in animals weighing less than two pounds or younger than four weeks of age.

How to protect pets and livestock

Health officials recommend several preventive measures:

• Regularly inspect animals for cuts, wounds, or unusual swelling.
• Clean and treat wounds promptly.
• Seek veterinary care if maggots or unusual tissue damage are noticed.
• Keep animal housing clean and reduce fly exposure.
• Report suspected screwworm cases immediately to animal health authorities.

Should humans be concerned?

While the current public health risk remains low, experts stress that awareness is important, especially for people working with livestock or animals in affected regions. The US successfully eradicated New World screwworm decades ago, and officials are confident they can do so again through rapid surveillance, prompt treatment, and coordinated public health action. Early detection, responsible wound care, and timely veterinary intervention remain the best defences against this destructive parasite.