The biggest cat-worm development in September 2026 is an emergency authorization for over-the-counter nitenpyram against New World screwworm myiasis. New studies also show that familiar intestinal parasites remain common, especially among kittens and free-roaming cats.
These findings point to two separate concerns: an urgent wound infestation caused by fly larvae and routine intestinal infections detected through fecal testing. Most U.S. cats face low screwworm risk, but ordinary parasite prevention still matters.
Table of Contents
- What changed for New World screwworm?
- Screwworm is not an intestinal worm
- How common are intestinal parasites?
- Which cats face the greatest risk?
- What should cat owners do now?
What changed for New World screwworm?
On September 3, the FDA authorized Capstar and generic nitenpyram products to prevent and treat New World screwworm myiasis. The authorization covers cats and kittens at least four weeks old that weigh two pounds or more. It is the first FDA authorization that includes preventing this infestation in pets, according to the FDA emergency-use announcement.
This is an emergency-use authorization, not a broad recommendation that every cat needs nitenpyram. Owners should confirm that a cat meets the age and weight requirements and follow the authorized product directions. The FDA had issued 15 emergency-use authorizations and three conditional animal-drug approvals related to New World screwworm by September 3. Those actions reflect a focused response to a specific parasite threat rather than a change in routine treatment for intestinal worms.
Screwworm is not an intestinal worm
New World screwworm is a parasitic fly, despite its name. Its larvae infest wounds and consume living tissue, producing a dangerous condition called myiasis. Most cats in the United States remain at low risk.
Cats living in or returning from confirmed areas need closer observation, according to the FDA's September guidance for pet owners. Seek immediate veterinary care if an at-risk cat has: A suspected infestation is not a wait-and-see problem. A veterinarian can assess the wound, remove affected material when appropriate, and determine how an authorized drug fits into treatment.
- Maggots in or around a wound
- A wound with a foul smell
- An apparent infestation in damaged skin
How common are intestinal parasites?
A newly published U.S. analysis found parasites in 13.52% of 15,395 feline fecal examinations. Giardia was detected in 4.82%, while the roundworm Toxocara cati appeared in 4.75%. The authors said the results support comprehensive fecal testing and year-round parasite protection, as reported in Veterinary Parasitology.
That percentage should not be treated as the infection rate for every U.S. cat in 2026. Researchers examined samples submitted to Zoetis laboratories during 2023, rather than a random sample of the current national cat population. Positivity also varied significantly by age, region, sex, reproductive status, and month. The practical lesson is that appearance alone cannot establish a cat's risk; testing gives a veterinarian more useful evidence.
Which cats face the greatest risk?
Free-roaming cats can carry a much heavier parasite burden. Researchers found parasites in 57.5% of 87 free-roaming New York City cats, including Toxocara in 54%. Young males shed significantly more eggs than other cats in that study. A Portuguese study reached a similar risk-based conclusion.
It found intestinal parasites in 42.6% of 345 cats, with stray cats having 4.5 times the infection odds of pets. Kittens younger than six months also had elevated risk, and Toxocara cati was the leading helminth at 30.3%. These studies examined specific groups and locations, so their percentages do not apply automatically to every household cat. They do show why parasite surveillance and treatment are useful during trap-neuter-return work and why kittens and newly adopted strays deserve prompt veterinary assessment.
What should cat owners do now?
Match the response to the type of parasite concern. Screwworm demands urgent wound evaluation, while intestinal parasites call for planned testing and veterinarian-directed prevention.
Practical next steps include: The FDA also finalized revised international guidance in June 2026 on how drug sponsors should demonstrate that feline dewormers work. The guidance strengthens cat-specific evidence requirements, but it does not create a new treatment recommendation for an individual pet.
- Check cats returning from confirmed screwworm areas for wounds, maggots, and foul odors.
- Seek veterinary care immediately if suspected larvae appear.
- Arrange fecal testing based on the veterinarian's recommended schedule.
- Discuss year-round protection, especially for kittens, outdoor cats, strays, and cats entering multi-cat homes.
- Include parasite screening and treatment planning in trap-neuter-return programs.