New World Screwworm Outbreak: What Dog Owners Need to Know
New World screwworm has returned to animals in the United States. The current risk remains very low for most dogs, but owners should know what an infestation looks like and when a wound needs immediate veterinary attention.
A parasite the United States wiped out decades ago is back, infecting animals here at home again.
New World screwworm has been in the news following confirmed detections in U.S. animals, including a dog case in New Mexico. “Flesh-eating parasite” is the kind of phrase that grabs headlines, and I understand why it sounds scary.
But this calls for paying attention, not panicking.
Federal officials currently describe the overall risk to people and animals in the United States as very low. Still, an infestation can cause serious and potentially fatal injuries if it isn't treated, so knowing the warning signs and getting veterinary care quickly matters.
For dog owners, the real question isn't whether to be scared of every scrape your dog gets.
It's knowing what to look for and when to pick up the phone.
What's Actually Happening?
New World screwworm (Cochliomyia hominivorax) is a parasitic fly the United States eradicated decades ago through a massive sterile-fly control program.
So when it started showing up in animals here again, officials took notice.
The U.S. Department of Agriculture confirmed the first U.S. animal case associated with the current outbreak on June 3, 2026 — a calf in Zavala County, Texas.
Five days later, USDA announced another confirmed case involving a dog. The sample was submitted by a veterinarian in Andrews County, Texas, which initially led the case to be reported there.
USDA later clarified that the dog lived in Lea County, New Mexico, making it the first confirmed New World screwworm case in New Mexico during the current outbreak. By that point, Texas alone had already confirmed multiple cases beyond its first.
The outbreak has continued since then. State and national veterinary organizations tracking the case count reported 15 confirmed cases across Texas and New Mexico by June 22, 2026, and 42 confirmed cases by July 24, 2026. USDA has also continued adjusting the boundaries of its "infested zones" — the areas around confirmed detections subject to enhanced surveillance and animal-movement controls — as new cases are confirmed or resolved, including a modification and expansion of infested zones in Texas on September 4, 2026.
Federal and state officials have continued surveillance, response efforts, sterile-fly operations and animal-movement controls intended to stop the parasite from becoming established more broadly.
Because this situation is still changing, check the USDA New World screwworm current-status page and its confirmed detections dashboard for the latest verified case count and affected areas, rather than relying on older case counts shared in news reports or on social media — including the counts in this article, which reflect research current as of September 15, 2026.
Why New World Screwworm Is Dangerous
Finding maggots on your dog is upsetting regardless of what's causing them.
New World screwworm larvae are especially dangerous because they feed on healthy, living tissue.
Female flies can lay eggs in or around wounds and mucous membranes. After the eggs hatch, the larvae burrow into the tissue and continue feeding.
That means something that starts around a relatively small wound can become much more serious.
Warning Signs to Watch For
The warning signs are practical things dog owners can actually look for. They may include:
- Visible larvae or maggots in a wound or body opening
- A wound that's becoming larger or deeper
- A foul or unusual odor
- Irritation or obvious discomfort around an affected area
- Your dog repeatedly licking or bothering one location
- Changes in behavior as an infestation becomes more severe
The U.S. Food and Drug Administration advises owners to seek immediate veterinary care if a dog has visible maggots or a foul odor around wounds or body openings such as the eyes, ears, nose or mouth.
You don't have to be the one who diagnoses it.
That's what your veterinarian is for.
This Isn't Just a Cattle Problem
A lot of New World screwworm coverage focuses on cattle and agriculture, which makes sense considering the threat the parasite poses to livestock.
But dogs can become infested too.
New World screwworm can affect many warm-blooded animals, including pets, livestock, wildlife and, in rare cases, people.
For dog owners, wounds deserve particular attention.
A cut, surgical incision, irritated skin or another opening can provide a place where flies may lay eggs.
That doesn't mean every little scratch is suddenly an emergency.
It means good wound care matters.
What Should Dog Owners Actually Do?
For most dog owners, daily life doesn't need to change dramatically.
What's worth doing is making basic wound checks part of normal care.
When you're petting your dog, brushing him or checking his paws after a walk, take a second to notice whether there is a new cut, irritated skin or a spot he keeps returning to.
If your dog recently had surgery or already has a wound being treated, follow your veterinarian's instructions and keep watching the area for changes.
Dogs that live in, travel through or return from areas where New World screwworm has been identified deserve additional attention.
See maggots in a wound?
Don't wait several days hoping the problem clears up on its own. Call your veterinarian.
What About Florida?
For Florida dog owners, here's where things currently stand:
New World screwworm has not been detected within Florida, according to the Florida Department of Agriculture and Consumer Services.
Florida has nevertheless put an emergency rule in place that currently bars rescue dogs, rescue cats, shelter dogs and shelter cats originating from states with confirmed New World screwworm detections from entering Florida "until further notice." Additional movement requirements also apply to animals coming from designated infested zones and certain high-risk areas.
The state has good reason to be cautious.
In 2016, New World screwworm appeared in the Florida Keys and severely affected endangered Key deer before federal and state agencies eliminated the outbreak.
Today, Florida requires additional documentation and veterinary inspection in certain circumstances for animals entering the state from affected areas. These requirements can change as the outbreak develops, so don't assume today's rules will still apply next month.
You can check the current Florida dog and cat movement requirements before traveling or transporting an animal into the state.
For dog owners in Miami, Fort Lauderdale, Tampa or elsewhere in Florida, the practical response remains straightforward:
Stay informed, monitor wounds and check the latest movement requirements if you're bringing a dog into Florida from an affected area.
Is There Treatment for Dogs?
Yes.
The FDA has expanded access to veterinary treatment options for New World screwworm.
But the terminology matters.
As of September 15, 2026, the FDA says there are no drugs with full FDA approval specifically for New World screwworm myiasis.
Instead, several medications are available through conditional approval or Emergency Use Authorization.
For dogs, FDA currently lists:
- Credelio Quattro-CA1 — conditionally approved to treat New World screwworm infestations in dogs and puppies (December 17, 2025)
- NexGard — authorized under an Emergency Use Authorization for treatment in dogs and puppies (February 18, 2026)
- NexGard COMBO — authorized under an Emergency Use Authorization for treatment in dogs and puppies (February 18, 2026)
- Simparica TRIO — authorized under an Emergency Use Authorization for treatment, not prevention, in dogs and puppies (August 13, 2026)
- Generic nitenpyram — authorized under an Emergency Use Authorization for treatment in dogs and puppies (June 11, 2026)
- Capstar — authorized under an Emergency Use Authorization for treatment in dogs and puppies (September 3, 2026)
An earlier standalone Emergency Use Authorization for plain Credelio (lotilaner) in dogs is no longer listed separately on FDA's current authorization page; Credelio Quattro-CA1 is the product FDA currently lists for dogs under that brand name.
Simparica TRIO's emergency authorization is for treatment, not prevention, of New World screwworm.
That distinction is important.
Just because your dog already takes one of these products for fleas, ticks, heartworms or another parasite does not automatically mean your dog is protected against New World screwworm.
Talk with your veterinarian about what is appropriate for your dog.
Can People Get New World Screwworm Too?
Yes.
New World screwworm can infest people, although human cases are considered rare in the United States.
The Centers for Disease Control and Prevention currently says the risk to the general U.S. public is very low and reports no locally acquired human infestations during the current U.S. outbreak. The one confirmed U.S. human case connected to this outbreak, reported in August 2025, was travel-associated in a person who had visited El Salvador.
This is another place where headlines can outrun the actual risk.
New World screwworm deserves serious attention because of the damage an infestation can cause.
That doesn't mean the average dog owner should live as though an infestation is likely.
The Best Thing You Can Do
Look at your dog.
We already do this constantly without thinking much about it.
We scratch behind their ears. We rub their bellies. We check their paws after walks. We notice when they're licking the same spot over and over.
Those everyday moments are exactly when you might catch something new:
A wound that's changing.
A smell that wasn't there before.
A spot your dog won't leave alone.
Or something moving inside a wound that clearly shouldn't be there.
Most of the time, it won't be New World screwworm.
But if something looks wrong, getting your veterinarian involved quickly is better than trying to diagnose or treat it yourself.
Dog owners don't need to panic over every scrape. Pay attention to wounds, watch for visible larvae, worsening tissue or unusual odors, and contact your veterinarian promptly if something looks wrong.
For a deeper look at symptoms, treatment, prevention, wound checks and risk factors, read our complete Screwworm in Dogs: Symptoms, Treatment & Prevention .
Sources & Further Reading
- USDA APHIS — Current Status of New World Screwworm
- USDA APHIS — Confirmed Detections of New World Screwworm (dashboard)
- U.S. Food and Drug Administration — Animal Drugs for New World Screwworm
- Centers for Disease Control and Prevention — New World Screwworm Situation Summary
- Florida Department of Agriculture and Consumer Services — New World Screwworm
- Florida Dog and Cat Movement Requirements
- American Animal Hospital Association — New World Screwworm Updates and Resource Roundup
