A flesh-eating parasitic fly has established itself in southern Texas and New Mexico, and the federal government's response now spans three agencies, a Level 3 emergency declaration, and the first-ever FDA-authorized over-the-counter treatment for the parasite in domestic pets.
The U.S. Centers for Disease Control and Prevention's Level 3 Emergency Operations Center remains active as of June 16–17, 2026, coordinating the response alongside the U.S. Department of Agriculture, Texas health and agriculture officials, and the Food and Drug Administration. According to HealthDay reporting confirmed June 16, 2026, 12 cases of New World screwworm (NWS) have been confirmed in domestic animals — including sheep, cattle, and goats — in southern Texas and one county in New Mexico, with the USDA conducting aerial releases of sterile insects as the primary biological containment strategy.
For pet owners in affected and neighboring areas, the most immediately actionable development is the FDA's June 11, 2026 Emergency Use Authorization for generic Nitenpyram Tablets — the first animal drug ever authorized specifically to treat NWS myiasis in dogs, puppies, cats, and kittens.
What the FDA Authorized — Nitenpyram, How It Works, and How to Use It
According to the FDA's press announcement, the authorized product — generic Nitenpyram Tablets sponsored by Felix Pharmaceuticals Pvt. Ltd. of Ireland — is available over the counter in two tablet sizes: 11.4 mg and 57 mg. Dosing is based on the animal's body weight. The drug is approved for use in animals that weigh at least two pounds and are at least four weeks old.
Nitenpyram works quickly. As reported by HealthDay, the drug kills most larvae within hours of the first dose. Pet owners must administer a second dose six hours after the first for complete effect. Critical limitations exist:
- Nitenpyram kills larvae but does not physically remove them — a veterinarian may still need to manually extract larvae that remain in the wound after treatment
- The drug is short-acting and does not prevent future infestations — it only treats active infestation
- It should not be given to pets weighing less than two pounds
- Package insert guidance should be reviewed for pregnant or nursing animals and for co-administration with other products
"Generic animal drugs build resilience in our domestic supply chain and play a critical role in expanding the toolkit of U.S. veterinary drugs for New World screwworm," said Timothy Schell, director of the FDA's Center for Veterinary Medicine, in the agency's statement.
As Fox Weather reported, Acting FDA Commissioner Kyle Diamantas noted: "The FDA has spent nearly a year fast-tracking reviews and readying for the arrival of New World screwworm in the U.S. As of today, the FDA has issued ten EUAs and three conditional approvals for drugs to combat this threat, and this count will continue to grow."
| New World Screwworm Response — Key Data (as of June 16–17, 2026) | Detail |
| Confirmed U.S. animal cases | 12 (sheep, cattle, goats — southern TX and one NM county) |
| CDC Emergency Operations Center | Level 3 (actively coordinating) |
| FDA EUA issued | June 11, 2026 |
| Drug authorized | Generic Nitenpyram Tablets (EUA 006661) |
| Manufacturer | Felix Pharmaceuticals Pvt. Ltd., Ireland |
| Eligibility (pets) | Dogs, puppies, cats, kittens ≥2 lbs and ≥4 weeks old |
| Tablet sizes available | 11.4 mg and 57 mg (weight-based dosing) |
| How quickly it kills larvae | Most larvae killed within hours of first dose |
| Second dose required | Yes — 6 hours after first dose |
| Does it prevent future infestations? | No — short-acting; treatment only |
| Larvae removal after treatment | May still require veterinary removal |
| Total FDA NWS drug authorizations | 10 EUAs + 3 conditional approvals |
| USDA response action | Aerial sterile insect releases in TX and NM |
| Human U.S. cases confirmed | 0 (risk to general public assessed as low) |
| Mexico/Central America human cases since 2023 | 2,100+ |
What New World Screwworm Is — and Why It Moves Fast
New World screwworm (Cochliomyia hominivorax) is not a typical wound parasite. It feeds exclusively on living tissue — not dead or necrotic material. When a female fly detects a wound or body opening, she deposits 200 to 300 eggs in or near it. As the CDC describes, the eggs hatch within hours, and the maggots burrow into living flesh — creating expanding, destructive wounds known as myiasis. Without treatment, severe infestations can be fatal in both animals and humans.
The disease moves with the insects. NWS cannot spread from animal to animal, animal to human, or person to person — the only way infestation occurs is through direct contact with the fly's eggs in a fresh wound or body opening. This means proximity to an infested animal does not itself constitute exposure; the fly must be present and must locate a wound.
According to CIDRAP, the American Veterinary Medical Association has created a dedicated website to help veterinarians recognize and treat NWS infestations in pets, and the AVMA advises clinicians to report any potential cases to state or federal animal health officials.
Who Is at Risk — and What Pet Owners Must Watch For
Pet owners in southern Texas and neighboring regions face the most immediate practical risk. Any outdoor-dwelling pet with open wounds — from injuries, surgery, insect bites, or even minor skin abrasions — is potentially susceptible if NWS flies are present. Equus Magazine's coverage of the FDA authorization notes the risk for pets is "generally low but has increased for those recently in areas with confirmed cases."
Warning signs of NWS infestation in pets include:
- Expanding or worsening wounds despite apparent cleaning
- Visible larvae (maggots) in or around a wound
- Strong, unpleasant odor from the wound site
- The animal persistently biting, scratching, or agitating a wound site
- Unexplained lethargy or distress alongside a wound
- Wounds in or near body openings (eyes, ears, nose, genitals, navel in young animals)
Pet owners in Texas and New Mexico who observe any of these signs should contact a veterinarian immediately, use generic nitenpyram OTC as directed if the product is available, and report the suspected case to their state or local animal health officials. For NWS diagnostic assistance, veterinarians can contact USDA APHIS or their state veterinarian's office. Human cases should be reported to state or local health departments, and clinicians can reach the CDC at dpdx@cdc.gov.
The Containment Strategy — Sterile Insect Releases and Why They Work
The USDA's primary biological containment strategy is the sterile insect technique (SIT) — releasing male screwworm flies that have been sterilized by radiation into the wild. Sterile males compete with wild males for mating with wild females, but sterile matings produce no offspring. As the proportion of sterile males in the environment increases, the wild population declines and eventually collapses.
The U.S. successfully used SIT to eradicate NWS from the domestic U.S. in the 1960s–1970s and maintains a suppression zone in Panama to prevent re-entry from South America. The current outbreak — which originated in Central America's 2023 resurgence — has bypassed that buffer zone, prompting the aerial sterile insect releases now underway in Texas and New Mexico as the first-response containment action.
Frequently Asked Questions
What is the FDA-authorized treatment for New World screwworm in pets?
The FDA issued an Emergency Use Authorization on June 11, 2026, for generic Nitenpyram Tablets — available over the counter in two sizes (11.4 mg and 57 mg), dosed by the animal's weight. It kills most larvae within hours. A second dose must be given 6 hours after the first. It is approved for dogs, puppies, cats, and kittens weighing at least 2 pounds and at least 4 weeks old.
Does nitenpyram prevent future screwworm infestations?
No. Nitenpyram is short-acting and treats active infestation only. It does not provide lasting protection. Because it kills larvae but does not remove them, a veterinarian may still need to manually extract remaining larvae after treatment.
Are humans at risk from New World screwworm?
The CDC assesses the current risk to the general U.S. public as low. No U.S. human cases have been confirmed. NWS cannot spread from animals to people through proximity — a fly must directly deposit eggs in an open wound or body opening. However, 2,100+ human cases have been documented in Mexico and Central America since 2023.
How does New World screwworm spread?
NWS is spread by the fly, not by animal-to-animal or animal-to-human contact. A female fly lays 200–300 eggs in open wounds or body openings of warm-blooded animals. The eggs hatch within hours into maggots that burrow into living tissue. The key prevention is protecting any open wound from fly exposure.
What is the USDA doing to contain the outbreak?
The USDA is conducting aerial releases of sterile male screwworm flies in Texas and New Mexico. Sterile males mate with wild females but produce no offspring, reducing the wild population over time. This sterile insect technique successfully eradicated NWS from the U.S. in the 1960s–1970s.
