Key Takeaways
- If you live in or near Edwards, Gillespie, La Salle, or Zavala counties in Texas, or Lea County in New Mexico, inspect your pets daily for wounds, behavioral changes, or unusual odors. These are the confirmed case areas as of June 23.
- The FDA-authorized nitenpyram tablets are over-the-counter and kill most larvae within hours, but they do not prevent future infestation and a vet may still need to physically remove remaining larvae. The OTC pill is a first step, not a complete treatment.
- Pet insurance covers the vet visit for larval removal, wound debridement, and hospitalization under most accident-and-illness plans. The OTC tablets alone, if they fall below your deductible, may not generate a reimbursable claim. Complex screwworm cases can exceed $5,000 in vet costs.
- Enrolling in pet insurance today will not protect against an infestation your pet already has. Waiting periods of 14 days for illness mean any condition present at or near enrollment will be treated as pre-existing.
The New World screwworm, a flesh-eating fly parasite that the United States eradicated in 1966, has confirmed domestic cases in five counties across Texas and New Mexico. Sixteen animals have been affected as of June 23, 2026, according to the USDA APHIS case dashboard last updated that day. On June 11, the FDA issued Emergency Use Authorization EUA 006661 for generic Nitenpyram Tablets, the first generic animal drug authorized to treat screwworm myiasis in dogs and cats.
This is not a theoretical threat for pet owners in south and west Texas. It is active and spreading.
What the FDA authorized and what it does
Nitenpyram tablets are available over the counter in two sizes: 11.4 mg and 57 mg, dosed by pet weight. They work fast. The drug kills most New World screwworm larvae within hours of the first dose. A second dose is required six hours after the first.
There are limits. The tablets cannot be used in pets under 2 pounds or under 4 weeks old. More significantly, the drug is short-acting. It treats an active infestation but does not prevent future ones. And because the tablets kill larvae without physically removing them, a veterinarian may still need to manually extract remaining larvae from wounds. The OTC pill is a starting point, not a complete treatment protocol.
Acting FDA Commissioner Kyle Diamantas noted that the agency ‘has spent nearly a year fast-tracking reviews and readying for the arrival of New World screwworm in the US.’ The EUA is the tenth the FDA has issued for drugs targeting NWS across multiple species, alongside three conditional approvals. Elanco’s Credelio Quattro-CA1 holds a conditional approval; Credelio also holds a separate EUA.
The CDC activated an emergency operations center on June 11, the same day as the EUA, supporting USDA and Texas health officials. Florida Agriculture Commissioner Wilton Simpson expanded state emergency restrictions, prohibiting rescue dogs and cats from states with confirmed NWS detections from entering Florida.
Where the cases are and what the risk looks like
Confirmed domestic animal cases are in four Texas counties: Edwards, Gillespie, La Salle, and Zavala. Lea County in New Mexico also has confirmed cases. The outbreak is concentrated in a corridor of south-central and southwest Texas, consistent with the geographic pathway of spread from Mexico, where more than 185,000 animal cases and 2,175 human cases have been reported.
The FDA classifies most U.S. dogs and cats as low risk. That assessment changes for pets with open wounds, recent surgery, or skin conditions who live in or near the confirmed-case counties. Cochliomyia hominivorax, the fly behind the outbreak, lays eggs in open wounds or body openings. The larvae burrow into living tissue. Untreated infestations are fatal.
What pet insurance actually covers here
Pet insurance policies are written to cover illness treatment, but ‘illness’ in the policy language almost always carries a waiting period, typically 14 days. What this means operationally: if you enroll a pet today because you live in Edwards County, Texas, and your dog already has a wound that looks suspicious, that condition is almost certainly going to be flagged as pre-existing. The insurer’s claims team will look at the enrollment date, look at the treatment date, and deny the specific claim if the math doesn’t clear the waiting period. I’ve reviewed enough of these policies to know the waiting-period clause is the single most common reason screwworm-type claims would get partially or fully denied, not a coverage exclusion for parasites. Most accident-and-illness plans do cover parasite infestations. The clock is the problem.
For pet owners already enrolled in a comprehensive accident-and-illness plan, the coverage picture is better. Vet costs for screwworm treatment can include wound debridement, anesthesia, IV fluids, and hospitalization. Emergency vet visits average over $1,500. Complex cases can run $5,000 to $10,000 or more, particularly if larvae have penetrated deeply or a pet goes undiagnosed for several days. Those vet-administered treatment costs fall within what most A&I plans cover, subject to your deductible and reimbursement rate.
The OTC nitenpyram tablets themselves are a different question. If a pet owner buys the tablets and treats at home without a vet visit, that cost is small and will almost certainly fall below most deductibles. That is not a coverage failure. That is the drug working as intended, quickly and cheaply. The vet visit for follow-up removal and wound care is where insurance becomes relevant.
Pet services costs are rising. The Bureau of Labor Statistics reported a 5.1% increase in the pet services CPI over the 12 months ending February 2026. Emergency vet costs in particular have outpaced that figure in affected regions. If you are in a confirmed-case county and do not have coverage, look at pet insurance cost now, not after you find larvae in a wound. The 14-day waiting period is the barrier.
What to do if you’re in an affected area
Inspect your pets daily. Look for wounds that seem more painful than expected, unusual odors from any wound or body opening, or visible larvae. Any of these signs require a vet visit, not home treatment alone. The NWS larvae burrow quickly and an infestation that looks minor on day one can be severe by day three.
If your vet confirms an infestation, nitenpyram tablets are now available without a prescription. Use them. Then let your vet complete the treatment.
For pet owners evaluating coverage options, our guide to the best pet insurance breaks down which plans cover parasite-related illness treatment and how the waiting period structures compare. The outbreak is small and geographically contained for now. USDA’s sterile fly release program is the primary containment strategy, and it has worked before. But 16 confirmed domestic cases in three weeks is a real number, and the fly’s range can expand.
