New World Screwworm in Arizona: Signs, Prevention, Treatment, and Pet Travel
Arizona has confirmed New World screwworm in animals. As of November 9, 2026, the Arizona Department of Agriculture reports five cases statewide: two dogs, two horses, and one sheep. The detections occurred in Cochise, Greenlee, and Graham counties, where three active response areas have been established.
No cases have been reported in Peoria or Maricopa County. Still, pet owners throughout Arizona should know how to recognize a suspicious wound and respond quickly. New World screwworm larvae feed on living tissue, so an infestation can become serious without prompt veterinary treatment.
Not every wound or maggot is New World screwworm. However, any animal with maggots in a wound or body opening needs immediate veterinary attention and must be reported to animal-health officials.
What Is New World Screwworm?
New World screwworm is the larval stage of the parasitic fly Cochliomyia hominivorax. Female flies lay eggs along the edges of wounds or near body openings. The eggs hatch into larvae, or maggots, that burrow into living tissue.
Even a small break in the skin can attract the flies. Possible entry points include:
Scratches, cuts, and puncture wounds
Tick or insect bites
Irritated skin and hot spots
Recent surgical incisions
Nail-bed injuries
Moist areas around the eyes, ears, nose, mouth, genitals, or anus
Dogs and cats do not transmit screwworm directly to one another. Infestations begin when a fly lays eggs on an animal. However, an infested wound can attract more flies, making rapid treatment and protection from further exposure important.
Although New World screwworm primarily affects animals, people can also be infested in rare cases. Anyone who finds maggots in a wound should seek prompt medical care.
Signs of New World Screwworm in Dogs and Cats
A screwworm wound may enlarge and deepen as the larvae feed. Pet owners should watch for:
Maggots or pale egg masses in a wound or body opening
A wound that is growing, deepening, draining, bleeding, or failing to heal
Bloody discharge or a foul, decaying odor
Pain, swelling, or persistent licking
Irritability, restlessness, hiding, or unusual sensitivity
Loss of appetite, weakness, or unusual tiredness
Discharge from the eyes, ears, nose, mouth, genital area, or anus
Long hair and skin folds can conceal wounds, so inspect your pet carefully. Pay particular attention to the face, ears, paws, nail beds, abdomen, groin, tail area, skin folds, and recent surgical sites.
Pets that spend significant time outdoors or have allergies, skin disease, parasites, a recent injury, or a healing incision may need especially close monitoring.
What to Do if You Find Maggots in a Pet’s Wound
Do not wait to see whether the larvae disappear. Contact a veterinarian immediately and keep the pet indoors or otherwise protected from flies while arranging care.
Do not pour bleach, gasoline, household insecticide, or other home remedies into the wound. Do not give an antiparasitic medication unless a veterinarian directs you to do so. Products that are safe for one species, age, or weight may be ineffective or dangerous for another animal.
Avoid removing or discarding all the larvae before speaking with a veterinarian or animal-health official. Samples may be needed to identify the species. If possible, prevent the pet from licking or further traumatizing the wound without delaying care.
Suspected cases in Arizona must be reported to the Arizona Department of Agriculture’s Office of the State Veterinarian. Animal owners can report suspicious maggot-infested wounds by calling 602-542-4293 during state business hours or emailing nws@azda.gov.
How Veterinarians Diagnose New World Screwworm
A veterinarian may suspect screwworm based on the wound, odor, discharge, and visible larvae. Appearance alone cannot confirm the species because other types of flies can also deposit larvae in dead or damaged tissue.
For an official diagnosis, veterinary and animal-health teams collect larvae from several locations in the wound, including its deepest areas. Eggs or adult flies may also be collected. State and federal officials coordinate submission of the specimens to an approved laboratory for identification.
Pet owners should not attempt to collect larvae without instructions. Handling a painful wound can cause further injury, and proper sample collection and preservation are important for an accurate diagnosis.
Reporting is part of the response, not merely a paperwork requirement. A confirmed case can lead to surveillance, fly trapping, animal-movement controls, and sterile-fly releases intended to prevent additional spread.
How Screwworm Infestations Are Treated
Treatment generally involves removing visible eggs and larvae, thoroughly cleaning the wound, and using an appropriate antiseptic. Additional care depends on the location and severity of the tissue damage.
A pet may also need:
Removal of damaged or dead tissue
Pain medication
Fluids and supportive care
Treatment for a secondary bacterial infection
An antiparasitic medication appropriate for the species and patient
Repeat examinations to ensure no living larvae remain
The FDA has made conditionally approved and emergency-authorized medication options available for New World screwworm in several animal species, including dogs and cats. Some products may be sold over the counter, but that does not make screwworm suitable for home treatment. The correct medication and dose depend on the pet’s species, age, weight, health history, neurologic risk, other medications, and the severity of the wound.
A veterinarian should examine the wound, direct treatment, and determine when follow-up care is needed.
How Pet Owners Can Reduce the Risk
No single precaution can eliminate exposure, but careful wound management and regular inspections can help pet owners identify problems early.
Check outdoor pets from nose to tail every day.
Examine even small wounds, bites, hot spots, and areas of irritated skin.
Follow veterinary instructions for protecting surgical incisions and other wounds.
Use veterinarian-recommended flea and tick prevention.
Keep pets indoors or reduce outdoor exposure when flies are numerous, especially if the pet has a wound.
Keep pet bedding, yards, and waste areas clean.
Arrange veterinary care for wounds that are painful, draining, foul-smelling, enlarging, or slow to heal.
Check official response-zone information before traveling with an animal.
Do not apply insect repellents intended for people, livestock, or other species unless your veterinarian confirms that the product is safe for your pet.
Traveling With Pets Within Arizona
Arizona’s current animal-movement restrictions are targeted to active Infested Zones rather than applied statewide. Each zone extends 20 kilometers, or approximately 12.4 miles, around a confirmed detection.
Live animals cannot leave an active Infested Zone without authorization through the State Veterinarian’s movement process. Self-inspection is not permitted within an active zone.
Peoria is not currently within an Infested Zone. Nevertheless, response areas can change as new information becomes available. Before traveling, check the Arizona Department of Agriculture’s current New World screwworm map and search your address or destination.
For interstate trips, review the destination state or territory’s current animal-entry requirements. Depending on the destination and outbreak conditions, travelers may need veterinary documentation, vaccination records, testing, treatment, or an entry permit.
Inspect your pet before departure. Delay travel and call a veterinarian if you find a new wound, drainage, an unusual odor, eggs, or larvae.
International Pet Travel and Screwworm Requirements
International pet-travel rules vary by country, species, route, and travel date. Begin with USDA APHIS pet-travel guidance and confirm the destination’s requirements well before departure.
Some documents must be completed within a narrow period immediately before travel. Missing, incorrect, or improperly timed paperwork can result in delays, the animal being held at the border, or denied entry.
Traveling to Mexico With a Dog
Mexico currently requires pet dogs traveling from the United States to have a New World Screwworm Inspection Certificate. A USDA-accredited veterinarian must examine the dog, sign the certificate, and issue it no more than five days before entry.
The dog must have no fresh or healing wounds. The certificate is issued directly by the accredited veterinarian and does not currently require USDA endorsement.
These requirements can change, so verify them again shortly before departure.
Traveling to Mexico With a Cat
Mexico does not currently require a health certificate or screwworm inspection document for a pet cat arriving from the United States. Cats are inspected by Mexican animal-health officials upon arrival and must not have fresh or healing wounds.
Do not add a cat to the dog screwworm inspection form. Doing so can invalidate the document.
Returning to the United States
Dogs entering or returning to the United States from a country or region affected by screwworm must have documentation showing that they were inspected within five days before shipment.
The certificate generally must be signed by a full-time official government veterinarian in the country of departure and state that the dog is free of screwworm. For dogs returning from Mexico, certain trained and authorized clinical veterinarians may issue the required certification on behalf of the government veterinary authority.
If a dog was infested, the documentation must confirm that the animal was quarantined and treated until free of screwworm before travel.
Cats can also become infested even though USDA’s specific screwworm-certification requirement applies to dogs. Any animal suspected of infestation may be denied entry or referred for further evaluation.
Travelers should also check current CDC requirements, including rabies-related rules for dogs. A routine vaccination record or wellness summary is not a substitute for required travel documentation.
Why Sterile Flies Are Part of the Response
New World screwworm was once established across the southern United States. Eradication became possible through the sterile insect technique, in which large numbers of laboratory-raised male flies are sterilized and released into affected areas. When sterile males mate with wild females, the resulting eggs do not hatch.
Repeated releases reduce the reproducing fly population. Combined with animal inspections, wound treatment, surveillance, and movement controls, this approach eliminated established New World screwworm from the United States in the 1960s. It was also used successfully during the 2016–2017 outbreak in the Florida Keys.
Arizona’s current response uses these same core tools. Early detection and prompt reporting remain essential because they allow animal-health teams to act before the fly becomes more widely established.
What Peoria Pet Owners Should Do Now
Peoria pet owners do not need to panic, but they should remain observant:
Inspect outdoor pets and healing wounds every day.
Keep wounds protected from flies as directed by a veterinarian.
Seek prompt care for a painful, draining, enlarging, foul-smelling, or maggot-infested wound.
Check Arizona’s current response-zone map before moving an animal.
Review all destination and return-entry requirements before interstate or international travel.
Report any suspected screwworm infestation immediately.
If your dog or cat has a suspicious wound, call Parkway Animal Clinic at 623-362-8000 for guidance during regular business hours, Monday through Friday from 8:00 a.m. to 6:00 p.m. Text messages are monitored during business hours only.
A pet with rapidly worsening tissue damage, severe pain, weakness, heavy bleeding, breathing difficulty, collapse, or another emergency sign needs immediate emergency veterinary care. Do not rely on routine text messaging during an emergency.
Information current as of November 9, 2026. Case counts, response zones, medication authorizations, and pet-travel requirements can change quickly.
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