After a nearly 50-year absence, flesh-eating screwworms have returned to Florida, making for a dangerous, potentially fatal environment for animals and humans.

According to the USDA, the New World screwworm was detected in Key deer in a wildlife refuge in Big Pine Key, Florida—which has since been declared an agircultural state of emergency. Screwworms are fly larvae (maggots) that feed off of the flesh of living animals. "A major concern for the US is agriculturally important species such as cattle, sheep, goats, horses, and pets such as dogs and cats—and even people," says Michael J. Yabsley of the University of Georgia's College of Veterinary Medicine. "Birds are less commonly infested but can be hosts as well."

The screwworm, which thrives in warmer climates, enters through a wound, break, or cut in the skin of an animal. "Female flies, about the size of houseflies, lay their eggs in and around the wounds or mucous membranes," Yabsley says. "Once the eggs hatch into larvae, they begin to ingest tissues. This is why these screwworms are so devastating—unlike other maggots that feed on dead flesh or animals, these maggots ingest live tissue."

Dr. Douglas Mader, MS, DVM, of Marathon Veterinary Hospital in Marathon, Florida, notes that a screwworm infection in pets and animals is "very painful" and may emit a foul odor and/or ooze fluid. Maggots will be present in the wound and must be removed for the animal to heal properly. If an animal has been infected by screwworms, veterinary care is urgent, as the infection could be life-threatening. Depending on the extent of the wounds, veterinarians will help by eradicating the maggots and giving the animal the proper medication to heal.

"If it’s a minor wound, we can use a local anesthetic, numb the area with novocaine or lanacaine, and then clean the wound out," Mader says. However if the wound is extremely deep, Mader explains that surgery is often necessary to cut away the dead tissue and remove all the maggots."[Pets] are put on medication to kill any maggots that may have been missed," he says.

Still, as scary as screwworms may be, Mader urges pet parents not to panic and to simply take proper precautions. "[Screwworms] are not going to come out of nowhere and attack a healthy animal."

That's why prevention is key. Keep wounded pets and animals indoors and away from flies if possible, says Mader. "If your pet has any wounds, and you have to take it outside, cover the wounds so a fly can’t get to it," he says. If the animal does need to be outside for any period of time, Mader suggests visiting a veterinarian so that proper dressing can be applied to the wound site.

The USDA is currently working to eradicate the screwworms from the Florida Keys.

Find out how to treat minor dog wounds at home: How to Treat Dog Wounds

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