A Flesh-Eating Parasite Is Killing Deer in the Florida Keys
The deadly New World screwworm, long ago presumed eradicated, has re-emerged to threaten livestock, deer and other warm-blooded animals in the state.
A lethal, flesh-eating parasite thought eradicated in the United States in 1982 has suddenly re-emerged in Florida to threaten livestock, deer, and other warm-blooded animals.
According to the U.S. Department of Agriculture (USDA) and the Florida Department of Agriculture and Consumer Services, the New World screwworm (Cochliomyia hominivorax) has made its first appearance in Florida in decades, sparking an agricultural state of emergency.
Thus far, more than 100 Key deer – a species already endangered – have died at the hands of the worms, which are fly larvae (maggots) that gain entry to an animal's insides through open wounds and then feed on the creature's flesh. While flies on their own can promote the worm's spread, officials say it's more likely that the pest will travel long distances when carried to new places by infested animals.
The parasite's resurgence was first announced by Florida wildlife agencies in early October, when the worm was found in Key deer in Big Pine Key. Just two weeks later came word that it was found in deer in six other locations.
When the screwworm larvae feed on an infested animal, the creature's wounds grow larger. Livestock may eat less and grow increasingly uncomfortable. If they don't receive treatment, infested animals may die within one to two weeks.
"The screwworm is a potentially devastating animal disease that sends shivers down every rancher's spine," said Florida's agriculture commissioner, Adam H. Putnam, in a statement. "It's been more than five decades since the screwworm last infested Florida, and I've grown up hearing the horror stories from the last occurrence."
The USDA began attacking the parasite in 1957 by releasing sterile male flies in areas of screwworm infestation, starting in the southeast and then moving to other parts of the country – over time, effectively breeding the fly out of existence. The tactic worked, and by 1966 the worm was considered wiped out in the United States. A follow-on program with Mexico ensured animals from that country could not bring the parasite across the border, and by 1982 the United States was thought to be free of the screwworm.
Now, history is repeating itself. The USDA and local Florida wildlife officials, per an agricultural emergency declaration, are trapping flies to figure out how widespread the infestation might be and are releasing infertile flies to stamp out further breeding of the pest. Meanwhile, animal inspection checkpoints have been established to help protect northern Florida from infestation.
While the screwworm will infest human wounds, such cases are considered very uncommon. People with the worm experience discomfort and itchiness at the wound site.
Thus far, there have been no reported cases of humans or livestock becoming infested. Wounds that do become infested with the screwworm can be treated with cleaning and a topical pesticide.
"This foreign animal disease poses a grave threat to wildlife, livestock and domestic pets in Florida," Putnam said. "Though rare, it can even infect humans. We've eradicated this from Florida before, and we'll do it again."
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