BIG PINE KEY, Fla. — No evidence of screwworm has been found in hundreds of pets examined for signs of the parasite killing endangered deer in the Florida Keys, according to state and federal agriculture officials.

Veterinarians checked about 75 cats and dogs Sunday at a veterinary hospital in Marathon, Monroe County spokeswoman Cammy Clark said in an emailed statement.

Any animal being driven north from the Keys onto the mainland also must stop for a screening at a Key Largo checkpoint. Over 520 dogs, 20 cats, two parrots and one rabbit had been cleared at the checkpoint by Friday, according to Florida’s Department of Agriculture and Consumer Services.

New World screwworms are maggots that feed on living, warm-blooded animals. Infected pets usually survive with treatment, but dozens of endangered Key deer on a federal wildlife refuge have died since the summer because of screwworm.

According to The Citizen ( ), Big Pine Key resident Lance Gates begged employees from the National Key Deer Refuge at a public meeting Saturday to help one of the dog-sized deer that was lying underneath his home.

“The flies were driving him crazy,” said Gates, adding that he sprayed the deer with insect repellent. “He looks OK and I think he can be saved. It’s a real shame.”

Monroe County Commissioner George Neugent, who represents Big Pine and No Name keys, hosted the meeting for residents who regularly see Key deer from the refuge run through their yards like pets.

“They are iconic,” Neugent said. “We have dealt with hurricanes, but never anything like this.”

Refuge manager Dan Clark said 79 Key deer had been euthanized by Thursday, including 47 since officials confirmed the screwworm infestation Sept. 30. Only about 1,000 Key deer remain in the islands.

The parasite once cost the livestock industry millions every year, but there hadn’t been a U.S. infestation in over 30 years.

To suppress the screwworm fly population, officials plan to release over 1.9 million sterilized flies every week. The flies being released are males sterilized with radiation, and no offspring are produced when they mate with wild female flies.

The sterilized fly releases would be expanded Tuesday “as an extra precaution” over three islands south of the refuge, according to a statement from Florida’s Department of Agriculture and Consumer Services.

It may take six months to contain the infestation. Sterile flies are widely used in agriculture, but they’ve never been used to protect wildlife, Heather Stockdale Walden, a University of Florida parasitologist who identified the larvae sent from refuge biologists, told The Miami Herald ( ).

The U.S. Department of Agriculture is using genetic material from flies on Big Pine Key to compare to flies collected around the world in to try and determine the infestation’s source, said Jennifer Meale, spokeswoman for the state’s agriculture department.