An invasive flesh-eating parasite which the U.S. thought they have eradicated decades ago has came back to haunt them.

According to Science Alert, the re-emergence of the New World screwworm (Cochliomyia hominivorax), has resulted in an agricultural state of emergency being declared in Monroe County, Florida, as authorities try to contain the outbreak.

In October, the United States Department of Agriculture (USDA) confirmed the presence of the parasite in National Key Deer Refuge in Big Pine Key, Florida. It is the first confirmed case since 50 years ago. Their report added that aside from deers, there are also other pets that might have been infested with the same parasite.

Miami Herald notes that as of today, U.S. Fish and Wildlife Service said 875 infested herd have been recorded. The herd had been estimated at 800 to 1,000, based largely on counts done in Big Pine and No Name keys, where deer are concentrated.

NewWorld screwworms are fly larvae (maggots) that can infest livestock and other warm-blooded animals, including people. It infects livestocks by entering an open wound.

"In the very big picture, this is just the latest example of our failure to adequately protect people, agriculture and the environment from consequences of a shrinking world, an interconnected world," said Adam Putnam, Florida's Commissioner of Agriculture, told New York Post. "Millions of cargo containers and millions of passengers arrive every year, entering and exiting Florida and bringing unwelcome pests and disease with them."

To eradicate the parasite, the government is using the sterile insect technique where they are releasing each week, seven million fly pupae sterilized by radiation. The same technique, which was developed by USDA's Agricultural Research Service was used in 1950s to halt the infestation.

"Females that breed with sterile flies get "tricked" into believing they will reproduce and stop mating. These females die without laying eggs, which breaks the life cycle of the screwworm, leading to eventual population decline and collapse," Healthmap states.