First screwworm infestation in the US in decades reported in Florida

Federal agriculture officials reported Monday on the first local infestation of New World screwworm in the United States in at least three decades.

According to the United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) the presence of New World screwworm in Key deer from a wildlife refuge in Big Pine Key, Florida was confirmed.

Florida Commissioner of Agriculture Adam H. Putnam declared an agricultural state of emergency in Monroe County.

“The screwworm is a potentially devastating animal disease that sends shivers down every rancher’s spine. 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,” said Commissioner of Agriculture Adam H. Putnam. “This foreign animal disease poses a grave threat to wildlife, livestock and domestic pets in Florida. Though rare, it can even infect humans. We’ve eradicated this from Florida before, and we’ll do it again. We will work with our partners on the federal, state and local level to protect our residents, animals and wildlife by eliminating the screwworm from Florida. The public’s assistance is crucial to the success of this eradication program.”

In addition to the samples from three Key deer that were confirmed positive for screwworm, there are other Key deer from the same refuge and a few pets in the local area that exhibited signs of screwworm over the past two months, though no larvae were collected and tested in those cases. All of the potentially affected animals are from the same area of Big Pine Key and No Name Key. There have been no human or livestock cases.

Animal health and wildlife officials at the state and federal levels are working jointly to address these findings. Response efforts will include fly trapping to determine the extent of the infestation, release of sterile flies to eliminate the screwworm fly population, and disease surveillance to look for additional cases in animals. The initial goal will be to keep the infestation from spreading to new areas while eradicating the New World screwworm flies from the affected Keys.

The Florida Department of Agriculture and Consumer Services has established an Animal Health Check Zone from mile marker 91 south. Animals traveling north will be given health checks at an interdiction station located at mile marker 106 to ensure that they do not have screwworm. This checkpoint will ensure that the screwworm does not travel north and infest other areas of Florida.

In addition to the check zone, the U.S. Department of Agriculture, Florida Department of Agriculture and Consumer Services and other partners are implementing aggressive control and surveillance measures to eradicate the screwworm.

New World screwworms are fly larvae (maggots) that can infest livestock and other warm-blooded animals, including people. They most often enter an animal through an open wound and feed on the animal’s living flesh. While they can fly much farther under ideal conditions, adult flies generally do not travel more than a couple of miles if there are suitable host animals in the area. New World screwworm is more likely to spread long distances when infested animals move to new areas and carry the pest there.

While human cases of New World screwworm are rare, they have occurred, and public health officials are involved in the response.