USDA Announces Eradication of New World Screwworm in Florida

Dan Florida, Industry News Release

Screwworm Larvae

Screwworm Larvae

USDA’s Animal and Plant Health Inspection Service (APHIS) is announcing the successful eradication of the New World screwworm (NWS) from Florida.

“I want to personally thank our many collaborating partners at the Federal, State, and local levels,” said Dr. Jack Shere, USDA Chief Veterinarian.  “Through their dedication and professionalism close to 154 million sterile flies have been released, 16,902 animals have been inspected at checkpoints, and almost 430 hours of active surveillance in the Keys and 250 hours of active surveillance on the mainland have been completed.  Their tireless work has allowed us to eliminate New World screwworm from the United States once again.”

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Dr. Jack Shere, USDA Chief Veterinarian, says experts are still trying to pin down the source of last fall’s screwworm infestation in the Florida Keys.

Animal health checkpoints, or interdiction stations, were closed on Saturday. The last sterile fly releases in Homestead, FL took place on Tuesday and fly releases are scheduled to end on April 25 in the Florida Keys.

New World Screwworm (Cochliomyia hominivorax)

New World Screwworm (Cochliomyia hominivorax)

APHIS considers an area to be screwworm-free through surveillance which includes trapping flies and visually inspecting animals for signs and symptoms of NWS infestation. No new cases of NWS have been reported in Florida since January 10.  Science shows that, when sterile flies are released, elimination of NWS is achieved three life cycles after the last detection. The flies have on average, a 21-day life cycle, and they continue to circulate in the area for three weeks beyond each release. In the Keys, APHIS will complete five life cycles beyond the last positive screwworm detection. Out of an abundance of caution, APHIS also released flies in the Homestead area for three completed life cycles.

APHIS and Florida Department of Agriculture and Consumer Services (FDACS) will continue passive surveillance to ensure any new findings are quickly identified. This surveillance includes veterinarians reporting any suspicious cases, wildlife surveillance, concerned citizens that see suspicious wounds on animals or even on a person, and continued communication with the parks and the National Key Deer Refuge.

APHIS began releasing sterile flies in October 2016, as part of aggressive eradication effort undertaken in collaboration with the U.S. Fish and Wildlife Service, FDACS, and local partners.  More information about the screwworm response can be found here: