Lindsay A. Starkey, DVM, PhD, DACVM-Parasit

In mid- to late-2016, the Florida Keys had a new inhabitant—the New World screwworm (Cochliomyia hominivorax). Technically, this parasite had been present in the United States before, but a strenuous eradication program eliminated the parasite from the U.S. in the mid-1960s.

Screwworm larvae, or “maggots,” feed on the living tissue of a variety of mammals and in late 2016 were confirmed to be infesting mainly Key deer, but also a few domestic animals in the Keys. Active surveillance in the Keys and mainland Florida was initiated following the confirmation of the presence of C. hominivorax. Additionally, the USDA has released sterile flies in and around the outbreak area to re-eradicate this parasite.

On Jan. 9, 2017, the USDA Animal and Plant Health Inspection Service (APHIS) confirmed the presence of New World screwworm on a stray dog near Homestead, Fla. This dog was isolated and treated, and surveillance in the local area was increased. To date this is the only case in mainland Florida following the outbreak in the Keys late last year, and no human infestations have been reported associated with this outbreak.

Florida residents and pet owners should monitor their pets and themselves and report any potential cases to 1-800-HELP-FLA. Visitors have also been advised to check themselves and their pets during and after travel to southern Florida or the Keys and to report suspect cases to (850) 410-3800.


USDA-APHIS factsheet: New World Screwworm. 2014.

Mastrangelo T, Welch JB, 2012. An overview of the components of AW-IPM campaigns against the New World screwworm. Insects 3(4):930-55.