Federal and state officials are watching for further signs of New World screwworm, a maggot that kills animals by feeding on their flesh, after the pest was found in wounds on a stray dog near Homestead, in Miami-Dade County in southern Florida. “This is the first confirmed case on Florida’s mainland,” said USDA’s Animal and Plant Health Inspection Service.
The discovery follows the confirmation last Oct. 3 of screwworm in Key deer in a federal refuge on Big Pine Key. It was the first detection of screwworm in the United States in more than 30 years. Since then, infestations have been found on Key deer on 13 of the Keys off of the Florida peninsula. The campaign to eradicate the screwworm has included release of 80 million sterile flies to disrupt reproduction of the fly.
In an epidemiology report, APHIS says the most likely pathway for the screwworm to reach the Keys was transport of larvae by a human or an animal. The adult flies that spread screwworm usually do not travel more than a couple of miles if suitable hosts — animals with open wounds — are available.
A USDA factsheet on New World screwworm is available here.
Separately, APHIS said it has not determined if a wild mallard in Montana was infected with a highly pathogenic strain of avian influenza. “We are still working to isolate the virus to determine pathogenicity,” said a spokeswoman. The duck was killed and sampled as part of USDA surveillance for bird flu. Highly pathogenic bird flu can kill a flock of domestic fowl within 48 hours. The worst-ever U.S. bird flu epidemic of 2014 and 2015 was a “high path” outbreak. Low pathogenic avian influenza viruses are a natural infection of waterfowl and are not a serious threat, says the FAO.