Atlanta, GA |
It’s a pest many of today’s livestock producers have only heard about in stories—but one that once left a devastating mark on the American livestock industry: the New World screwworm. Eradicated from the U.S. more than sixty years ago, this fast-spreading parasitic fly could once again pose a threat, prompting concern among veterinarians and ag officials.
“It really affected our production practices,” says Dr. Jane Marie Hennebelle, Georgia’s State Veterinarian. “We had to shift calving, dehorning, and castration to the cooler months when the fly wasn’t active. The New World screwworm is a maggot that feeds on live tissue. These flies lay eggs on the edge of wounds, and those eggs develop into maggots that burrow into the wound to feed. If we had an incursion today, it could cost livestock producers around a billion dollars a year to respond to and eradicate.”
Although there are currently no confirmed cases in the United States, recent reports from Mexico have put officials on high alert.
“At the end of 2024, USDA notified us of a case of New World screwworm in a cow in southern Mexico,” says Hennebelle. “Since then, Mexico has reported over 1,400 detections. As it moves further north, the risk of detection in the U.S. increases.”
If the pest were to reach Georgia, Hennebelle says the consequences would be immediate and far-reaching—from animal health and productivity losses to regional quarantines and trade impacts.
“It will affect not only animal health, but also your productivity. Animals with screwworm infestations don’t gain weight, don’t want to eat—you’ll see immediate impacts to the health of your herd,” she says. “And if a detection occurs, the area becomes a quarantine zone while we work to eradicate the fly from that region.”
As the summer months approach, early detection becomes critical. Hennebelle is urging producers to be vigilant and report anything unusual.
“Look for any type of wound—it could be as small as a tick bite,” she says. “If you see maggots and are comfortable doing so, use forceps to remove them and place them in rubbing alcohol. Call us immediately. We’ll have them identified at no cost to you.”
She adds that rapid reporting can make all the difference.
“Our experience with high-consequence diseases like avian influenza has shown us that early reporting is absolutely critical,” says Hennebelle. “We need producers to keep eyes on their cattle, livestock, and even farm dogs. If something looks off or you see a wound with a large number of maggots, call us—we will gladly send someone to collect samples and identify them.”
By: John Holcomb