New World Screwworm Detected in U.S.

By Tanner Hood

MONTGOMERY, Ala.- The U.S. Department of Agriculture (USDA) announced the first reported case of New World screwworm (NWS) in the U.S. June 3.

NWS is a live animal health concern and is not a food safety or quality issue. NWS does not infect meat. Active checks including inspection are used to prevent meat from impacted animals entering the food supply.

The deadly, parasitic worm was detected in a 3-week-old calf near La Pryor, Texas. NWS can infest a variety of open wounds on a living host, including castration sites, mucosal cavities, insect bites, ear tags, branding wounds, umbilical sites and vaccination sites.

Alabama Farmers Federation Beef Director Chris Prevatt encouraged farmers to be vigilant when checking livestock.

"Producers should begin implementing stringent fly control protocol," Prevatt said. "Keeping an eye on newborn calves, post-partum cows and recently handled cattle is important to detect signs of infection while also being aware of any open wounds. Monitoring and evaluating cattle standing off from the herd, loss of appetite, foul odors and other abnormal behaviors is important to detect signs of NWS."

NWS is passed through adult screwworm flies which lay larvae in open animal wounds and lead to extensive tissue damage. NWS can be identified by orange eyes, a metallic blue or green body and three dark stripes along the back. Adult screwworm flies are similar in size to common houseflies.

Prevatt said farmers will need to begin working closely with USDA, the Alabama Department of Agriculture & Industries and veterinarians to control the issue.

"NWS should not affect our food supply," Prevatt said. "NWS was eradicated in the 1960s, and steps are being taken to prevent further spread. This can only be stopped if farmers, ranchers, hunters, pet owners and others regularly interacting with animals are aware, take preventative measures and report issues."

Questions or concerns should be reported to Alabama State Veterinarian Dr. Tony Frazier at (334) 240-7253. Contact the state veterinarian's office if infestation is suspected.

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