Flesh-Eating Screwworms Reach a Third US State and Are Attacking Pets

The New World screwworm, a parasitic fly whose larvae feed on living tissue, has now turned up in a third US state, according to the US Department of Agriculture. The agency has identified 74 animal cases nationwide since the flies first appeared in June, and the outbreak is no longer limited to livestock. Dogs, cats and other pets are now among the animals being attacked.

The larvae are the source of the "flesh-eating" nickname. Adult flies lay eggs in open wounds or other moist areas of an animal's body, and the hatched larvae burrow into the surrounding tissue and feed on it. Left untreated, an infestation can cause severe damage and can kill the animal. Pets that spend time outdoors are especially exposed, and a small wound that goes unnoticed can become a serious infestation within a short time.

The spread into a third state suggests the fly's range is still growing, which raises concern for owners and for ranchers whose herds are already at risk. Veterinarians generally advise owners in affected areas to check animals regularly for wounds, unusual irritation, foul odors or movement under the skin, and to contact a vet right away if they find anything suspicious. Attempting to remove larvae at home can leave the wound open and make the problem worse.

The USDA's count reflects confirmed cases, so the true number of affected animals could be higher. Owners and farmers who want the latest guidance on reporting, treatment and movement rules should check the agency's animal health updates directly rather than relying on secondhand reports.