Screwworm, a flesh-eating parasite that can be fatal if untreated, has re-entered the US Southwest for the first time since the 1970s.
Anthony Gallegos, 43, stands in a pasture with some of his cows on his ranch in Zavala County, near La Pryor, Texas, US Jun 6, 2026. (Photo: REUTERS/Kaylee Greenlee)
19 Jun 2026 01:17AM
CHICAGO: Screwworm, a parasitic fly whose flesh-eating larvae feed on living animals, re-entered the US Southwest in June for the first time since the 1970s, posing a threat to the livestock industry as well as wildlife and household pets.This is what veterinarians say pet owners, particularly those near the US-Mexico border, need to know:WHAT ARE SCREWWORMS?Female screwworm flies lay eggs in wounds on any warm-blooded animal. Once the eggs hatch, hundreds of larvae use their sharp mouths to eat through living flesh, eventually killing their host if untreated. They mostly spread through the movement of infested animals, pose no threat to food safety and rarely affect humans, experts said. Animals treated early with maggot removal, wound cleaning and antibiotics generally survive the infestation.A dog in New Mexico was infested with screwworm in June, underscoring the risk to pets in the US Southwest after the pest’s northward spread from endemic regions in Central America and into Mexico.WHAT SYMPTOMS SHOULD PET OWNERS LOOK OUT FOR?
