What Phoenix pet owners should know about New World screwworm

New World screwworm has made a recent comeback , with five confirmed cases in southeast Arizona. Why it matters: Animal owners need to be on the lookout for the deadly parasite even though no cases have been confirmed in the Valley, state officials say. Catch up quick: New World screwworm "is a highly destructive parasitic fly whose larvae feed exclusively on the living tissue of warm-blooded animals," per the Arizona Department of Agriculture. Breakouts in the 1960s and '70s led to its eradication in the U.S., but a recent resurgence in Mexico has reintroduced it here for the first time in decades. Because the screwworm burrows into live tissue, an infestation can cause severe damage and is sometimes fatal. A map of where new world screwworm has been found in Arizona. Red areas are the locations of the three infestation zones, while orange indicates the state's surveillance zone. Photo: Arizona Department of Agriculture. State of play: As of Tuesday afternoon, five cases have been confirmed in the state — two dogs, two horses and one sheep. Those five cases are in three 12-square-mile "infested zones," which no animals can exit without inspection by state authorities. Two of those zones are