New Mexico screwworm count hits 30 as pest reaches Catron County

New Mexico recorded 20 new New World screwworm cases between Wednesday and Tuesday, tripling the number of recent infections and bringing the state total to 30 since June. The U.S. Department of Agriculture data shows the parasitic fly is moving into new parts of the state, with the latest finding occurring in Catron County.

The most recent case involved a cow found infested on Saturday. This marks the first confirmed instance of the pest in Catron County. The other 19 new cases were identified in Doña Ana, Grant, Luna, Otero, and Hidalgo counties. The rapid increase has prompted state agriculture officials to adjust how they define the area at risk.

The New Mexico Department of Agriculture expanded the state's infested zone on Tuesday. The previous zone extended at least 12.4 miles around each infected animal's location. The new designation uses a regional model based largely on county lines. As of Tuesday afternoon, the zone covers all of Doña Ana, Grant, Luna, Otero, and Hidalgo counties. It also includes portions of Catron, Sierra, Lincoln, and Chaves counties.

Animals inside this zone must undergo inspections before moving in or out of the area. This requirement applies to livestock, horses, pets, and other warm-blooded animals. Officials implemented the change to clarify movement requirements and support surveillance. Agriculture Secretary Jeff Witte said the goal is to reduce confusion for animal owners. "The new regional zone maps should help people determine whether they are in an area where moving their animals will require an inspection," Witte stated.

New World screwworm larvae burrow into the flesh of hosts, causing painful wounds that can kill an animal in seven to 10 days if untreated. The pest was largely eliminated from the United States decades ago but returned in June. A case in a Lea County dog marked the state's first identification that month. Since then, the U.S. Department of Agriculture has recorded 99 animal infestations across New Mexico, Arizona, and Texas. Recent New Mexico cases have involved cattle, horses, dogs, and a domestic cat in Grant County. Officials also counted a fly found in a trap in Doña Ana County on Thursday.

Livestock officials have asked ranchers, pet owners, and hunters to watch for signs such as wounds that fail to heal, foul-smelling discharge, and unusual discomfort. The New Mexico Department of Health sent an alert to healthcare providers on Oct. 26. The alert asked providers to monitor patients for signs of infestation. While human cases are rare, the alert emphasized the need for early detection and immediate reporting. No domestically acquired human infestations have been identified in the U.S. so far.

State officials continue to monitor the spread of the fly. The expansion of the infested zone changes the logistics for moving animals across the state. Residents in the newly added partial counties must now check their specific locations against the updated maps. The department will update the zone as new cases are reported and confirmed by state and federal agencies.