New infestations in four counties prompt expanded surveillance and livestock movement restrictions
CIBOLA COUNTY, N.M. – New Mexico animal health officials have confirmed additional cases of New World screwworm in four southern counties, raising concerns about the spread of the parasitic pest as ranchers and livestock owners prepare for colder weather.
The New Mexico Department of Agriculture reported new cases in Grant, Otero, Hidalgo and Doña Ana counties, involving cattle, a horse and a sheep.
Two cases were confirmed in Grant County, involving a horse and a calf. In Otero County, officials identified an infestation in a beef cow near Piñon, while another calf tested positive near Hachita in Hidalgo County.
Two additional cases were confirmed in Doña Ana County, including a sheep on the New Mexico State University campus in Las Cruces and a cow at an off-campus location.
The latest detections follow New Mexico's first confirmed case in June, when a dog in Lea County tested positive. Federal officials lifted restrictions around that initial detection in August after no additional cases were found in the area.
State and federal officials are now expanding surveillance and fly-trapping operations around affected locations to determine whether the pest has spread further.
Infested zones extending at least 12.4 miles around affected locations have been established. Animals within these zones generally must undergo inspections and, when necessary, treatment before being moved within or outside the designated areas.
New World screwworm flies lay eggs in wounds or openings in living tissue. The larvae feed on living flesh and can cause serious injury or death if left untreated.
“This is a critical time as we move toward cooler weather. Cold daytime temperatures can slow screwworm activity, but the risk is not completely eliminated,” said New Mexico Secretary of Agriculture Jeff Witte.
State Veterinarian Dr. Samantha Holeck emphasized the importance of livestock producers checking animals regularly and promptly reporting suspicious wounds.
Officials advise ranchers and pet owners throughout western New Mexico to watch for wounds that fail to heal, maggots, foul-smelling discharge or unusual irritation around injuries.
Anyone suspecting an infestation should immediately contact the New Mexico Livestock Board and avoid moving the affected animal.
Maps of current infested zones, reporting information and animal movement requirements are available at ScrewwormNM. org.