A confirmed case in Lea County has prompted enhanced surveillance as officials work to prevent the pest from spreading into livestock and wildlife Populations
CIBOLA COUNTY, N.M. – A parasitic fly that most New Mexicans have never seen is suddenly back in the news.
On June 3, the U.S. Department of Agriculture (USDA) confirmed that a New World screwworm infestation had been detected in a three week old calf in Zavala County, Texas. The larvae of this fly burrow into the flesh of living animals, causing devastating wounds and potentially death. Although humans can be affected in rare cases, livestock and wildlife are particularly at risk, and animal health officials warn that early detection and rapid reporting are essential to stopping its spread.
First Case Reaches New Mexico
Over the weekend, USDA reclassified one of its newly reported cases to Lea County, New Mexico after discovering that a dog treated in Andrews County, Texas actually lives in the town of Eunice. This marks the first confirmed screwworm case in the state.
Dr. Samantha Holeck, the state veterinarian, said during a Monday briefing that a team is on the ground in Eunice, no additional cases have been found and enhanced surveillance is ongoing. She emphasized that the infestation is not contagious: “The fly lays eggs on open wounds and mucous membranes and is not transmitted from one animal to another or from animals to people.” The case also does not pose a food safety risk, she said, because New Mexico’s meat inspection program is robust.
Secretary of Agriculture Jeff Witte said the New Mexico Livestock Board learned about the dog on Sunday morning and immediately dispatched inspectors and NMSU Cooperative Extension Service personnel.
Officials are still investigating how a homebound dog contracted the pest.
Witte stressed that early detection is the key to controlling screwworm: “The sooner we can determine the presence of screwworm, the faster we can stop it.”
In addition to the Eunice dog, the USDA on Monday confirmed a goat in Gillespie County, Texas as well as a calf in La Salle County, Texas and a dog in Andrews County, Texas. As of press time, a total of five U.S. cases have been confirmed in less than a week, according to the American Veterinary Medical Association (AVMA).
State’s Response and Guidance
New Mexico’s Department of Agriculture and Department of Health had already issued a joint statement last week noting that no screwworms had been found in the state and urging travelers returning from south Texas to check their animals.
“While New World screwworm has not been detected in New Mexico, USDA’s confirmation of the pest in South Texas serves as an important reminder for everyone to remain vigilant,” Witte said. The agencies encouraged anyone traveling with livestock, horses, pets or other animals to the affected area to monitor them closely and report any suspicious wounds or infestations.
State officials are treating the Eunice detection as an isolated incident but have ramped up surveillance in the area. They are working with the New Mexico Department of Wildlife to monitor wildlife; screwworm larvae can also infect wild mammals and birds.
Residents who recently visited south Texas or northern Mexico should inspect animals daily.
The USDA urges owners to look for draining or enlarging wounds, maggots or egg masses, signs of discomfort or irritability, and lesions around body openings such as ears, nose and umbilicus.
Anyone suspecting an infestation should contact a veterinarian, NMSU county extension agent or state animal health official immediately.
How Officials are Responding
After the initial detection in Texas, the USDA and the Texas Animal Health Commission formed a unified incident command team and established a 20 km quarantine zone around the infected ranch. Response measures include movement controls, increased trapping for screwworm flies and management strategies for wildlife.
Officials have deployed ground release chambers and ramped up aerial releases to more than four million sterile screwworm flies per week. The sterile fly technique, pioneered in the 1950s, involves releasing radiation sterilized male flies so that wild female flies produce no viable offspring. This strategy successfully eradicated screwworm from the United States in 1966 and is being redeployed to contain the current outbreak.
Dr. Holeck said that if surveillance detects more local cases, New Mexico will work with the USDA to implement similar measures, including ground release chambers in the area where the dog originated.
If a breeding population is found, officials would establish an “infested zone,” impose movement restrictions and expand inspections to all warm blooded animals. She also noted that several FDA approved products can treat screwworm; her office can request additional supplies through the USDA’s National Veterinary Stockpile.
USDA officials say more than 75 personnel are working on the ground in Texas, supported by laboratory diagnosticians, logistics teams and pilots.
Implications for Ranchers and the Beef Supply
Cattle ranchers have expressed concern that the outbreak could lead to higher beef prices if it spreads.
Secretary Witte said there is no expectation that screwworm will disrupt the beef supply because officials have responded quickly and expect mortality to remain low. The AVMA notes that screwworm larvae eat the living tissue of mammals and birds and can cause severe damage or death if not treated, but state officials emphasize that early detection makes infestations treatable. Dr. Holeck said there are multiple approved products to fight the pest – some available through the FDA and others through the international veterinary stockpile – and that the state will help veterinarians obtain them.
One economic impact is already being felt: Mexico halted imports of most U.S. animals, including pet dogs, after the initial Texas cases, and Canada and several U.S. states have imposed their own restrictions. Witte said he is working with federal partners to ensure that any trade restrictions remain localized and to mitigate potential losses for New Mexican producers.
Staying Informed and Vigilant
State officials continue to stress vigilance, not panic.
New Mexicans are encouraged to learn the signs of screwworm and review preparedness resources. The state has created ScrewwormNM. org for reporting guidance and updates, and the USDA maintains a national reporting page at screwworm.gov.
Animal owners should inspect pets and livestock regularly – especially if animals have recently traveled to south Texas or across the border – and report anything suspicious. As Secretary Witte said, “Early detection and reporting are essential”.
With coordinated efforts from state and federal agencies and cooperation from animal owners, officials say there is a good chance to keep the screwworm from gaining a foothold in the Land of Enchantment.