A horse in Grant County has been infested by a parasitic New World screwworm fly, the New Mexico Department of Agriculture announced Thursday.
It’s the state’s second case since the sometimes-deadly fly made its return to the United States this summer, after being largely eradicated from the country decades earlier. A dog in Lea County recovered from a June infestation.
However, this case comes as state and federal officials make preparations to reopen the Santa Teresa port — the border crossing in southern Doña Ana County that handles a significant chunk of all American cattle imports — to livestock imports, after the threat of screwworm infestations kept it closed for more than a year. Imports are scheduled to restart later this month.
The case in Grant County is not expected to delay the reopening of the Santa Teresa port, said Dr. Samantha Holeck, state veterinarian with the New Mexico Livestock Board. She added, state livestock officials are still investigating how the horse became infested by New World screwworm, given that it hasn’t recently moved from the remote mountainous region.
“At this point, [there are] still really a lot of unknowns, but we are working to collect as much information as we can, as fast as we can,” Holeck said.
About screwworm
Common in the Caribbean and Central America, the New World screwworm fly poses a major threat to the livestock industry. The flies’ larvae burrow into the flesh of warm-blooded creatures such as livestock, pets, wildlife and, in rare cases, people, causing painful and putrid wounds.
Federal agriculture officials have confirmed 50 screwworm infestations since the fly returned to the U.S. in June. That includes New Mexico’s new case in Grant County as well as two active cases — in a horse and a dog — in southwestern Texas.
Across the border, however, cases are much higher. The federal agriculture agency has identified dozens of cases in Mexican border states of Sonora, Chihuahua, Coahuila, Nuevo Leon and Tamaulipas.
Health and agricultural officials have been monitoring the screwworm long before the U.S. saw its first infestation this year.
The U.S. Department of Agriculture has greatly increased efforts to breed and disperse sterile screwworm flies, which can’t produce the larvae that would otherwise pose a threat to livestock. The agency in recent months has announced the completion of a sterile fly dispersal facility and the groundbreaking of a sterile fly production facility, both near the southern tip of Texas.
Another sterile fly dispersal facility is planned in Arizona, U.S. Agriculture Secretary Brooke Rollins said in July.
Meanwhile, the U.S. Food and Drug Administration has issued emergency use authorizations for medications to prevent and treat screwworm infestations.
Several state agencies — including the departments of agriculture, health and wildlife and the state livestock board — have also worked with the U.S. Department of Agriculture and U.S. Fish and Wildlife Service to monitor for the presence of the screwworm.
That level of government response — particularly from federal officials — was welcome, said Tom Paterson, president of the New Mexico Cattle Growers’ Association.
“We’ve gone through decades where the people in Washington didn’t pay attention, and this has been different. … They have absolutely paid attention. They have moved heaven and Earth to make sure that we can protect the American cattle herd,” Paterson said.
Reopening Santa Teresa
Authorities are taking steps to keep protecting the American cattle herd, even as cattle imports are set to resume in Santa Teresa.
The U.S. Department of Agriculture has been planning since July to reopen ports along the southern border to livestock imports in phases.
The move comes as federal officials both encourage beef consumption and attempt to reduce beef costs for consumers. In August, President Donald Trump signed a proclamation allowing import of 300,000 tons of beef over 90 days without triggering an “out of quota” tariff, angering ranchers.
The federal government restarted cattle imports in Douglas, Ariz., in late August. After Santa Teresa, the port in Columbus, N.M. — in Luna County, south of Deming — is next in line.
Santa Teresa is a big player when it comes to livestock imports. Each year, hundreds of thousands of cattle cross the border at Santa Teresa, most of them destined for pastures and feedlots across the West and Midwest before eventually being processed for beef, according to the New Mexico Border Authority.
To ensure they’re screwworm-free, all imported cattle will be inspected at least four times during the import process, with inspections occurring on both sides of the U.S.-Mexico border, Holeck said.
“It’s a pretty good process, really — a lot of eyes on those cattle, very low risk for those animals to bring screwworm into the country,” she said.
That response — combined with expanded sterile fly dispersal efforts and a larger array of drugs available to treat screwworm — is reassuring for New Mexico ranchers, Paterson said. It makes it very unlikely the parasitic pest will hitch a ride into New Mexico on imported cattle, he said.
But, he noted, precautions at Santa Teresa won’t stop the screwworm from entering the state in other ways — such as after infecting wildlife or by flying.
“It means that we have to remain vigilant about monitoring our herds and paying attention to it — not to panic, but to remain diligent,” Paterson said.
Margaret O’Hara reports on issues affecting healthy communities in New Mexico. Her work is funded by a grant from Anchorum Health Foundation. Anchorum will not have any role in editorial decisions. The New Mexican and its Public Service Journalism Fund retain full editorial control. Philanthropically funded stories by The New Mexican are made available to all readers without a paywall.
