Oklahoma Farm Report’s Ron Hays talked with Executive Vice President Michael Kelsey of the Oklahoma Cattlemen’s Association about the encroachment of the New World Screwworm into southern Mexico as it has marched from Panama in recent months across Central America.
On November 22, 2024, the Chief Veterinary Officer of Mexico notified the United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) of a positive detection of New World screwworm (NWS) in Mexico. The NWS was found in a cow in the southern Mexico state of Chiapas, at an inspection checkpoint close to the border with Guatemala. NWS are fly larvae that infest the living tissue of warm-blooded animals, causing infection.
“There is really nothing ‘New World’ about this,” Kelsey said. “It is the same pest that the cattle industry became very familiar with back in the ‘30s, ‘40s, and ‘50s. Then we eradicated them in the mid-’60s.”
It cost about $750 million to eradicate the flies in the ‘60s, so that number would translate to a much higher cost in today’s economy if they were to make a comeback.
Mexico eradicated them in the ’90s, and other southern countries had pushed the population all the way to the Darién Gap of the Panama Canal, then continued to fund the release of sterile male flies into the population to breed them into extinction.
“Mexico lost one of their fly facilities, so there is only one sterile fly facility in Panama that has been producing flies for some time now,” Kelsey said. “We have been working in concert with NCBA for several months, and saw it come around some of those Central American countries.”
Panama reported 23 cases in 2022, but several thousand in 2023. In the last two years, screwworms have spread north throughout Panama and into Costa Rica, Nicaragua, Honduras, Guatemala, and now Mexico. This increase is due to multiple factors including new areas of farming in previous barrier regions for fly control and increased cattle movements into the region.
APHIS initiated a stop-movement order on all bovine preventing them from being brought into the United States. “We understand from USDA that they are working on some protocols to allow cattle trade to resume, but it will be very specific in terms of quarantines on the southern side of the border to make sure those cattle are clean before they are brought in,” Kelsey explained.
According to Kelsey, the fly’s life cycle is pretty basic, so the quarantine should be pretty straightforward and effective. “We have a lot of treatments that we didn’t have back in the fifties and sixties that will allow us to manage them much more effectively, but we just don’t want to get to that point at all.”
Ivermectin is one of the most effective treatments today.
OCA has been in communication with their congressional delegation for information but is also pushing for USDA to strengthen its protocols to assist Mexico.
“Every dollar we send to Mexico to assist in fly strategies is a very efficient use of funding because if the fly gets to this country, we are going to have to spend way more,” Kelsey said. “The efficient use of funds at this time is to help Mexico re-establish that bio-border and push that fly back into the Central America area.”
He emphasized the importance of remaining aware of signs of the fly and persistent in its eradication. He talked in more depth about how the flies were dealt with in the first infestation, so be sure to click the listen bar at the top of the page to hear the complete conversation.
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