Senior Farm and Ranch Broadcaster Ron Hays features comments with Dr. Burke Healey, USDA’s APHIS Executive Director for VS’ Strategy and Policy division, about the New World Screwworm (NWS) situation in Southern Mexico. The parasitic fly is known for infesting open wounds on livestock, especially cattle, and poses a significant threat to other mammals, including humans, and occasionally, birds.
For context, the NWS had been eradicated from the continental United States (US) since the 1970s with partnerships between the US and Mexico pushing the pest to Mexico’s southern border by 1986; however, due to the pest’s ability to be unknowingly transported, there have been isolated incidents of NWS in the US such as the 2016 identification in the Florida Keys in Key deer, pets, and swine.
Last November, reports confirmed that the pest had resurfaced in the southern Mexican state of Chiapas, and the U.S.-Mexico border was closed to animals moving North out of Mexico. In March, the border was reopened with stringent protocols to prevent potentially affected cattle from being moved.
As the NWS continues a very slow northward trek, efforts are being made to fund and add more fly breeding facilities, which produce sterile male flies to release into existing screwworm populations in order to breed them into extinction – the most effective way of dealing with them thus far.
Dr. Healey isn’t impressed with the progress so far. He explained that since screwworms invaded Southern Mexico last fall, cases there have been increasing by 20% to 27% per week and are now up to more than 700 cases.
“We have transferred all of the sterile flies from Panama to Mexico to try to mitigate that and hold them in Mexico,” he explained. “Right now, we are at the Isthmus of Tehuantepec and are trying to maintain that as a barrier in collaboration with the Mexican authorities down there.” (Editor’s note- see the map below which shows the narrow neck of land in Mexico between the Pacific Ocean to the south and the Gulf of Mexico to the north)
Currently, the only fly breeding facility in operation is in Panama and is at its limit. “As we pushed the flies South, we closed the plants in the U.S., Mexico, and Nicaragua, and left the plant in Panama to hold the barrier, but today it is the only facility we have.”
The facility has been beefed up to produce 100 million flies per week, which should be effective for holding the barrier at the Isthmus of Tehuantepec, but if the flies make it through that barrier, the land mass grows exponentially, and more sterile flies will be needed. The next barrier to focus on will be the U.S.-Mexico border.
“We are exploring options to see how we can expand that production, either in the U.S. as one potential option and in Mexico as a second option,” Dr. Healey said.
Transporting the flies into the Florida Keys during the 2017 outbreak was manageable, but moving them up to 1700 miles to reach Texas or further north into Mexico exceeds the capacity to release flies that still have some virility and stability to do their jobs.
According to Dr. Healey, the chances of the flies making it through the barrier at the Isthmus of Tehuantepec, through Northern Mexico, and into the U.S. are considerable.
“That is what concerns us,” he said. “The challenge is that the flies move the quickest on animals. That is how they moved from Panama into Mexico as quickly as they did was through illegal cattle movements. The same thing could happen to us.”
Although Mexico operates various checkpoints, flies have already broken through some and have reached the secondary boundary established for them. Cattle are constantly moving from Southern Mexico into Northern Mexico, and the U.S. imports Mexican cattle regularly. There is a rigorous process at the border involving three checks: an initial inspection by a Mexican-accredited veterinarian, a secondary inspection by a Mexican Federal government official, and a final inspection by a USDA official.
“We are confident about the animals we are bringing in on an import, but nonetheless, if the flies are on the native cattle at the border, then they don’t know the boundary. They’ll move into the U.S. just as well as they will into Mexico,” Dr. Healey concluded.
The Beef Buzz is a regular feature heard on radio stations around the region on the Radio Oklahoma Ag Network and is a regular audio feature found on this website as well. Click on the LISTEN BAR at the top of the story for today’s show, and check out our archives for older Beef Buzz shows covering the gamut of the beef cattle industry today.
