The New World Screwworm hasn't yet made it's way to Arkansas, but cattle farmers and state officials are worried as the pest spreads through a neighboring state.
As of July 14, Texas had 15 active cases of the parasitic fly. The state, which shares a border with Arkansas, reported its first case on June 3.
The New World Screwworm is a parasitic maggot that grows up to become a fly.
The fly looks for open wounds and mucous membranes to lay its eggs.
After hatching, the larvae munch on the host’s flesh. They burrow into the animal like a screw feeding into wood. The majority of cases in the U.S. right now are in livestock, but a number of animals can be infected – like dogs, wild boars and deer. People can also be infected.
Sid Miller, Texas Department of Agriculture commissioner, said wounds affected by screwworm are like something out of a horror movie; they can get gruesome and smell like rotting flesh.
Screwworm was an issue in the U.S. for decades before a coordinated response from the USDA led to its eradication in 1972. In 1960, the U.S. Department of Energy released a documentary called “Roundup.” It described the symptoms of screwworm in cattle.
“Bloody discharge, foul odor, and the larvae embedded full length as their mouthhooks tear into living flesh, are the symptoms of a screwworm infestation,” said the documentary.
Don Hubbell, a cattle rancher and the president of the Arkansas Cattlemen’s Association, said he was around when the parasite was a constant risk for cattle ranchers.
“I was 10 in 1970. But now, I went everywhere with my dad, on the ranch, you know… He’s 90, and I asked him if he ever remembered having a screwworm problem.” Hubbell said. “He remembered one calf that got screwworms and he treated it. And he said he fixed him up, and he lived to sell day. But if he had not treated that animal, he could’ve had more.”
Work to eradicate the pest back then included releasing sterile flies. These are infertile flies treated with radiation.
Since female flies only mate once, if they mate with a sterile male, that stops one line of reproduction. Release enough sterile flies into an environment and you’ve got a real chance of wiping out the pest.
The screwworm was pushed back to south of Panama, and for decades, sterile fly releases acted as a border for the screwworm. But, three years ago, flies got past that border and have been inching their way to the U.S. ever since.
It’s still unclear how the fly made it over the sterile fly border. But multiple factors could have played a role.
First, sterile flies aren’t a perfect solution, according to people like Miller. They do work, but some think they might be better-suited as part of a larger response because of their shortcomings.
“You just have to overwhelm them. They don’t have the numbers. It’ll work if you’ve got the numbers. But they’re releasing a hundred-million a week. They need about 600 million a week," Miller said. "They don’t have them. They’re not going to have them for about three to three and a half years.”
Second, it’s tough to coordinate with other countries, said Hubbell. Because policies and policymakers change, coordinated efforts can be complicated.
Third, migration, globalization and trade could play a factor in this, according to Hubbell. It’s possible a cow infected with screwworm slipped through the cracks or another infected animal made it past the sterile fly border.
The USDA did not provide a comment about the spread of screwworm by deadline.
The current response has been mainly focused on reporting and sterile fly releases, according to Miller. The agriculture commissioner said he doesn’t like that the USDA is predominantly focused on sterile flies when another effective method exists.
“We have a very efficient system… It’s a USDA proven program, they’ve used it for about eight years. It’s called the SWASS system, S-W-A-S-S, Screwworm Adult Suppression System. Just to boil it down to simple form, it’s a fly bait, just like you can buy from the hardware store,” Miller said.
“We put it out in the 70s and 80s and it killed 80 to 95% of the flies. With a suppressed population then you can come in with the sterile flies and they work,” he continued.
According to Miller, better reporting standards that incentivize communication between cattle ranchers and agencies is also a critical component to the ongoing response.
The USDA has been investing in sterile fly infrastructure so they can release more, according to its website. They are also working on creating technology that ensures all irradiated flies are males. This would effectively double the sterile fly output.
Arkansas has also taken steps to prevent the pest.
Cows coming into Arkansas from a screwworm “infested zone” in Texas need to be checked by a veterinarian before entering the state. Of course, Texas cattle will still come into Arkansas, according to Michelle Bufkin Horton, Arkansas Cattlemen’s Association vice president .
“By no means is the border from Arkansas to Texas closed,” she said. “[We’re] just adding a precaution of if something is coming out of a place that has New World screwworm cases, that it’s been looked at by a veterinarian to confirm that they’re not bringing it over the line to Arkansas.”
A spokesperson for the Arkansas Department of Agriculture says enhanced reporting that allows veterinarians to upload photos, location information and case descriptions is being used in the response. The spokesperson also highlighted partnerships with other industry groups, like the Arkansas Farm Bureau.
Keeping screwworm out of Arkansas is crucial. Hubbell said Arkansas just doesn’t have the beef processing infrastructure of Texas, so the state’s cattle ranchers rely more on transporting cows than Texas does.
According to Horton, beef consumers won’t be affected by the screwworm outbreak. Only safe meat is sent to be processed, and there are regulations in place to ensure beef quality and safety, she said.
