Flies feeding on cow tears transfer eye worms to Oregon woman

Thelazia gulosa - Photos Courtesy OHSU

PORTLAND, Ore. – It was one of the most interesting calls Dr. Erin Bonura has ever received while at Oregon Health and Science University (OHSU).

"'This patient has worms coming out of her eye. What are we going to do?'" Bonura said, remembering the call.

Researchers say they have identified the first human case of Thelazia gulosa - a worm that normally infects cattle. The patient pulled 14 of them out of her left eye in August, 2016.

Abby Beckley is from Brookings, a small town on the southern Oregon coast. She was on a fishing boat in Alaska when she removed the first worm from her eye.

“I looked down and on my finger was a worm. It was squiggling around for like five seconds and then it died,” Beckley told KATU News partner, KTVL.

She had been fishing on the boat for three weeks. Beckley pulled four more worms out of her eye before seeing a physician.

“It went from, ‘Okay maybe one just fell into my eye.’ To, ‘Oh my gosh, I have worms in my eye,’” Beckley said.

Bonura, OHSU's Assistant Professor of Medicine (Infectious Diseases), first learned of the worms when she got a call from a doctor in Southern Oregon.

“We take consult cars from around the state, from southern Washington, and northern California. I took a call from a physician in Oregon who said he had a friend of his son who had worms coming out of her eye, what should we do about it?” Bonura said.

Beckley came to OHSU later that month to meet with experts. Doctors were able to pull out one worm using something like a pair of tweezers. Bonura says Beckley pulled most of the worms out herself.

“She was very good about removing them herself. She was the best person for the job,” Bonura said. “When she did, she used her two fingers and pulled them straight out, as much as I can tell.”

After a few weeks, all of the worms were gone and Beckley’s symptoms went away, but Doctors still didn’t know what they were dealing with.

Bonura sent a sample to the Centers for Disease Control to identify the worm.

“It was a little bit hard because I couldn't give her right away a prognosis. How are we going to treat this? We didn't know what the worm was, so that's a little unnerving in the beginning,” Bonura said.

Researchers learned within a few weeks that this was a Thelazia worm, but had trouble figuring out the exact species. There have only been ten recorded human cases of Thelazia worms in the U.S. and none in the past 20 years. They are common in animals in North America.

Bonura says it took several months before researchers with the CDC positively identified the worm from Beckley’s eye as Thelazia gulosa. Researchers went back to German publications from 1928 to finally crack the case. This is the first time Thelazia gulosa has been recorded in a human.

How did it get into Beckley’s eye?

Bonura’s best guess brings us back to southern Oregon, where Beckley had been working on a ranch.

Thelazia gulosa is commonly found in cow eyes. Bonura says a certain type of fly that is known to feed on cow tears may have picked up the worm, then transferred it to Beckley by landing near her eye.

“Most people don't remember when it happened, it was just a chance encounter with that fly,” said Bonura.

Two-and-a-half years later, Beckley is doing well.

Bonura helped with a paper in the American Journal of Tropical Medicine and Hygiene which was published Monday. She has since added this story to the lectures for her medical students.

Human infections from worms like this are more common in developing countries. Bonura says not to worry about getting infected yourself.

“I don't want people to worry about this. This is not something you need to change your behavior about, it's unlikely that you would be infected,” she said.

Instead, she says be excited about how interesting it is.

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