A Woman From Oregon Is The First Person Ever Infected With This Gross Cattle Parasite — In Her Eye
A worm called Thelazia gulosa lives and breeds on cow eyeballs. But now it's been found in a human eye for the first time.
Two summers ago, Oregon resident Abby Beckley found herself standing in front of a mirror on an Alaskan fishing boat, pulling tiny worms out of her eye.
A few months later, scientists reviewing her case were shocked to discover that she had been infected with Thelazia gulosa, a parasite that typically lives and breeds on cow eyeballs.
“It's never been found in humans before,” Richard Bradbury, the parasitologist at the CDC who identified the worm, told BuzzFeed News.
Beckley, 28, was working on a salmon boat in Alaska in 2016 when she woke up one day with a pricking feeling in her left eye, like a stray lash lodged under her lid.
When the invisible irritant persisted for a week, Beckley, perplexed, decided to investigate. Standing at the mirror in the galley, she plucked at her eyeball, as if extracting a contact lens.
“I put my fingers in there in kind of a picking motion and I pulled out a worm,” Beckley told BuzzFeed News. “I looked at my finger and it was moving and I was shocked.”
Beckley said she woke up her bunkmate to show her the worm, a piece of tangled white fluff wriggling at the end of her index finger. “She confirmed I wasn’t crazy,” Beckley said.
Over the course of the next few days she pulled out about a half dozen more. “I was living with these things, and I’d just keep pulling them out when I’d feel them,” Beckley said.
In severe cases, Bradbury said, the worms could burrow beneath the eye surface to scratch the cornea, leading to blindness. But besides giving Beckley a mild case of pink eye, the infection did not cause any harm.
“It’s pretty wild,” James Maguire, professor of medicine at Harvard Medical School and infectious disease specialist at Brigham and Women’s Hospital, told BuzzFeed News. “If someone like this walked into my office and I was pulling worms out of their eyes, I’d be pretty impressed.”
After two unsuccessful visits to clinics accessible to the salmon fishing boat, Beckley flew home and visited specialists at the Oregon Science and Health University in Portland. The team extracted two worms and sent a preserved sample to the CDC. Over the next few weeks, each time she felt a twinge, Beckley would reach in and pull out another worm or two, to make a total of 14.
The worms likely entered Beckley’s system when a face fly — the parasite’s other host — settled near her eye, and wasn’t brushed away immediately. Beckley said she doesn’t own a farm, but often visits family and friends who have animals on the premises in Oregon.
“It was a random event,” Bradbury said. “I don't think people have to worry about this becoming more common.”
Thelazia worms morph through a handful of phases during their life cycle. This family of parasites spends half their lives on the eyeballs of horses, cows, and even yaks, and the other half in face flies that hum around the eyes and ears of farm animals.
Male and female adult worms live on the surface of the eye, and mate to produce larvae that live in tears. The larvae then hop a ride in face flies, and infect the next animal the flies visit.
“They’ll sexually reproduce on the surface of the eye. They'll find each other, and you know...it's very romantic,” Bradbury said.
There have been 10 reported instances of Thelazia infections in the US — nine in California and one in Utah — but all of those were caused by Thelazia californiensis, a species endemic to North America. There has never been a case of infection in Oregon until now.
“They’ll sexually reproduce on the surface of the eye. They'll find each other, and you know...it's very romantic.”
“I think she happened to be at the wrong place at the wrong time,” Rojelio Mejia, assistant professor of infectious diseases and pediatrics at the National School of Tropical Medicine at Baylor College of Medicine, told BuzzFeed News.
Mejia said that this case is a reminder that human parasites, which are usually seen in parts of the developing world, live in the US too. Recent research he has led has shown that certain hookworm and roundworm infections are flying under the radar.
Other eye parasites can be far more deadly, Maguire said. For example, the bite of the blackfly can cause “river blindness” after the parasite’s larvae travel to the skin and eye and trigger an inflammatory response. And deerfly bites can infect a person with “loa loa” worms that live on the surface of a person’s eye, Maguire said, requiring surgery to get them out.
Compared to those, he said, Beckley’s infection was tame. “It seems like a curiosity.”