Abby Beckley in 2015 on a hike near her home in Bend, Oregon. She is the first human known to have been infected with a rare eye worm found in cows. Family Photo

Abby Beckley thought her left eye was irritated because of a stray eyelash. She rubbed her eye, flushed it with water, but when the discomfort remained, she peered into the mirror. She thought she saw a piece of clear fuzz. She pinched it with her fingers and pulled it out.

It was a worm. About half-inch long, translucent and threadlike. "It was alive and squiggling around," she recalled.

Beckley remained calm. The 26-year-old was a deckhand on a commercial salmon fishing boat in Alaska. Maybe a common but harmless salmon worm had fallen into her eye. At a local urgent care clinic, the clinicians did not know what to tell her, but they pulled out two more worms. An ophthalmologist pulled out another two.

Beckley became increasingly alarmed. She was not in pain, but her eye was red and inflamed. No one knew how to advise her, and she imagined the worst. Could she lose her vision? Could the worms crawl into her brain? Paralyze her face?

Luckily, her boyfriend's parents, both doctors, got her an appointment with an infectious disease specialist in Portland, Ore. They also reassured her the worms probably did not have the capacity to reproduce or crawl into her brain.

In the end, it was a team of scientists at the Centers for Disease Control and Prevention that solved Beckley's case, which took place in August 2016. Scientists at CDC's special lab that diagnoses parasitic diseases figured out she had been infected by a species of eye worm that had never before been found in a human. By the time her ordeal was over, 14 worms had been pulled from her eye.

Medical parasitologist Richard Bradbury identified the species by searching the medical literature and eventually finding an obscure journal written in German that was published in 1928. The case study about Beckley's ordeal was published Monday in the American Journal of Tropical Medicine and Hygiene.

"We never expected to see this particular species in a human," Bradbury said. Until now, this type of worm, Thelazia gulosa, had only been found in cattle.

Adult Thelazia gulosa removed from the eye of human on a person's finger. Picture: cdc.gov

Eye worms infect a variety of animals, but human infections are rare. The worms are transmitted to eyes by flies. The flies ingest the worm larvae, then land on an animal's eyes, where the flies feed on tears and other secretions. During this process, the flies deposit the worm larvae into the eye, where they grow into adult worms.

Eye worm infections typically occur in children and the elderly, experts said. Human infections have been reported in parts of Asia as well as in Russia, Italy, and France. The worms cause inflammation but symptoms go away if they are removed. In more serious cases, they can cause scarring of the cornea and even blindness. There have only been 10 other cases of eye worm infections in the United States, but they have not involved the cattle eye worm that infected Beckley.

Photos of Beckley's inflamed eye and one of her eye worms are now part of the official CDC Thelazia page. She made medical history because of bad luck.