An Oregon woman had 14 worms removed from her eye in the the first known human case of a parasitic infection spread by flies.
Scientists reported the case, from August 2016, in the American Journal of Tropical Medicine and Hygiene for the first time on Tuesday.
The translucent half-inch long worms were pulled from Abby Beckley’s eye after she was diagnosed with Thelazia gulosa.
The worms, many of which Ms Beckley pulled from her eyes herself, have been seen in cattle in the northern United States and southern Canada, but never before in humans.
They are spread by a type of fly known as “face flies.”
The flies feed on the tears that lubricate the eyeball, scientists said.
Ms Beckley had been horseback riding and fishing in Gold Beach, Oregon, a coastal, cattle-farming area.
After a week of eye irritation, she pulled a worm from her eye.
She visited the doctors, but removed most of the additional worms herself during the following few weeks.
Eye worms are seen in several kinds of animals, including cats and dogs, and they can be spread by different kinds of flies.
Two other types of Thelazia eye worm infections had been seen in people before, but never this kind, according to Richard Bradbury of the Centers for Disease Control and Prevention.