Americans may be more vulnerable than previously believed to a type of parasitic eye worm, according to two new studies published Monday.

One of the first cases found was in Oregon.

The studies, in the “American Journal of Tropical Medicine and Hygiene,“ report that the worm, previously seen only in cows, can now be spread to humans.

The patient was a 26-year-old Oregonian. She’d been riding horses in Gold Beach near a cattle farm.

First, her eye became irritated.

A week later, while she was on a fishing boat, she removed a small, translucent worm from her eye.

A transparent eye worm on the surface of a patient's conjunctiva.

A transparent eye worm on the surface of a patient’s conjunctiva.


Dr. John Hoyt

Over three weeks, 13 other worms were removed — each about a half an inch long. They lived between the eyeball and the eyelid skin.

An adult female eye worm.

An adult female eye worm.

Centers For Disease Control and Prevention

Dr. Richard Bradbury with the CDC said the worms are spread by flies that feed on eyeball tears.

“Humans very rarely get infected, because if a fly gets near your eye, you normally shoo it away,” he said. “But this particular patient must have been in an unfortunate position where for a few moments her hands were taken up doing something else.”

Humans have been infected by dog eye worms before. But this is the first case of cattle eye worm contamination in the U.S.

The patient’s eyesight was not damaged.