While examining her eye, Beckley was able to remove a thin, half-inch-long translucent worm with her fingers. She had recently started working on a fishing boat in Alaska when her eye first began to feel irritated, as if there was an eyelash she couldn’t remove. However, the deposited larvae did grow into adult worms and begin wriggling around on the surface of the Beckley’s eye. Luckily, the cattle eyeworm can’t easily reproduce in humans - and didn’t in Beckley’s case. One fly carrying cattle eyeworm larvae may have briefly landed on the patient’s eye.

The cattle eyeworm is spread from cow to cow by flies that suck on cow tears and pick up worm larvae in the process. The best Bonura and her colleagues can guess is the patient, Abby Beckley, may have been infected while being near cows or horses in the rural fields near her family’s home. This was the first case of a person being infected with a Thelazia worm in the U.S.

Before this case, there were just 10 known incidences of humans being infected with a Thelazia worm in North America, but none of those cases involved the species gulosa. Worms in the family Thelazia are a common parasite in North American cattle, but are rarely spread to humans.

One of 14 eyeworms removed from Abby Beckley's eye.

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