Fourteen tiny worms removed in 2016 case of Thelazia gulosa, a parasitic infection spread by flies and previously seen only in cattle

This article is more than 2 years old

This article is more than 2 years old

An Oregon woman who had worms coming out of her eye is being called the first known human case of a parasitic infection spread by flies.

Fourteen tiny worms were removed from the left eye of the 26-year-old woman over a 20-day period in August 2016 before her symptoms dissipated. The worms were translucent and each less than half an inch long. Scientists reported the case on Monday.

The woman was diagnosed with Thelazia gulosa, a type of eye worm seen in the northern United States and southern Canada – but only in cattle. It is spread by flies that feed on eyeball lubrication.

The woman had been horseback riding in Gold Beach, Oregon, in a cattle farming area. After a week of eye irritation, she pulled a worm from her eye.

In a study published in the American Journal of Tropical Medicine and Hygiene, researchers said North Americans may be more vulnerable than previously understood to such infections.



If the worms remain in a person’s eye for a prolonged time, they can cause corneal scarring and even blindness, according to the researchers.

“Cases of eye worm parasitic infections are rare in the USA, and this case turned out to be a species of the Thelazia that had never been reported in humans,” said study lead author Richard Bradbury, who works with the CDC’s Division of Parasitic Diseases and Malaria.

Previous cases of eye worm infections have been reported worldwide, predominantly in Europe and Asia and in rural communities with close proximity to animals and with poor living standards, the researchers said.

Eye worms are found in a variety of animals including dogs, cats and certain wild carnivores.