Audrey Schuetz, M.D., Comments on First-Ever Case of Human Eye Worms

Thelazia gulosa worm. Image: CDC.

A recent article in HealthDay News reported on a case of an avid 26-year-old outdoorswoman from Oregon who became the first human ever infected by a type of eye worm previously seen only in cattle. The case was published in the American Journal of Tropical Medicine.

For days, the woman's left eye felt irritated. After about a week, she reached up and pulled a small worm off of her eye, said Richard Bradbury, a U.S. Centers for Disease Control and Prevention researcher and lead author of a case report on the event. However, that wasn't the end of it. "A total of 14 worms were removed from her left eye over 20 days. They weren't able to remove them all at once. They had to remove them as they became present and visible."

The worms were less than half an inch long. Known as Thelazia gulosa, the worms cause eye irritation but usually no permanent damage. While other worms from the Thelazia family have been found on human eyes before, this is the first time this specific worm has infested a person, Bradbury said.

Photo of Audrey Schuetz, M.D.
Audrey Schuetz, M.D.

According to Audrey Schuetz, M.D., Senior Associate Consultant in the Division of Clinical Microbiology in the Department of Laboratory Medicine and Pathology at Mayo Clinic in Rochester, Minnesota, the worms are transmitted by face flies, which carry the larvae in their mouth parts.

"In general, flies are attracted to the moisture and salt in our tears," said Dr. Schuetz, who wasn't involved with the study. "The larvae are introduced into the fleshy part of our eyes when the fly is feeding on our tear film, the moist part around our eyes."

Dr. Schuetz also commented that it is possible but generally unlikely for these worms to cause scarring of the cornea and even blindness if they saunter off the whites of an eye and into your field of vision.

"Folks worried about contracting eye worms can wear a hat with a net attached to protect their faces from flies," Dr. Schuetz said.

Kelley Luedke

Kelley Luedke is a Marketing Channel Manager at Mayo Clinic Laboratories. She is the principle editor and writer of Insights and leads social media and direct marketing strategy. Kelley has worked at Mayo Clinic since 2013. Outside of work, you can find Kelley running, traveling, playing with her kitty, and exploring new foods.