Woman runs through swarm of flies on trail, comes back with eye worms

Breathe easy: Eye worms are super rare.

woman worm in eye
Adam Drobiec / EyeEmGetty Images
  • According to a case report published in the journal Clinical Infectious Diseases, a woman who ran through a swarm of flies on a trail run developed an eye infection due to Thelazia gulosaeye worms that generally infect cattle.
  • This is the second reported case of the Thelazia eye worms in humans.
  • While you probably don’t need to worry about picking up a case of the eye worms yourself, there are some eye safety tips you should know if you get any foreign object into your eye on a run.

    In early February of 2018, a woman was running on a trail in Carmel Valley, California—an area known for cattle ranching. The 68-year-old from Nebraska noticed some irritation in her right eye following a trail run in which she encountered some flies.

    About a month later, in early March, she noticed irritation in her right eye. The woman flushed her eye with water, when she noticed the likely source of irritation: a half-inch transparent worm in her right eye.

    She flushed it out, but then noticed a second worm in her eye, which she removed, too. The next day, she went to an eye doctor, who found and removed a third worm, as her case report published in the journal Clinical Infectious Diseases reported. The doctor—who sent the worm out for testing—recommended she continue to flush her eye, and also to use an antibacterial ointment to avoid infection.

    A few weeks later, when she went home to Nebraska, she underwent an additional eye exam, where her eye doctor told her she had mild conjunctivitis—an inflammation of the membrane that covers the surface of eye and inner eyelids and causes swelling, redness, discharge, and itching and burning. No additional worms were found during the exam, but shortly, she found another one, bringing the total up to four.

    It turns out, the creatures were Thelazia eye worms, which are typically found in cattle. This was just the second reported case of the eye worms in humans, according to the case study by the Centers for Disease Control and Prevention (CDC).

    The Thelazia eye worms are transmitted by flies that feed on the tears of their animal hosts, biologist Sarah Sapp, P.h.D., of the Division of Parasitic Diseases and Malaria at the CDC’s Center for Global Health explained to Runner’s World. The eye worm larvae are transmitted when that infected fly feeds on a new animal host. As the fly feeds near the eye tissues, larvae leave the fly host, enter the tissues surrounding the new host’s eyes, such as eyelids and tear ducts, and develop into adult worms there.

    “The patient reported encountering a large swarm of flies while running, so that was the likely source of exposure,” said Sapp.

    If you hit the trails often, chances are pretty good that you will encounter some flies on the run. But do you need to freak out about coming back with a case of eye worms?

    “The most important thing to remember is that human Thelazia infections in North America are extremely rare, so there is no need to panic,” Sapp said. Again, this case report was only the second known case in humans.

    Chances are high, though, that at one point or another you will get something in your eye on a run, even if it’s not a fly filled with eye-worm larvae. So in that much more likely situation, what’s your best course of action?

    The best thing you can do if you get something in your eye is to find the closest clean water source, like a sink, drinking fountain, or bottled water to flush your eye with.

    You should try to get whatever is irritating your eye out by flushing, not by rubbing, John Womack, O.D., the chief medical officer at Family First Vision Care at West Point Optical Group in Jacksonville, Florida, told Runner’s World. Though rubbing your eyes is the knee-jerk reaction, more particles from your hand can get in your eye, or the particles can move move around more, causing further irritation or damage to your eye.

    If no clean water is available, Womack suggests continued blinking, which can help force out the debris—or in some cases, lodge it deeper in your eye, which can temporarily ease the discomfort until you are able to flush it out later. You can also keep that eye closed until you can find a clean source of water or saline solution to flush your eye.

    And if you wear contacts, he suggests runners carry little bottle of Blink or another kind of artificial tear that’s safe for contact lenses. (If you don’t have a way to carry it with you, keeping it in your car is better than nothing, as you could return to your car to rinse your eye.) If something is still bugging you after rinsing, or you aren’t carrying a rinsing agent, you should remove your contact (with a clean hand) to prevent the particle getting stuck under your contact and causing further irritation.

    If the irritation persists after flushing your eye, Womack suggests heading to your eye doctor to let a pro look at your eye and remove the particles. He has removed everything from bugs and bug legs to sand, glass, and rocks from runners’ eyes.

    Your regular eye doctor is your best bet for this, but if it happens after regular business hours—say, your weekend trail run—an urgent care clinic can still help you flush the irritant out. You still may need to follow up with your eye doctor the next day if the clinic doesn’t have the proper tools to remove the particles or if the irritation persists.



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