The parasite that turns your eyes into a hotel for worms

Over in the United States, a woman contracted a parasite that turned her eyes into “a breeding ground for squiggling worms”. No, thanks.



For what is believed to be only the second time ever, a human has contracted an ocular parasite that turns the eyes into a breeding ground for squiggling worms.

While this is only the second documented case in humans, it’s worth noting that both cases have occurred within two years of each other.

A 68-year-old from Nebraska is our patient zero, who marked California’s Carmel Valley with her running shoes. On the trail one day, she ran into a small swarm of tiny flies.

“She recalls swatting the flies from her face and spitting them out of her mouth,” the researchers explain in their case report.

The following month, the Nebraskan noted irritation in her right eye, and after flushing her eye, a worm flopped into the basin.

She found another in her eye (which she was also able to extract), and the next day she visited an ophthalmologist, who found a third.

A couple of weeks later, she returned home to Nebraska, still feeling continued irritation and a “foreign body sensation” in both eyes.


021 parasitic eyeworm 1

T. gulosa female worm, revealing ovaries containing spirurid eggs and larvae at bottom-left. (Bradbury et al., Clinical Infectious Diseases, 2019)


Later, she found a fourth. It’s probably worth mentioning that the previous case discovered 14 worms squatting in her eye.

As Science Alert noted, “Analysis of one of a nematode sample collected from the Nebraska patient confirmed her case was the second known instance of the parasitic T. gulosa infection (aka the cattle eyeworm), and revealed a literal litter of surprises besides.”

The authors of the study took it further, “…eggs containing developed larvae were observed in utero, indicating that humans are suitable hosts for the reproduction of T. gulosa.”

Fun. So how did this happen? Well, theThelazia eyeworms are oft-transmitted between animals by species of flies.

Most commonly, in the case of the above eye worm, they are known to carry the infection to cattle. Several infections have been identified in the US, Canada, Europe, and ultimately, the land of flies and cattle, Ozstrayalia.

Bitterly, the authors leave us on a cliffhanger, noting that testing for the parasites are “not be considered a strict priority in these regions” and “the reasons for this species only now infecting humans remain obscure,” the authors explain.



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