A 35-year-old man in India endured eight months of redness and blurry vision in his left eye—until doctors discovered the shocking cause: a live worm wriggling inside his eyeball.
According to a case report in the New England Journal of Medicine, examination revealed a bloodshot, inflamed eye with a dilated, unresponsive pupil. Vision in the affected eye had dropped to 20/80. Under the scope, doctors spotted the tiny intruder sluggishly moving in the vitreous—the jelly-like substance inside the eye.
To remove it, ophthalmologists performed a pars plana vitrectomy, a procedure typically used for retinal disorders. They made small incisions in the sclera (white of the eye) and used a hollow, needle-like suction device to extract part of the worm’s tail, pulling it out alive. Under the microscope, the culprit was identified as Gnathostoma spinigerum, a parasitic worm native to India.
This parasite’s life cycle typically involves wild and domestic cats or dogs as primary hosts, passing eggs through their feces. The larvae infect freshwater plankton, which are eaten by fish or amphibians—then by the primary host again. Humans become accidental “dead-end” hosts by eating undercooked infected meat or fish. Once inside the body, the larvae can migrate to the skin, organs, or even the brain. Rarely, they invade the eye.
In this case, the man had no other systemic symptoms. Imaging scans showed no further spread. After the worm’s removal, doctors prescribed corticosteroids to reduce inflammation and anti-parasitic medication to prevent recurrence.
Eight weeks later, his discomfort improved—but his vision did not fully recover due to a cataract, a common complication of the surgery.
While rare, gnathostomiasis is a reminder of the risks of eating undercooked fish, poultry, or exotic meats—and of the bizarre journeys parasites can take through the human body.