Overview

In a rare and concerning medical case, a 35-year-old man from rural India sought medical attention for blurry vision, leading to the discovery of a live parasitic worm within his eye. The case, recently documented in the New England Journal of Medicine, highlights the potential for parasitic infections to affect ocular health and even cause vision loss.

The Parasite: Gnathostoma spinigerum

The parasitic worm identified was Gnathostoma spinigerum, a nematode typically found in cats and dogs. Humans become infected through the ingestion of raw or undercooked meat – specifically freshwater fish, poultry, snake, or frog – in regions where the disease, known as gnathostomiasis, is endemic. The patient in this case had consumed both freshwater fish and poultry, according to MedPage Today.

Gnathostomiasis can cause a range of health problems, and, as this case demonstrates, can have severe consequences for vision. According to Abdhish Bhavsar, MD, a clinical spokesperson for the American Academy of Ophthalmology and a retina specialist at Retina Consultants of Minnesota, “Gnathostomiasis is one of several parasites that can infect the eye and the retina.”

Dr. Bhavsar further explained that these worms vary in size, with some being small enough to travel within the retina or subretinal space – the area under the retina – possibly causing significant damage and even blindness.

Symptoms and Diagnosis

The patient initially presented with blurry vision. A physical examination revealed conjunctival injection, indicating inflammation of the conjunctiva (the membrane lining the eyelid and covering the white part of the eye).A fundoscopic evaluation – a test to examine the back of the eye – revealed a worm “moving sluggishly” in the posterior segment of the eye.

Treatment: Pars Plana Vitrectomy (PPV)

Doctors successfully removed the worm using a surgical technique called pars plana vitrectomy (PPV). The American Academy of Ophthalmology describes PPV as a procedure used to manage various retinal and vitreous conditions. It involves removing the vitreous gel – the clear, jelly-like substance filling the eye – to access and treat the retina and other internal structures.

Microscopic examination of the extracted worm confirmed its identity as a larval-stage Gnathostoma spinigerum, characterized by a cephalic bulb, thick cuticle, and well-developed intestine.

Preventing Gnathostomiasis

The primary method of preventing gnathostomiasis is to avoid consuming raw or undercooked meat, particularly freshwater fish, poultry, snake, and frog, in regions where the parasite is prevalent. Thorough cooking kills the larvae, rendering the meat safe for consumption.