Culprit Behind Man's Itchy Eye Turns Out to be a Dozen Sheep Bot Flies

On April 6th, according to reports from The New England Journal of Medicine, a 53-year-old man living in France was rushed to the emergency room after developing an unbearable itching sensation, which lasted for several hours, in his right eye. The man informed his doctors that he had been gardening earlier in the day near a horse and sheep farm when he felt a foreign object enter his eye.

Bot Flies in the Eye

When attending doctors performed an eye exam on the man, they were shocked to discover over a dozen mobile, translucent larvae squirming on his cornea and conjunctiva, as reported by the authors from the University Hospital Saint-Etienne, France.

The eye's cornea is the transparent outer covering that shields the front of the eye, while the conjunctiva is a membrane that lines the eyelids and white parts of the human eye.

The man was aptly diagnosed with external ophthalmomyiasis or an infestation of the outer structures of the human eye by the bot fly larvae, explain the authors, reported VerveTimes.

To remedy the condition, doctors had to remove the foreign organisms from the man's eyeball physically. Doctors were quick to remove each larva that infested his eyes using forceps.

According to the University of Florida, the larva belonged to sheep botflies or Oestrus ovis, a fly species that causes parasitic infections in sheep across the globe. Doctors presume that the man became infected with the fly larva when a fly flew into his eye and deposited the squirming larva.

The report's authors noted that the fly larva has "oral hooks" and "body spicules" that could have easily caused superficial abrasions on the man's cornea if left untreated.

What are Sheep Bot Flies?

Oestrus ovis, according to the University of Saskatchewan, is otherwise known as sheep nasal bot flies that can be found in sheep farming areas across the globe. It primarily infects sheep and goats but occasionally has been reported in ibex, camel, and people.

Adult sheep nasal bot flies reach roughly 12mm in length, dining a grey-brown color with small black spots on their stomach and covered with brown hair. On the other hand, the fly's larva is roughly 30 mm long and pale yellow with dark transverse stripes on its dorsal surface.

Its life cycle is direct. Adult females deposit larvae into sheep nostrils while flying past by squirting liquid containing about 25 first-stage larvae into the nose. The larva then migrates via the nasal passage to the frontal sinus of the sheep, where they develop into a third-stage larva that migrates back to the nostrils and is later expelled into the environment via the host's sneezing.

Human infection, on the other hand, with O. avis is rare. In these cases, the larva is deposited normally near the eyes or lips and can result in stomatitis or catarrhal conjunctivitis. Luckily, larva does not fully develop in human hosts; however, it is best to remove it as soon as possible.

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