A horrifying video shows the moment doctors found a worm swimming in a teenage boy’s eye.
The unnamed youngster went into hospital complaining of pain and loss of vision in his right eye.
Eye specialists in the Mexican capital Mexico City examined the 17-year-old and could see a parasite moving in and out of holes it had burrowed into his iris.
The intruder in his eye was a worm that ‘moved freely’ swimming in his intraocular fluid, the watery liquid that fills the chambers of the eye.
It had been there for three weeks, causing agonizing pain and severe problems with his sight – and eventually had penetrated his retina.
The ophthalmologists, from the Conde de Valenciana Institute of Ophthalmologym, immediately operated on the patient, removing the eye’s lens to get to the worm.
Then they discovered that the worm had left holes beyond the iris and deep in his retina, causing permanent vision loss.
Located near the optic nerve, the retina, which is the thin layer of tissue that lines the back of the eye, plays a vital role in vision.
The medics successfully removed the worm after cutting it into several pieces. The tiny 3 millimetre parasite was identified as a trematode, a type of flatworm.
Infections can happen in humans and animals after trematodes are ingested from eating under-cooked fish, crustaceans, or vegetation containing their larvae.
They usually infect the gut when they invade humans, therefore the presence of the creature in the boy’s eye baffled doctors.
Dr Guzman-Salas, who examined the boy, said the boy, who is from a rural area of the country, had had ‘very, very bad luck’.
British pets and their owners are at risk of a parasitic eye worm that can lead to blindness from dogs imported from Europe, a study warned.
The parasite is spread by a species of fruit fly recently found in southern England, leading to fears it could spread to wild animals such as foxes that might act as ‘a reservoir’ if it gains a foothold.
But humans can get infected too as it can jump between species, according to research from the Veterinary Record.
Thelazia callipaeda also known as ‘oriental eye worm’ is increasingly common in Europe while the fruit fly Phortica variegata has been found in Gloucestershire, Kent and Berkshire.
The first known case of the eyeworm infection in the UK was found in an one-year-old male collie cross recently imported from western Romania just last July.
It was later found in a 12-year-old female wire hair fox terrier had been in Lombardia and an eight-year-old female West Highland white terrier taken to the Dordogne that summer.
All had a UK pet passport and the emerging infections highlights the danger the free movement of pets poses to animals and humans in the British isles.