A British woman has told how a volunteering trip to Madagascar turned into a nightmare after she picked up a nest of tapeworms - which burrowed into her brain.
Sherry Fuller, 40, from Leigh-on-Sea in Essex, had visited the country on a charity sanitation project.
But when she returned to England, she began to suffer searingly painful headaches that developed into seizures, involuntary jerks, and personality changes.
According to the Free Library, Sherry thought she might have cancer.
But, after about a year of tests, she found out the illness was caused by a nest of pork tapeworm larvae that had hatched in a cyst in her head.
It is thought Sherry picked up the worms while working with children during the project.
The lead-up to the diagnosis was a fraught time, and doctors at the Royal London Hospital initially said her symptoms could be HIV or TB.
But a consultant neurosurgeon eventually diagnosed neurocysticercosis, a rare condition in which a person becomes infested with pork tapeworm.
Sherry told the Daily Mail: "The larvae in my brain were about the size of a 5p which was why it was causing me a problem.
"The doctors gave me a worming tablet which kills the larvae."
Sherry reacted badly to her treatment, however, and it has taken her over two years to fully recover.
Ms Fuller suffered with "a lot of anxiety" as well as becoming "over-sensitive to noise".
She is now working to raise money for the charity Headway Essex, who care for survivors of brain injuries, and support them through their recovery.
Cysticercosis refers to tissue infection after exposure to eggs of Taenia solium, the pork tapeworm.
The disease is spread via the fecal-oral route through contaminated food and water, and is primarily a food-borne disease.
After ingestion the eggs pass through the lumen of the intestine into the tissues and migrate preferentially to the brain and muscles, where they form cysts that can persist for years.
In some cases the cysts will eventually cause an inflammatory reaction presenting as painful nodules in the muscles and seizures when the cysts are located in the brain.
Symptomatic disease from Taenia solium cysts in the brain, as in Sherry's case, is referred to as neurocysticercosis and is the most common tapeworm infection of the brain worldwide.
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