Scientists sequence brain-dwelling tapeworm

A parasitic worm living in your brain -- it's the stuff of nightmares. But for a few unlucky people, it's a reality. Recently, it was the reality for one man in the United Kingdom.
The man's brain housed the rare tapeworm, Spirometra erinaceieuropaei, for four years. The infection was only the 300th occurrence -- only the second in Europe -- since the peculiar parasite was first discovered in 1953. Now, the 300th tapeworm to invade a human brain has become the first to be genetically sequenced.
Although much of it is repetitive, the species' newly sequenced genome is ten times longer than other tapeworm genomes. Scientists hope analyzing it will help them better understand the strange worm's life cycle and invasion strategies -- and also how to better combat its presence with modern medicine.
"For this uncharted group of tapeworms, this is the first genome to be sequenced and has allowed us to make some predictions about the likely activity of known drugs," Dr. Matt Berriman, a researcher at the Wellcome Trust Sanger Institute, said in a press release. "The genome sequence suggests that the parasite is naturally resistant to albendazole -- an existing anti-tapeworm drug. However, many new drug targets that are being explored for other tapeworms are present in this parasite and could offer future clinical possibilities."
Berriman is the lead author of a new study on the worm, which was published this week in the journal Genome Biology.
Scientists believe the tapeworm invades the brains of patients who consume infected freshwater crustaceans or the raw meat of reptiles or amphibians. People may also become infected when using a raw frog as a poultice to soothe sore eyes, an ancient Chinese remedy. The infection is most common in Asia. This particular species of tapeworm doesn't ingest the host's tissue -- it is without a mouth -- but simply absorbs nutrients from the brain.
Scientists first noticed the strange worm-like mass in brain scans after the 50-year-old man of Chinese descent, but who lives in East Anglia, continued complaining of headaches. Over a series of scans, they watched the worm move from right side of the brain to the left. They finally extracted it in a biopsy and sent the worm off to geneticists at Trust Sanger.
"We did not expect to see an infection of this kind in the UK, but global travel means that unfamiliar parasites do sometimes appear," explained Dr. Effrossyni Gkrania-Klotsas, study author and physician at Addenbrooke's Hospital's the Department of Infectious Disease in Cambridge. "We can now diagnose sparganosis using MRI scans, but this does not give us the information we need to identify the exact tapeworm species and its vulnerabilities."
"Our work shows that, even with only tiny amounts of DNA from clinical samples, we can find out all we need to identify and characterize the parasite," Gkrania-Klotsas added. "This emphasises just how important a global database of worm genomes is to allow us to identify the parasite and determine the best course of treatment."