Africa: Genome of Tapeworm Found in Man's Brain Sequenced

By Geoffrey Giller

Researchers have sequenced the genome of a rare, ten centimetre-long, ribbon-shaped tapeworm that had been travelling through a man's brain for four years in a move that could lead to new treatments for tapeworm infections.

Tapeworms usually infect the gut, causing symptoms such as weakness, weight loss and abdominal pain. But the larvae of some species can reach the eyes, brain and spinal cord. The species in this case, Spirometra erinaceieuropaei, is one such parasite.

Human infections caused by the larvae from this and closely related species are known as sparganosis. Although these species are found worldwide, such medical cases are most common in Asian countries such as China, Japan, South Korea and Thailand.

Other tapeworm species have a greater worldwide impact, for example causing neglected tropical diseases such as seizure-causing neurocysticercosis and potentially fatal alveolar echinococcosis.

In the case at the heart of the new research, a man of Chinese ethnicity living in the United Kingdom but who frequently visited China sought treatment in 2008, complaining about headaches, seizures, memory loss and occasional episodes of altered smell.

An MRI scan showed small lesions in the man's brain. However, numerous tests for everything from HIV to tuberculosis came back negative.

Doctors monitored the lesions for four years and found something strange: they moved around. Only when doctors operated on the man in 2012 did they discover the ten centimetre-long tapeworm living in his head.

The reason it took so long to diagnose, says Hayley Bennett, a researcher at the Wellcome Trust Sanger Institute, United Kingdom, and the lead author of a paper on the research published last week (21 November) in Genome Biology, is that infection by this particular type of worm is exceedingly rare.

"That was the first time this worm has ever been seen in the UK," she says. "I think the clinicians were pretty surprised."

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Africa: Genome of Tapeworm Found in Man's Brain Sequenced