Parasitic worm normally found in amphibians and crustaceans in China may have scavenged nutrients from patient’s brain
A man who went to see his doctor after suffering headaches and experiencing strange smells was found to have been living for more than four years with a rare parasitic worm in his brain.
In the first case of its kind in Britain, the ribbon-shaped tapeworm was found to have burrowed from one side of the 50-year-old man’s brain to the other.
Doctors were left baffled after spotting strange ring-like patterns moving 5cm through his brain tissue in a series of scans taken over four years.
Surgeons only discovered the 1cm worm while carrying out a biopsy at Addenbrooke’s hospital in Cambridge and took it to parasite experts to be identified.
Geneticists at the Wellcome Trust Sanger Institute in Cambridge found the creature was a rare species of tapeworm known as Spirometra erinaceieuropaei.
Only 300 cases of infection by this parasite in humans have been reported since 1953, with only two previous cases identified in Europe.
The worm is normally found in amphibians and crustaceans in China and as it goes through its life cycle it later infects the guts of cats and dogs, where it can grow into 1.5-metre adult worms. Even in China, where the parasite is normally found, there have only been 1,000 cases reported in humans since 1882.
The unfortunate patient, who was of Chinese descent but lived in East Anglia, is thought to have picked up the parasite while on a visit to China, where he visited regularly. However, exactly how he came to be infected is not known, but he could have picked it up from infected meat or water and the worm then burrowed through his body to his brain.
Now scientists believe they have been able to learn new information about this rare parasite after studying its DNA.
Rather than living on the brain tissue of its unknowing victim, the parasite is thought to have simply absorbed nutrients from the man’s brain through its body as the worm has no mouth.
Dr Hayley Bennett said they hoped to use the result of the study to help diagnose infections in humans more quickly in the future and even find ways of treating it.
She said: “This worm is quite mysterious and we don’t know everything about what species it can infect or how. Humans are a rare and accidental host. for this particular worm. It remains as a larva throughout the infection. We know from the genome that the worm has fatty acid binding proteins that might help it scavenge fatty acids and energy from its environment, which may be one the mechanisms for how it gets its food.
“This genome will act as a reference, so that when new treatments are developed for the more common tapeworms, scientists can cross-check whether they are also likely to be effective against this very rare infection.” The research is published in the journal Genome Biology.
The patient first noticed something was wrong in 2008 when he began suffering headaches, seizures, memory flashbacks and strange smells.
After visiting his doctor, an MRI scan revealed a cluster of rings in the right medial temporal lobe.
He was given tests for a wide range of other diseases including syphilis, HIV and tuberculosis but tested negative for them all. Later scans showed the rings moving through his brain.
After undergoing two biopsies, surgeons found the worm moving around in his brain and removed it in 2012. The man was then given drugs to help treat the infection but he continues to suffer from problems associated with having had the worm living in his brain.
It is not known how he first became infected, but one source of infection is the use of frog poultice, a traditional Chinese remedy where raw frog meat is used to calm sore eyes.
“We did not expect to see an infection of this kind in the UK, but global travel means that unfamiliar parasites do sometimes appear,” said Dr Effrossyni Gkrania-Klotsas, one of the clinicians involved in the man’s treatment at Addenbrooke’s NHS Trust.
“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 characterise the parasite.”