New virus is not linked to chronic fatigue syndrome, suggests UK research
New UK research, published in PLoS ONE , has not reproduced previous findings that suggested Chronic Fatigue Syndrome may be linked to a recently discovered virus. The authors of the study, from Imperial College London and King's College London, say this means that anti-retroviral drugs may not be an effective treatment for people with the illness.
An estimated three in 1000 people have Chronic Fatigue Syndrome (CFS), or myalgic encephalomyelitis (ME), experiencing severe physical and mental fatigue that is not alleviated by rest, together with other symptoms such as muscle pain, headache, joint pain and depression. Diagnosing CFS is difficult, as symptoms vary and there is no standard test. The fundamental cause of CFS is unknown and it is usually treated using rehabilitation techniques such as cognitive behavioural therapy or graded exercise therapy.
In October 2009, a group of US scientists published research in the journal Science that suggested that a recently discovered virus called XMRV could be linked to CFS. In their study, 68 out of 101 patients with the illness and 8 out of 218 healthy controls appeared to be infected with the virus. However, in today's study, researchers found no evidence that patients with CFS had the XMRV virus, after analysing tissue samples from 186 patients with CFS using sensitive molecular testing techniques.
This more recent analysis showed no molecular evidence for XMRV in any of the samples from CFS patients. The researchers say this means that anti-retrovirals should not be used to treat CFS, as they would be unlikely to have an effect on the symptoms. However, several labs in the US now offer CFS patients treatments based on the earlier findings that linked the condition with XMRV.
"We are confident that our results show there is no link between XMRV and Chronic Fatigue Syndrome, at least in the UK. The US study had some dramatic results that implied people with the illness could be treated with anti-retrovirals. Our recommendation to people with Chronic Fatigue Syndrome would be not to change their treatment regime, because our results suggest that anti-retrovirals would not be an effective treatment for the condition," said Professor Myra McClure, one of the authors of the study from the Division of Medicine at Imperial College London.
After reading the US study, clinical researchers from King's College London sent blood samples from 186 CFS patients to the Imperial Retrovirology Laboratory team. King's has been running an NHS service for CFS patients for nearly twenty years, and the previously stored samples came from patients had been fully investigated and examined, meaning that CFS was the correct diagnosis. The Imperial scientists extracted the DNA from the samples and analysed it using PCR. The scientists analysed control samples of water at the same time to ensure there was no contamination. They also looked for a specific marker fragment of human DNA in the sample to make sure the technique was working.
The water controls contained no DNA, showing that the samples were not contaminated. All the test samples, from patients and healthy controls, contained the human DNA they looked for, suggesting the technique was working well.
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