Studies show ME could be caused by stomach virus

A stomach virus could trigger the condition myalgic encephalomyelitis (ME), BBC News reported September 13 2007. Also commonly known as chronic fatigue syndrome (CFS), the condition is associated with symptoms such as general aches and pains, tiredness, and problems with concentration.

According to the BBC, “The finding may help explain why many patients with ME often have intermittent or persistent gut problems, including indigestion and irritable bowel syndrome.”

The story is based on the results of a case-control study in the USA, which showed that people with CFS are more likely to have a chronic gastric enteroviral infection than healthy volunteers. The study was small, and conducted in one geographical region. As the authors themselves state, more research in people from different geographical regions is needed before we can fully conclude that gastric viral infections are a cause of CFS.

The possible causes of this complex condition are poorly understood; however there is often the suggestion from doctor’s observations that it develops following an illness. Therefore, this research does open up a new avenue for study into this condition.

Where did the story come from?

Doctors John kai-sheng Chia and Andrew Y Chia from EV Medical Research in California conducted this research. The study was funded by a grant from Gilead Sciences. A patent application is on file for the testing of the presence of enteroviruses to indicate the presence of CFS. The study was published in the peer-reviewed medical journal: Journal of Clinical Pathology.

What kind of scientific study was this?

The study was a case-control study where stomach biopsies were performed on 165 people diagnosed with CFS. The biopsy samples were processed and purified and the researchers determined whether they contained a particular protein called VP1 that is found in the outer shell of enteroviruses  and viral RNA, which is genetic material. The presence of these would indicate a stomach infection.

The results from these tests were compared with similar tests that had been performed on biopsy samples from 34 healthy volunteers, and volunteers with other gastric disorders such as gastritis, inflammatory bowel disease, gastro-oesophageal reflux disease and stomach cancer.

What were the results of the study?

The researchers found that 82% of the samples from people with CFS showed evidence of viral infection compared with only 20% of samples from healthy volunteers. The researchers were not able to identify which type of virus was responsible for the infection.

What interpretations did the researchers draw from these results?

The researchers concluded that people who have CFS show evidence of gastrointestinal viral infection. The researchers say their results suggest that a ‘significant subset’ of people with CFS may also have a chronic form of enteroviral infection leading to a variety of symptoms. This group could be identified, they believe, through a stomach biopsy, and in preparation for it being approved have a patent pending for the method they used in the research. They say that although their discovery of a stomach infection doesn’t directly prove a similar infection in the brain, muscle or heart, “it opens up a new direction in the research for this elusive disease”.

What does the NHS Knowledge Service make of this study?

We should be aware of the following limitations when drawing conclusions about cause and effect from this study.

• The study was small and only conducted in one geographical environment. The study will need to be repeated in different populations before we can be sure that the level of enterovirus infection that was observed wasn’t simply a feature of this particular population.
• The researchers are unclear about exactly how their participants were selected. They state that 165 ‘consecutive patients’ underwent biopsies. It is not clear whether these patients underwent a biopsy specifically for this study or as part of routine investigations for gastric complaints. The latter approach would have meant the sample itself was biased towards those people having both CFS and gastric problems. In fact, the researchers themselves report that the majority of the patients had some gastrointestinal complaint. They say that without further research, they cannot be sure whether there results are not due to ‘a patient selection bias’.
• The researchers were not able to identify the exact enterovirus that they believe was causing the chronic infection in these patients. Further work is needed on this.

Overall, this study provides a starting point for further research into the gastric health of people with CFS. Larger studies in different regions and populations will need to be carried out before we can make any claims about the causes of this complex disease.

Sir Muir Gray adds...

Independent evaluation of this result would be essential before considering these results in greater depth.