Researchers suggest that increased levels of immune antibodies that fight Epstein-Barr Virus (EBV), the virus that causes infectious mononucleosis and other disorders, may be associated with an increased risk of developing multiple sclerosis. Alberto Ascherio, MD, DrPH, and colleagues (Harvard School of Public Health, Walter Reed Army Institute of Research) reported their findings in the March 26, 2003 Journal of the American Medical Association.
The study reports on 83 cases (defined by the researchers as definite or probable MS), among 3 million military personnel, who were granted temporary or permanent disability because of MS, and whose blood samples had been previously collected and stored by the U.S. Department of Defense. For each of these 83 cases, the researchers identified the earliest available blood sample plus up to two additional samples collected before the onset of MS, and the first sample collected after the onset of MS. Using those stored samples, the researchers looked for elevated levels of immune antibodies (indicating prior exposure to an infectious agent) against EBV and another virus for comparison, searching for an association between these viruses and MS. For each case of MS, two control cases without MS were also studied.
Epstein-Barr virus is one of the most common viruses in the world, and by age 40 as many as 95 percent of adults in the U.S. show signs of having been exposed to it. In this study, the researchers found that all cases of MS and probable MS, and 96% of the controls, had evidence of previous EBV exposure. Antibodies to EBV were consistently higher in people who later developed MS than in controls. The risk of MS increased with increasing levels of antibodies. The association was present in samples collected five or more years before the onset of MS. There was no difference in antibodies to the second virus studied.
For many years scientists have been searching for possible links between
MS and infectious agents including EBV. This interesting study, by a respected
group of researchers, adds to this body of work. So far, a causal relationship
has yet to be established between any infectious agent and MS. It is possible
that the immune dysfunction that leads to MS causes abnormal findings in
immune responses to various infectious agents. It is also possible that
infections of late childhood influence the immune systems of genetically
susceptible individuals, altering defenses and later attacking the body’s
own brain and spinal cord tissues. Further research into infectious agents
and MS, which is ongoing, should shed further light on these questions.
© 2003 The National Multiple Sclerosis Society