Researchers have reported that people who experienced an attack of herpes zoster (usually manifesting as the skin rash known as shingles) were more than three times as likely to develop MS over the next year than individuals without such an attack, in a study using a large data set of Taiwanese people who are generally at lower risk for MS than those of European descent. This unique, large study warrants confirmation in other ethnic populations. Jiunn-Horng Kang, MSc, MD, Herng-Ching Lin, PhD, and colleagues (Taipei Medical University and Hospital) report their findings in The Journal of Infectious Diseases (2011 Jun 7 [Epub ahead of print]).
Background: Since initial exposure to numerous viruses, bacteria and other microbes occurs during childhood, and since viruses are well recognized as causes of nervous system damage and inflammation, it is possible that a virus or other infectious agent is the triggering factor in MS. More than a dozen viruses and bacteria, including measles, canine distemper, human herpes virus-6, and Chlamydia pneumonia have been investigated to determine if they are involved in the development of MS. Recently, various types of evidence point in particular to an association between MS and the Epstein-Barr virus, a herpes virus known to cause infectious mononucleosis and other disorders. None of the infectious agents investigated to date have been proven to trigger MS. Read more about viruses and MS.
The varicella zoster virus is responsible for chicken pox. Even after an initial infection, the virus has the ability to remain dormant in the body and later re-emerge to cause the painful skin rash known as shingles, or other manifestations.
The Study: Investigators used the National Health Insurance Research Database, in which nearly all of Taiwan’s population is enrolled. They identified 315,550 people who had visited ambulatory care centers with a primary diagnosis of herpes zoster between January 2003 and December 2005. The team randomly selected 946,650 people as controls, who were matched with the study group in age, gender, and the year of their first ambulatory care visit. The investigators then determined how many patients in each group developed MS during the subsequent 12 months.
The results show that 29 people from the study group, versus 24 from the control group, were diagnosed with MS during the one-year follow-up period. The investigators calculated the risk of developing MS among the group who had an attack of herpes zoster to be 3.63-fold greater than that of the control group. The authors point out that the genetic background of the Chinese population studied makes it uncertain how this finding might translate to other populations. In addition, these interesting findings rely on there being no additional cases of herpes zoster attacks for which no medical care was sought, and no cases of MS either undiagnosed or misdiagnosed, the existence of which may or may not alter the outcomes of the study.
Read more about the National MS Society’s efforts to find the factors that trigger MS.