A shingles outbreak can nearly quadruple the risk of developing MS in the following year, but the overall risks remain small, according to research conducted inChina. Viruses are thought to play a role in triggering MS, and herpes zoster virus, which causes shingles, is one of the viruses previously implicated. But the new results reported in the Journal of Infectious Diseases are the first to quantify the risk.
Shingles is an exceptionally painful, blistering skin rash caused by the herpes zoster virus, the same virus that causes chickenpox. In many patients who suffer chickenpox in childhood, the virus is not eradicated from the body, but lies dormant for years or decades, until it is prompted to start replicating by environmental conditions, stress or infectious diseases.
Epidemiologist Herng-Ching Lin ofTaipeiMedicalUniversityinTaiwanand colleagues studied 315,550 adults with herpes zoster and a control group of 946,650 healthy controls, tracking them for a year to monitor for the development of MS. After adjusting for family income and geographic region -- both of which are known to play a role in MS -- the researchers found that the group with herpes zoster outbreaks was 3.96 times more likely to develop MS than the control group. On average, MS developed about 100 days after the shingles episode.
The authors noted, however, that MS has a lower incidence in Asian populations than in Western ones, so it may be difficult to extrapolate their findings to the rest of the world.