(RxWiki News) For decades, common medical wisdom about shingles held that it is a one-time experience for virtually everyone it strikes. But recurrences may be much more common that doctors have long suspected.
Until recently it was believed that after one incident of inflammation from the herpes zoster virus, which causes shingles, most people were then immune to future recurrences.
The only patients susceptible to another outbreak were thought to be those with compromised immune systems, but it turns out that recurrence rates among all patients are about the same as the rates of first-case shingles.
"If you experienced shingles once, future outbreaks are possible."
A research team at Olmsted Medical Center in Rochester, led by Barbara Yawn, M.D., analyzed the medical records of nearly 1,700 shingles patients between 1996 and 2001, following them for up to 12 years to see if they had been treated for a second episode. The data showed the recurrence rate was over 5 percent, the same rate an age-matched cohort would be expected to experience a first case of shingles; and some patients had experienced as many as three recurrences.
"It's been thought that recurrences were limited to people with compromised immune systems, for instance from chemotherapy or bloodborne malignancies, but this is not the case," Dr. Yawn said. "Recurrence was prevalent in the immunocompetent population. We were very surprised by the results."
Dr. Yawn notes that the average length of time these patients were followed was eight years, and that if they were followed throughout their lives the recurrence rate would likely be much higher than five percent.
The study also found that women were more likely than men to have a recurrence, and the intensity and duration of pain during the first episode was also significant.
Those who had experienced pain lasting more than 30 days after the initial onset of shingles were more likely to face a recurrence, particularly surprising given the protection that a first case was presumed to give. Age did not appear to be a factor; older patients were not more susceptible to repeated episodes.
Findings from the study were published in the February 2011 issue of Mayo Clinic Proceedings.