Epidemiology of herpes zoster and its relationship to varicella in Japan: A 10-year survey of 48,388 herpes zoster cases in Miyazaki prefecture.

From 1997 to 2006, a total of 48,388 patients with herpes zoster, ranging from a 3-month-old girl to a 102-year-old woman, were monitored at the 46 dermatology clinics in the Miyazaki Prefecture, which has a population of about 1.2 million. The mean herpes zoster incidence was 4.15/1,000 person-years, ranging from 1.96 to 7.84/1,000 person-years among different age groups, and the herpes zoster incidence was significantly higher in females (4.58) than in males (3.67). The incidence by age group was 1.96-2.86/1,000 person-years below the age of 50 years, and it increased to 5.23-7.84/1,000 person-years in persons 50-59 and older, with a trough in the ages 30-39, forming the small and large peaks. Females showed a significantly higher incidence than males, and the difference between the sexes was small below age 40 but greater at 40-49, 50-59, and 60-69. The incidence of herpes zoster was highest in August and lowest in winter, mirroring the prevalence of varicella. The number of herpes zoster cases at 60 years and older increased more than in the population from 1997 to 2006, and this increased incidence of herpes zoster in the 60-69 years and older, especially in females, might have raised the rate in contrast to the stable incidence below the age of 60 years. This large-scale survey clarifies the epidemiology of herpes zoster by age, gender, and season in relation to the prevalence of varicella in the Miyazaki Prefecture in Japan.