Introduction

Dr. Edgar Hope-Simpson, a premier herpes zoster epidemiologist, fittingly described the allure and difficulties of herpes zoster epidemiology when he noted that “herpes zoster is fascinating because it arrives unpredictably … and is difficult to explain” (Hope-Simpson, 1965). Epidemiology seeks to explain and comprehend diseases by studying the characteristics of diseases in populations. Those characteristics include morbidity, mortality, incidence and prevalence rates, and risk factors. The objective of this chapter is to summarize these descriptive and analytical data on the epidemiology of herpes zoster to help the reader better understand this fascinating disorder.

The sources of zoster epidemiological data include cohort studies, case-control studies, large case series and case reports. Cohort studies have the strongest research design and will be emphasized, where available, in the presentation of descriptive and analytical information about zoster. Large, multi-year cohort studies of zoster in the general population are summarized in Table 12.1. The populations in these studies were mostly composed of immunocompetent individuals but did include a small percentage of immunosuppressed individuals. All studies used medical records in one fashion or another to ascertain cases of zoster and all zoster cases were drawn from a larger, well-defined, community-dwelling population. However, the methods of case ascertainment and the populations differed among studies. Hope-Simpson (1965) kept careful practice records on all patients who developed zoster over a 15 year period in the population of Cirencester, England. Ragozzino et al. (1982a) collected data on zoster from the central index data system and medical records of all of the residents of Rochester, Minnesota, US for a 15 year period.