Chickenpox hospitalizations among residents of Olmsted County, Minnesota, 1962 through 1981. A population-based study.

Age-specific incidence rates were determined for hospitalizations resulting from complications of chickenpox. We reviewed medical records for all Olmsted County, Minnesota, residents hospitalized for chickenpox during the 20-year period 1962 through 1981. Incidence rates based on these 25 cases showed good agreement with national rates computed from information compiled by the Commission on Professional and Hospital Activities for 669 statistically selected patients, representing about 5% of US varicella hospitalizations from January 1979 through June 1982 (about 4,000 hospitalizations annually). The most common complications were bacterial superinfections in children younger than 5 years old, varicella encephalitis (mainly acute cerebellar ataxia) and dehydration in 5- to 9-year-olds, and varicella pneumonia in adults. The high prevalence of chickenpox and its association with infectious and neurologic complications make it a continuing source of morbidity.