Genotypic analysis of varicella-zoster virus and its seroprevalence in Finland

We evaluated the seroprevalence of varicella-zoster virus (VZV) in the Finnish population among various age groups and genetically characterized VZV strains from documented cases of varicella and zoster. VZV-specific immunoglobulin G was measured in 2,842 serum samples that had been submitted for virological studies to the Department of Virology, University of Helsinki, from 1995 to 1996. Specimens for VZV genotyping were obtained from vesicular lesions from two pediatric patients and 26 adult patients. Seroprevalence to VZV varied markedly by age: 45% in children aged < or = 2 months, 12.5% in children aged 6 to 8 months, and > 90% in children near 10 years of age, plateauing thereafter into advanced age. The seroprevalence rates indicate that in Finland, as in other countries with temperate climates, primary VZV infection usually occurs during the first decade of life. Twenty-eight VZV DNA-positive specimens were analyzed to identify VZV vaccine and wild-type genotypes. All analyzed specimens were wild type and the European (E) genotype.