Seroprevalence of varicella-zoster virus antibody in Thailand

Abstract

Objective: To determine the seroprevalence of varicella-zoster virus antibodies in a wide age range of healthy subjects in Thailand. Design and Methods: In 1994, blood samples were collected from 559 volunteers aged 4 months to 77 years from the Bangkok area; questionnaires about socioeconomic background and history of chickenpox or herpes zoster were also completed. Serum samples were assayed for specific varicella-zoster virus (VZV) IgG antibodies using a commercial enzyme-linked immunosorbent assay kit. Results: The seroprevalence rate (61.4% overall) increased with age: less than 1 year, 10.2%; 1 to 4 years, 24.1%; 5 to 9 years, 62.5%; 10 to 14 years, 70.4%; 15 to 19 years, 78.9%; 20 to 29 years, 69.2%; 30 to 39 years, 96.1%; 40 to 49 years, 100%; and 50 years and older, 98.0%. No significant differences in the VZV antibody prevalence with respect to gender, family size, or family income were seen. There was good correlation between varicella history and seropositivity: 92.9% of subjects with a varicella history were seropositive. Conclusions: In this urban population, approximately one in three adolescents and young adults lacked natural immunity against varicella. The results suggest that vaccination programs in Thailand and probably other tropical countries should include susceptible adolescents and adults who are at high risk of developing severe varicella and resultant complications.