The prevalence of hepatitis A in children in British Columbia.

Background: The risk of hepatitis A virus (HAV) infection during childhood is difficult to estimate without population serosurveys because HAV-related symptoms are often mild at this age. Few serosurveys have been conducted in Canada. The present study surveyed teenagers in two nonurban regions of British Columbia where the historical rate of reported HAV either exceeded (region A) or was less than (region B) the historical provincial rate.

Methods: A point prevalence survey of salivary HAV-specific immunoglobulin G was conducted in high schools among grade 9 students in regions A and B. A questionnaire was used to gather sociodemographic data. The survey was extended to grade 1 and grade 5 students in community 1 of region B. Associations between risk factors and prior infection were evaluated by logistic regression.

Results: Eight hundred eleven grade 9 students were tested. Antibody to HAV was detected in 4.7% of students in region A (95% CI 2.9% to 7.2%) and 9.6% of students in region B (95% CI 6.9% to 12.9%). The region B figure reflected HAV antibody prevalence rates of 19.5% in community 1 and 2.5% in the remainder of the region. Younger students in community 1 had low HAV antibody to HAV prevalence rates (3.9% for grade 1 and 3.1% for grade 5), and positive tests in this community were associated with a particular school, foreign travel and brief residence. The risk factors for HAV infection in grade 9 students were not determined.

Conclusions: Children in nonurban areas of British Columbia are generally at low risk of HAV infection during the first decade of life regardless of the reported population rates, thereby permitting the consideration of school-based HAV immunization programs.