Shifting susceptibility to hepatitis A among children and adolescents over the past decade [Mudança na suscetibilidade à hepatite A em crianças e adolescentes na última década]

Objectives: to estimate the prevalence of anti-hepatitis a virus (anti-hav) antibodies in serum samples from children and adolescents obtained at two clinical pathology laboratories in the city of porto alegre,south of brazil,and to compare findings to those of a study carried out in the 1990s. methods: in this cross-sectional study conducted between 2007 and 2008,465 serum samples obtained from subjects aged 1-19 years were consecutively tested to determine the prevalence of total anti-hav antibodies. samples were provided by a public laboratory (group 1) that serves the unified health system exclusively,meant to represent the lowest socioeconomic strata,and by a private laboratory (group 2),meant to represent the higher socioeconomic classes. tests were performed at a single laboratory using commercially available electrochemiluminescence kits. antibody levels ≥ 20 ui/l were considered positive. results: the seroprevalence of anti-hav in group 1 was 37.6%. the percentage of anti-hav reactivity increased from 19.4% in the 1-to-4 group to 54.1% in the 15-to-19 group. in group 2,overall anti-hav positivity was 46.1% and was inversely correlated with age,declining from roughly 50% in the youngest groups to 29.1% in the 15-to-19 group. comparison of sample findings to those reported in a 1990s study showed a significant reduction in anti-hav prevalence among 5-to-9-year-olds in group 1 (p = 0.03). conclusions: the results suggest that the endemicity of hepatitis a in porto alegre has been declining over the past decade,and that children and adolescents,particularly those in the lowest socioeconomic strata,are more susceptible to the disease. copyright © 2011 by sociedade brasileira de pediatria.