%0 Journal Article
%T Decreasing Risk of Hepatitis A Infection in Le¨®n, Nicaragua: Evidence from Cross-Sectional and Longitudinal Seroepidemiology Studies
%A Orlando Mayorga Perez
%A Martin W. G. Brinkhof
%A Matthias Egger
%A Gert Fr£¿sner
%A Christian Herzog
%A Marcel Zwahlen
%J PLOS ONE
%D 2014
%I Public Library of Science (PLoS)
%R 10.1371/journal.pone.0087643
%X Background and Objectives Nicaragua is highly endemic for hepatitis A. We aimed to provide an estimate of the change in the age-specific risk of hepatitis A virus (HAV) infection based on serological data from cross-sectional and longitudinal samples collected in Le¨®n, Nicaragua, in 1995/96 (n = 979) and 2003 (n = 494). Methods The observed age-specific prevalence of anti-HAV antibodies was correlated to the age-specific risk of infection by calculating the probability of freedom from infection at a specific age. Results The proportion of seropositive children aged 1.5 to 6 years was 42% in 2003 compared to 67% in 1995/96. Estimated annual risk of infection for a 3-year old child was 30% (95% CI: 27.0%, 33.1%) in 1995 and 15.5% (95% CI: 12.4%, 19.0%) in 2003. There was good agreement between estimates based on cross-sectional and longitudinal data. The age-specific geometric mean of the quantified anti-HAV antibody levels assessed in 2003 was highest at age 4 and decreased steadily up to age 40. Conclusions The substantially lower risk of HAV infection in 2003 than in 1995 for young children indicates a beginning transition from high to intermediate endemicity in Le¨®n, Nicaragua. Consecutive age-stratified serosurveys are useful to assess changes in risk of infection following public health interventions. The decreasing age-specific GMC of anti-HAV antibodies during adulthood in a country with endemic HAV indirectly suggests that ongoing HAV exposure in the community has marginal boosting effect on antibody levels once protective immunity has been established by natural infection.
%U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0087643