Decreasing risk of hepatitis A infection in León, Nicaragua: evidence from cross-sectional and longitudinal seroepidemiology studies.

Autor: Mayorga Perez O; Department of Microbiology and Parasitology, Faculty of Medical Sciences, National Autonomous University, León, Nicaragua., Brinkhof MW; Institute of Social & Preventive Medicine (ISPM), University of Berne, Berne, Switzerland., Egger M; Institute of Social & Preventive Medicine (ISPM), University of Berne, Berne, Switzerland., Frösner G; Max von Pettenkofer Institute, Ludwig-Maximilians University, Munich, Germany., Herzog C; Crucell Switzerland AG, Berne, Switzerland., Zwahlen M; Institute of Social & Preventive Medicine (ISPM), University of Berne, Berne, Switzerland.
Jazyk: angličtina
Zdroj: PloS one [PLoS One] 2014 Feb 11; Vol. 9 (2), pp. e87643. Date of Electronic Publication: 2014 Feb 11 (Print Publication: 2014).
DOI: 10.1371/journal.pone.0087643
Abstrakt: 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 León, 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 León, 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.
Databáze: MEDLINE
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