No abstract

Ten years after the first seroprevalence study performed in Flanders, the aim of this cross sectional study was to follow the evolution of hepatitis A, B and C prevalence. The prevalence of hepatitis A antibodies, hepatitis B surface antigen and hepatitis C antibodies was measured in oral fluid samples collected by postal survey. Using the National Population Register, an incremental sampling plan was developed to obtain a representative sampling of the general population. A total of 24,000 persons were selected and 6,000 persons among them contacted in a first wave. With 1834 participants a response rate of 30.6% was achieved. The prevalence was weighted for age and was 20.2% (95% CI 19.43-21.08) for hepatitis A, 0.66% (95% CI 0.51-0.84) for hepatitis B surface antigen and 0.12% (95% CI 0.09-0.39) for hepatitis C. The prevalence of hepatitis A and C in the Flemish population is lower in 2003 compared with the results of the study performed in 1993. The difference may be due to a real decrease of the diseases but also to differences in the methodology. The prevalence of hepatitis B surface antigen remains stable. Considering the 30% response rate and the high quality of the self-collected samples as reflect of a good participation of the general population, saliva test for prevalence study is a good epidemiological monitoring tool.

SUMMARYThe aim of the European Sero-Epidemiology Network is to establish comparability of the serological surveillance of vaccine-preventable diseases in Europe. The designated reference laboratory (RL) for measles, mumps, rubella (MMR) prepared and tested a panel of 151 sera by the reference enzyme immunoassay (rEIA). Laboratories in 21 countries tested the panel for antibodies against MMR using their usual assay (a total of 16 different EIAs) and the results were plotted against the reference results in order to obtain equations for the standardization of national serum surveys. The RL also tested the panel by the plaque neutralization test (PNT). Large differences in qualitative results were found compared to the RL. Well-fitting standardization equations with R 2 o0 . 8 were obtained for almost all laboratories through regression of the quantitative results against those of the RL. When compared to PNT, the rEIA had a sensitivity of 95 . 3%, 92 . 8% and 100 % and a specificity of 100%, 87 . 1 % and 92 . 8 % for measles, mumps and rubella, respectively. The need for standardization was highlighted by substantial inter-country differences. Standardization was successful and the selected standardization equations allowed the conversion of local serological results into common units and enabled direct comparison of seroprevalence data of the participating countries.

Susceptibility to vaccine-preventable diseases in Belgium in 2006 was estimated from a serum survey. Immunoglobulins against measles, mumps, rubella (MMR) and diphtheria at all available ages (1-65 years), and against tetanus in >40-year-olds, were measured by ELISA. Age-standardized overall seronegativity for MMR was low (3·9%, 8·0%, 10·4%, respectively). However, the World Health Organization's targets for measles elimination were not met in 5- to 24-year-olds and about 1 in 7 women at childbearing age (15-39 years) were seronegative for rubella. In adults >40 years, tetanus immunity (87·2%, >0·16 IU/ml) largely exceeded diphtheria immunity (20-45%, >0·1 IU/ml). Despite free universal vaccination against MMR for more than 20 years and against diphtheria and tetanus for almost 60 years, our study revealed specific age groups remaining at risk for infection with these pathogens.

No abstract