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Serological surveys for diphtheria were conducted in six European countries including Czech Republic, Hungary, Ireland, Latvia, Luxembourg, Slovakia and one country outside Europe, Israel. For each country, a nationally representative population sample was collected across the entire age range and was tested for antibodies to diphtheria toxin. Although each national laboratory used its preferred assay, the results were all standardized to those of the in vitro neutralization test and expressed in international units (IU) which allowed comparative analyses to be performed. The results showed that increasing age is related to a gradual increase in seronegative subjects (<0·01 IU/ml of diphtheria antitoxin antibodies). This may reflect waning immunity following childhood vaccination without repeated booster vaccinations in adults. Differences in seronegativity were also found according to gender. In subjects aged 1-19 years, geometric mean titres of antitoxin are clearly related to the different vaccination schedules used in the participating countries. Although clinical disease remains rare, the susceptibility to diphtheria observed in these serosurveys highlights the importance of strengthened surveillance.

This study was undertaken to estimate the magnitude of Bordetella pertussis infections in a highly vaccinated population in Israel in order to evaluate the relationship between clinical notification data and serology-based evidence of infection. A cross-sectional survey was conducted on a total of 1982 serum samples from the National Serum Bank, collected from January 2000 through December 2001, in order to monitor high levels of pertussis toxin (PT) IgG antibody indicative of recent B. pertussis infection, by standardized methods. The estimation yielded an infection incidence rate of 2448 per 100,000 population (> or =3 years of age) for the year 2000 compared to an annual incidence of reported pertussis of 5.6 per 100,000 for the same period. The peaks of estimated incidence of infection were found in the groups of 15-19-year olds (5245 per 100,000) and older than 60 years (6469 per 100,000), whereas the majority of clinical pertussis cases were reported for the 10-14-year olds (20.5 per 100,000). The findings clearly show that despite a high vaccination coverage rate (>93%), there is still a considerable circulation of B. pertussis, particularly in adolescents and elderly. Population-based serosurveillance for pertussis offers the potential to assist interpretation of trends independent of notification and diagnostic bias., (Copyright 2010 Elsevier Ltd. All rights reserved.)