Validierung einer syndromischen Surveillance akuter Respirationstrakt-Erkrankungen in Kindergärten und Kindertagesstätten Schleswig-Holsteins (SHARE)

Abstract

To obtain reliable, regionalized, and timely data for the spread of seasonal influenza in various age groups, which are preferentially affected by the influenza virus, a syndromic surveillance system for acute respiratory tract infections in Schleswig-Holstein (SHARE) was established in preschools and nurseries starting in 2006. The Schleswig-Flensburg district with 12 of 114 preschools and nurseries and 850 of 5,750 supervised children served as a pilot district. The weekly rates of sickness absenteeism correlated most strongly with the onset of seasonal influenza and with population density during the first half of the year. Mean annual sickness absenteeism levels of above 6% occurred more frequently above a population density of 200 inhabitants/km(2) than below this density (relative risk 2.50, 95% confidence interval 1.18-5.32). By analysis of the receiver-operating characteristic curve, the diagnostic performance of the SHARE system as a classifier for seasonal influenza was determined. The sensitivity was 83% and the specificity was 79% when sickness absence rates exceeded 5%. The performance of the SHARE system correlated with the size of the kindergarten. In 2008, 13 of 15 districts of Schleswig-Holstein participated with 157 of 1,684 kindergarten and 10,300 of 113,000 children. The evaluation for 2008 confirmed that the SHARE system is suitable for the surveillance of seasonal influenza at the district and state levels.