Data quality of 5 years of central norovirus outbreak reporting in the European Network for food-borne viruses

ABSTRACT Background The food-borne viruses in Europe (FBVE) network database was established in 1999 to monitor trends in outbreaks of gastroenteritisdue to noroviruses (NoVs), to identify major transmission routes of NoV infections within and between participating countries and to detectdiffuse international food-borne outbreaks.Methods We reviewed the total of 9430 NoVoutbreak reports from 13 countries with date of onset between 1 January 2002 and 1 January2007 for representativeness, completeness and timeliness against these objectives.Results Rates of reporting ranged from a yearly average of 1.8 in 2003 to 11.6 in 2006. Completeness of reporting of an agreed minimumdataset improved over the years, both for epidemiological and virological data. For the 10 countries that provided integrated (epidemiological ANDvirological) reporting over the 5-year period, the completeness of the minimum dataset rose from 15% in 2003 to 48% in 2006. Two countrieshave not been able to combine both data types due to the structure of the national surveillance system (England and Wales and Germany).Timeliness of reporting (median days between the onset of an outbreak and the date of reporting to the FBVE database) differed greatly betweencountries, but gradually improved to 47 days in 2006.Conclusion The outbreaks reported to the FBVE reflect the lack of standardization of surveillance systems across Europe, making directcomparison of data between countries difficult. However, trends in reported outbreaks per country, distribution of NoV genotypes, and detectionof diffuse international outbreaks were used as background data in acute questions about NoV illness and the changing genotype distributionduring the 5-year period, shown to be of added value. Integrated reporting is essential for these objectives, but could be limited to sentinelcountries with surveillance systems that allow this integration. For successful intervention in case of diffuse international outbreaks, completenessand timeliness of reporting would need to be improved and expanded to countries that presently do not participate.Keywords Epidemiology, Food safety, Public health