Estimating the under-reporting of norovirus illness in Germany utilizing enhanced awareness of diarrhoea during a large outbreak of Shiga toxin-producing E. coli O104:H4 in 2011 - a time series analysis
2014 (English)In: BMC Infectious Diseases, ISSN 1471-2334, Vol. 14, 116- p.Article in journal (Refereed) Published
Background: Laboratory- confirmed norovirus illness is reportable in Germany since 2001. Reported case numbers are known to be undercounts, and a valid estimate of the actual incidence in Germany does not exist. An increase of reported norovirus illness was observed simultaneously to a large outbreak of Shiga toxin-producing E. coli O104: H4 in Germany in 2011 - likely due to enhanced (but not complete) awareness of diarrhoea at that time. We aimed at estimating age- and sex-specific factors of that excess, which should be interpretable as (minimal) under-reporting factors of norovirus illness in Germany. Methods: We used national reporting data on laboratory-confirmed norovirus illness in Germany from calendar week 31 in 2003 through calendar week 30 in 2012. A negative binomial time series regression model was used to describe the weekly counts in 8.2 age- sex strata while adjusting for secular trend and seasonality. Overall as well as age- and sex- specific factors for the excess were estimated by including additional terms (either an O104: H4 outbreak period indicator or a triple interaction term between outbreak period, age and sex) in the model. Results: We estimated the overall under- reporting factor to be 1.76 (95% Cl 1.28- 2.41) for the first three weeks of the outbreak before the outbreak vehicle was publicly communicated. Highest under-reporting factors were here estimated for 20- 29 year-old males (2.88, 95% Cl 2.01- 4.11) and females (2.67, 95% Cl 1.87- 3.79). Under-reporting was substantially lower in persons aged < 10 years and 70 years or older. Conclusions: These are the first estimates of (minimal) under- reporting factors for norovirus illness in Germany. They provide a starting point for a more detailed investigation of the relationship between actual incidence and reporting incidence of norovirus illness in Germany.
Place, publisher, year, edition, pages
2014. Vol. 14, 116- p.
Norovirus, Gastroenteritis, Epidemiology, Disease notification, Time series analysis, Public health, Population surveillance, Under-reporting
Mathematics Medical and Health Sciences
IdentifiersURN: urn:nbn:se:su:diva-102777DOI: 10.1186/1471-2334-14-116ISI: 000332630600002OAI: oai:DiVA.org:su-102777DiVA: diva2:713582