title: Norovirus in a Dutch tertiary care hospital (2002-2007): frequent nosocomial transmission and dominance of GIIb strains in young children.
abstract: We report a retrospective analysis of norovirus (NoV) infections occurring in patients of a tertiary care hospital during five winter seasons (2002/03 to 2006/07). Data were compared with national surveillance data and with corresponding data for rotavirus. Between July 2002 and June 2007, faecal specimens from 221 (9.0%) of 2458 hospital patients with diarrhoea tested positive for NoV. The incidence in children varied from 2.52 per 1000 admissions in 2004/05 (when testing began to be performed routinely) to 11.9 per 1000 admissions in 2006/07, while the incidence in adults remained stable (mean: 1.49 per 1000 admissions). Two genotypes predominated during the study period: GIIb strains occurred mainly in children below the age of two-and-a-half years [odds ratio (OR): 14.7; P<0.0001] whereas GII.4 strains affected all age groups. Compared with rotavirus infections, NoV infections in children were more often hospital-acquired (59% vs 39%, OR: 2.29; P<0.01). Among these cases we identified 22 clusters of NoV infection among inpatients. Twelve of 53 patients from whom follow-up samples were available demonstrated long-term virus shedding. We report a dynamic pattern of sporadic NoV infections in large hospitals, with frequent nosocomial transmission and with the predominance of GIIb-related strains in children. Effective prevention strategies are required to reduce the impact of sporadic NoV infection in vulnerable patients.
authors.affiliation: Department of Virology, Erasmus Medical Center, Rotterdam, The Netherlands. m.beersma@erasmusmc.nl
authors.forename: M F C
authors.initials: MF
authors.lastname: Beersma
authors.forename: M
authors.initials: M
authors.lastname: Schutten
authors.forename: H
authors.initials: H
authors.lastname: Vennema
authors.forename: N G
authors.initials: NG
authors.lastname: Hartwig
authors.forename: T H M
authors.initials: TH
authors.lastname: Mes
authors.forename: A D M E
authors.initials: AD
authors.lastname: Osterhaus
authors.forename: G J J
authors.initials: GJ
authors.lastname: van Doornum
authors.forename: M
authors.initials: M
authors.lastname: Koopmans
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000235:genetics / Q000635:transmission; D002648:Child; D002675:Child, Preschool; D003428:Cross Infection / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D004196:Disease Outbreaks; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology; D005838:Genotype; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D009426:Netherlands / Q000453:epidemiology; D029322:Norovirus / Q000235:genetics / Q000302:isolation & purification*; D012189:Retrospective Studies; D055815:Young Adult