title: Etiological role of viruses in outbreaks of acute gastroenteritis in The Netherlands from 1994 through 2005.
abstract: Acute gastroenteritis is one of the most common diseases worldwide. In developed countries, viruses, particularly noroviruses, are recognized as the leading cause. In The Netherlands, the surveillance of gastroenteritis outbreaks with suspected viral etiologies (as determined by Kaplan criteria) was established by the National Institute for Public Health and the Environment in 1994. This paper presents an overview of viral gastroenteritis outbreaks reported from 1994 through 2005. A minimum epidemiological data set consisting of the associated setting(s), the probable transmission mode, the date of the first illness and the date of sampling, the number of persons affected, and the number of hospitalizations was requested for each reported outbreak. Stool samples were tested for the presence of norovirus, sapovirus, rotavirus, astrovirus, adenovirus, and Aichi virus by electron microscopy, enzyme-linked immunosorbent assay, and/or reverse transcription-PCR. A total of 6,707 stool samples from 941 gastroenteritis outbreaks were investigated. Noroviruses were detected as the causative agent in 735 (78.1%) of the outbreaks, and rotaviruses, adenoviruses, and astroviruses were found to be responsible for 46 (4.9%), 9 (1.0%), and 5 (0.5%) outbreaks, respectively. Among the gastroenteritis outbreaks in which a mode of transmission was identified, most outbreaks (38.1%) were associated with person-to-person transmission, and the majority (54.9%) of the outbreaks investigated were reported by residential institutions. Since 2002, the total number of outbreaks reported and the number of unexplained outbreaks have increased. Furthermore, the number of rotavirus-associated outbreaks has increased, especially in nursing homes. Despite thorough testing, 115 (12.2%) outbreaks suspected of having viral etiologies remain unexplained. Increases in numbers of reported outbreaks may indicate undefined changes in the criteria for reporting or the emergence of new pathogens.
authors.affiliation: National Institute for Public Health and the Environment, Center for Infectious Disease Control, P.O. Box 1, 3720 BA Bilthoven, The Netherlands. Sanela.Svraka@RIVM.NL
authors.forename: Sanela
authors.initials: S
authors.lastname: Svraka
authors.forename: Erwin
authors.initials: E
authors.lastname: Duizer
authors.forename: Harry
authors.initials: H
authors.lastname: Vennema
authors.forename: Erwin
authors.initials: E
authors.lastname: de Bruin
authors.forename: Bas
authors.initials: B
authors.lastname: van der Veer
authors.forename: Bram
authors.initials: B
authors.lastname: Dorresteijn
authors.forename: Marion
authors.initials: M
authors.lastname: Koopmans
mesh_terms: D004196:Disease Outbreaks; D005243:Feces / Q000821:virology; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology*; D006801:Humans; D009426:Netherlands / Q000453:epidemiology; D011159:Population Surveillance; D012621:Seasons; D013997:Time Factors; D014777:Virus Diseases / Q000453:epidemiology*