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Volume 9, Number 1—January 2003

Research

Two Epidemiologic Patterns of Norovirus Outbreaks: Surveillance in England and Wales, 1992–2000

Ben Lopman*Comments to Author , Goutam K Adak*, Mark Reacher*, and David W.G. Brown*
Author affiliations: *Public Health Laboratory Service, London, United Kingdom

Main Article

Table 3

Outbreak characteristics compared by setting of outbreak, England and Wales, 1992–2000

Setting Median
(days) N Geometric mean of duration (days)(95% CI)a t test p value
Duration of outbreaks
Hospital
 8
 679
 8.8 (8.4 to 9.3)
Residential facilities
 9
 664
 8.7 (8.1 to 9.4)
 –0.321
 0.73
School
 8
 63
 8.1 (6.8 to 9.7)
 –0.879
 0.40
Food outlet
 3
 94
 3.3 (2.8 to 3.8)
 –12.699
 <0.0001
Hotel
 5
 133
 4.3 (3.6 to 5.1)
 –7.025
 <0.0001
Other
 4
 69
 4.3 (3.6 to 5.1)
 –8.043
 <0.0001
All settings
 8
 1,702
 7.7 (7.5 to 8.0)
Numbers affected per outbreak
Hospital
 17
 751
 17.5 (16.4 to 18.5)
Residential facilities
 23
 723
 21.5 (19.8 to 23.3)
 4.895
 <0.0001
School
 24
 73
 24.9 (20.5 to 30.3)
 3.594
 <0.0001
Food outlet
 23
 104
 23.4 (19.8 to 27.6)
 3.444
 0.001
Hotel
 29
 147
 26.5 (23.0 to 30.6)
 5.729
 <0.0001
Other
 29
 74
 24.5 (20.2 to 29.7)
 3.432
 0.001
All settings 21 1,872 20.3 (19.7 to 21.1)

aCI, confidence interval.

Main Article

Appendix: Surveillance and analysis definitions

Outbreak: an incident in which two or more people, thought to have a common exposure, experience a similar illness or proven infection, at least one of them being ill (22).
General outbreak: an outbreak that affects members of more than one household, or residents of an institution (36).
General outbreak of Norovirus: a general outbreak in which Norovirus is determined to be the causative agent by electron microscopy, RT-PCR, or enzyme immunoassay in one or more affected persons.
Residential facilities: includes residential homes, which provide some assistance in day-to-day living, and nursing homes, which provide care for persons whose infirmity or illness requires nursing care on a regular basis.
Food outlets: commercial food retailers including restaurants, pubs, bars, cafeterias, mobile food vendors, and caterers.

Page created: December 07, 2010
Page updated: December 07, 2010
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The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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