title: Community incidence of norovirus-associated infectious intestinal disease in England: improved estimates using viral load for norovirus diagnosis.
abstract: Existing estimates of the incidence of infectious intestinal disease (IID) caused by norovirus are based on electron microscopy or reverse transcription-polymerase chain reaction (RT-PCR). Neither method accurately represents norovirus disease burden: Electron microscopy has poor diagnostic sensitivity, and RT-PCR has poor diagnostic specificity. In this study, viral load measurements were used to identify cases of norovirus-associated IID and to produce new incidence estimates for England. IID cases were ascertained in the Study of Infectious Intestinal Disease in England (1993-1996), and stool specimens were tested by semiquantitative real-time RT-PCR for norovirus. The age-adjusted community incidence of norovirus-associated IID was 4.5/100 person-years (95% credibility interval: 3.8, 5.2), equating to 2 million episodes/year. Among children aged less than 5 years, the community incidence was 21.4/100 person-years (95% credibility interval: 15.9, 27.7), and the incidence of consultations to general practitioners for norovirus-associated IID was 3.2/100 person-years (95% credibility interval: 2.6, 3.8), with 100,000 children visiting their general practitioner for norovirus-associated IID each year. Norovirus is the most common cause of IID in the community in England and is responsible for a similar number of pediatric primary care consultations as rotavirus.
authors.affiliation: Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom. gemma.phillips@lshtm.ac.uk
authors.forename: Gemma
authors.initials: G
authors.lastname: Phillips
authors.forename: Clarence C
authors.initials: CC
authors.lastname: Tam
authors.forename: Stefano
authors.initials: S
authors.lastname: Conti
authors.forename: Laura C
authors.initials: LC
authors.lastname: Rodrigues
authors.forename: David
authors.initials: D
authors.lastname: Brown
authors.forename: Miren
authors.initials: M
authors.lastname: Iturriza-Gomara
authors.forename: Jim
authors.initials: J
authors.lastname: Gray
authors.forename: Ben
authors.initials: B
authors.lastname: Lopman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017250:Caliciviridae Infections / Q000175:diagnosis* / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004739:England / Q000453:epidemiology; D005243:Feces / Q000821:virology; D005759:Gastroenteritis / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology*; D006801:Humans; D015994:Incidence; D007223:Infant; D008875:Middle Aged; D029322:Norovirus; D011237:Predictive Value of Tests; D019562:Viral Load; D055815:Young Adult