Prevalence and characteristics of asymptomatic norovirus infection in the community in England

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 (1993England ( -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.England; gastroenteritis; incidence; Monte Carlo method; Norovirus; primary health care; reverse transcriptase polymerase chain reaction Abbreviations: IID, infectious intestinal disease; ROC, receiver operating characteristic; RT-PCR, reverse transcription-polymerase chain reaction.

A Single-Amino-Acid Change in Murine Norovirus NS1/2 Is Sufficient for Colonic Tropism and Persistence

“…There is no clear animal reservoir for HuNoV, suggesting that it has other adaptations for viral maintenance between outbreaks. Asymptomatic and persistent shedding is likely to be one way that HuNoVs are maintained (4)(5)(6)(7)11), yet many questions remain about the mechanism of NoV persistence. Furthermore, while asymptomatic shedding has been demonstrated for many enteric viruses (43)(44)(45), a tractable model has not been established in which to study enteric persistence.…”

“…There is no evidence for an animal reservoir of HuNoV, suggesting that asymptomatic shedding within the human population initiates symptomatic infection. Indeed, PCR-based detection has shown that HuNoVs are present in asymptomatic individuals within a variety of communities and ranges in prevalence from 3 to 13% (4)(5)(6)(7). Furthermore, experimental infection of volunteers revealed that some individuals continue to shed virus for up to weeks after the resolution of symptoms (8), and there are examples where outbreaks likely originated with asymptomatic HuNoV shedders (9)(10)(11).…”

Multicenter Evaluation of the Xpert Norovirus Assay for Detection of Norovirus Genogroups I and II in Fecal Specimens

“…Real-time RT-PCR testing of fecal specimens of asymptomatic individuals in England revealed a 12% age-adjusted prevalence of norovirus, with the highest prevalence noted for children Ͻ5 years of age (27). One source of asymptomatic shedding can be a recently resolved infection.…”

Year-Round Prevalence of Norovirus in the Environment of Catering Companies without a Recently Reported Outbreak of Gastroenteritis

“…A recent paper reported that the age-adjusted prevalence of asymptomatic NoV infection in England was 12%, and it displayed winter seasonality (22). Shedding in combination with inappropriate personal hygienic measures may easily lead to contamination of surfaces or food, which also applies when hands are not properly washed after staff clean bathrooms or change diapers.…”