Risk factors for symptomatic and asymptomatic norovirus infection in the community

Epidemiol Infect. 2011 Nov;139(11):1676-86. doi: 10.1017/S0950268810002839. Epub 2010 Dec 17.


The objective of this study was to investigate risk factors for norovirus-associated infectious intestinal disease (IID) and asymptomatic norovirus infection. Individuals with IID and healthy controls were recruited in a community-based study in England (1993-1996). This is the first risk-factor study to use viral load measurements, generated by real-time RT-PCR, to identify cases of norovirus-associated IID and asymptomatic infections. Using multivariable logistic regression the main risk factor identified for norovirus-associated IID was contact with a person with IID symptoms. Infectious contacts accounted for 54% of norovirus cases in young children and 39% of norovirus cases in older children and adults. For young children, contacts outside the household presented the highest risk; for older children and adults, the highest risk was associated with child contacts inside the household. Foreign travel and consumption of shellfish increased the risk of norovirus-associated IID. Lifestyle and dietary factors were associated with a decreased risk of both norovirus-associated IID and asymptomatic infection. No risk factors were identified for asymptomatic norovirus infection.

MeSH terms

  • Adolescent
  • Adult
  • Asymptomatic Infections / epidemiology*
  • Caliciviridae Infections / epidemiology*
  • Caliciviridae Infections / virology
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Community-Acquired Infections / epidemiology*
  • Community-Acquired Infections / virology
  • England / epidemiology
  • Family Characteristics
  • Feeding Behavior
  • Gastroenteritis / epidemiology*
  • Gastroenteritis / virology
  • Humans
  • Infant
  • Multivariate Analysis
  • Norovirus / isolation & purification*
  • Risk Factors
  • Travel