text: Patients on two wards at University Hospital Llandough are suffering from the illness, which can pass quickly from person to person.
  The hospital said the spread of the virus would be limited if people made only absolutely necessary visits.
  Cardiff and Vale health board said it was asking people to be "sensible".
  Chief operating officer Alice Casey said: "Many people will have the norovirus bug at this time of year - we see it every year and, for most people, it will be unpleasant but not serious.
  "But when norovirus spreads in hospitals, where patients are already unwell and are in close proximity to each other on wards, the effects can be more serious."
  Norovirus is a highly contagious virus which causes nausea, vomiting and diarrhoea.
  The symptoms begin about 12 to 48 hours after infection and usually last for between 12 and 60 hours.
target: Visitors have been asked to stay away from a Vale of Glamorgan hospital because of an outbreak of norovirus.