An outbreak of winter vomiting bug norovirus has seen bays closed on five hospital wards in Cornwall.
People are now being urged by NHS leaders to stay at home if they feel unwell.
Four wards at the Royal Cornwall Hospital Trust have had to close bays due to norovirus cases as well as one ward at a community hospital in the county.
Director of infection prevention and control for both Royal Cornwall Hospitals NHS Trust and Cornwall Partnership NHS Foundation Trust Louise Dickinson is urging people to stay at home for 48 hours after being unwell.
She said: “We want the public to be aware that norovirus, commonly known as the winter vomiting bug, is circulating in some healthcare settings and within the community right now.
"People can play a part in helping to reduce its spread though. I urge anyone who’s picked up this virus that causes diarrhoea and vomiting, not to go back to work or school until at least 48 hours after symptoms pass."
Although norovirus is an unpleasant illness, for most people it usually passes in a couple of days.
The advice from the NHS is to treat symptoms at home, stay hydrated and prevent onward spread by washing hands regularly and cleaning surfaces in affected areas. Louise added: “Many people might not realise but the virus is often brought into hospital buildings by well-meaning visitors.
"We want people to be aware of norovirus so they don't accidently give it to loved ones they may be visiting in our hospitals. The same applies for any setting, including GP surgeries.
"Unless symptoms persist for more than a few days, it’s best to reduce contact with others, stay home, drink plenty of water and take paracetamol. If symptoms go on for longer, call 111 for advice.”