People visiting patients at Falmouth Community Hospital are being warned to stay away if they have recently been ill because of fears that they could take in the highly contagious "vomiting bug" Norwalk.

Staff at the hospital fear that infestation of the bug, which is "extremely contagious", could lead to major disruption to care with the possibility of patients having to stay in longer than necessary, forced absences of staff and even operations being delayed.

Spokesman for the Central Cornwall Primary Health Care Trust Louise Williams said: "Falmouth Hospital does not have any problem with the virus at present but we are very keen to keep it that way. We are warning any people who have had symptoms of vomiting or diarrhoea, or who has recently seen anyone that has, to stay away from the hospital.

"The hospital has had the virus in the past, and in those instances it has had no choice but to let it run its course. At those times the hospital has had to limit patient visits and keep staff off work until the period of infection has passed," she said.

Symptoms of the virus include severe vomiting and diarrhoea, often with stomach and muscle pain, headaches, chills and fevers. The bug is also a common cause of gastro-enteritis.

The virus is air-borne and can be transferred easily through touch or food. Once struck, patients remain infectious up to 48 hours after the symptoms have past.

Those who are already sick, together with elderly people who make up a large proportion of patients at Falmouth Hospital, are particularly vulnerable to prolonged infection from the bug, according to Laura Mason, spokesman for Royal Cornwall Hospitals Trust.

"This virus spreads very quickly in places where people are enclosed together in one place. Older people and the sick tend to suffer even more acutely than the healthy," she said, warning that other institutions such as residential homes could be equally at risk - especially at Christmas.

"The festive season is a time when lots of people travel to see relatives, whilst at the same time going to parties and socialising - all these things can increase risk of infection," she said.

The Norwalk or "winter vomiting bug" recently hit the headlines when hundreds of passengers from the Aurora cruise ship were struck down.

The campaign at Falmouth Hospital comes as part of a countywide drive to try to reduce the "huge numbers of bed days that could be lost this winter if the virus gets into our hospitals," said Dr Jim O'Brian, director of public health for the South West.

"Having to close a school or stop passengers disembarking from a cruise liner is bad enough but when Norwalk is let loose in a hospital the consequences can be even more dramatic," he said.

"There is a common conception that the virus is a hospital-acquired infection. In the majority of cases it isn't. It lives in the community and that is why we need to make people aware of the risks."

Falmouth Hospital is now running a poster campaign and will be trying to talk to visitors who have recently been sick to gauge whether their presence at the hospital is "appropriate".