Two male and two female patients, confined to two wards, have been struck down by the highly infectious norovirus.

Hospital bosses also said there were 16 patients who are suspected of having viral diarrhoea and vomiting, five of whom have recently developed symptoms.

Nine male and eight female beds are out of use. However, no wards have been closed, although sanctions remain in five bays of 30 beds.

Les Boobis, director of infection prevention and control, said the hospital had taken steps to counter the bug. In addition to the hospital's normal infection control measures, the number of patients displaying symptoms are being monitored daily and confirmed cases are not being discharged to care homes or other communal-living situations.

Patients are also been asked not to leave the ward when symptomatic, and notices alerting visitors are being displayed on wards.

New patients are also not being admitted to wards where confirmed cases of the norovirus are cared for.

Mr Boobis told the Echo: "It's very important that people who have had the virus, or been in contact with someone who has had it, take precautions to avoid spreading it.

"People should also avoid visiting places like hospitals and residential homes if they have had the bug or been in contact with it over the past two days.

"Alcohol gel is effective against bacteria but not all viruses. Therefore, we are recommending that, as a matter of routine, all visitors should also wash their hands with hot water and soap when visiting our wards, and we would be very grateful if visitors could follow that guidance."

The norovirus is a stomach bug which causes nausea and diarrhoea. The spread of infection is easiest in places where groups of people are in close proximity for a time such as residential homes, schools, hospitals and workplaces.

It lasts around two days and no treatment is required. However, people may still carry the virus and infect others up to three days after their own symptoms have stopped.