EDINBURGH'S two biggest hospitals have had to close wards in the last week because of the winter vomiting bug.
The norovirus, which caused huge problems for health chiefs last winter, struck at both the city's Royal Infirmary and Western General.
The outbreak affected 25 patients and seven members of staff, the most in Scotland so far this year.
They all presented symptoms of the bug, but health chiefs, who instantly closed the wards and ordered deep cleans, said not all were confirmed. Both wards have since reopened.
It has prompted warnings from both NHS Lothian and the organisation tasked with protecting the nation's health.
Health Protection Scotland even went as far to tell people with friends or relatives in hospital not to visit them if they had been unwell for fear of passing on the potentially fatal virus.
Last year there were 723 cases, resulting in 115 ward closures, a massive rise on previous years. Now health bosses are getting ready for another round of closures, with more severe and sustained poor weather on the way.
A spokesman for HPS said an alert had been issued in England, where cases had surged from the previous month.
He added: "While that pattern has not emerged in Scotland to date and norovirus reports remain at a relatively low level, this is a potentially fast-changing situation and calls for continuing vigilance.
"Don't visit a patient in hospital if you are feeling unwell or have an infection such as flu or a cold, or if you or a member of your household is suffering from diarrhoea or vomiting.
"If you have vomiting or diarrhoea you should not visit a patient in hospital until 48 hours after your symptoms have stopped."
The country's chief medical officer, in his advice, added that handwashing was essential, a message that was also applied to stopping the spread of superbugs such as MRSA and the swine flu infection.
For most, the bug is a short-lived illness, but for those with underlying health problems it can be lethal.
Rona Broom, head of infection control at NHS Lothian, said: "Norovirus, or winter vomiting virus as it is also known, is extremely common at this time of year.
"Last week 25 patients and seven members of staff at the Royal Infirmary of Edinburgh and the Western General Hospital were symptomatic, although not all of these cases were confirmed as norovirus.
"Strict infection control procedures were put in place in both affected areas and deep cleaning has been carried out."