Beaumont hospital has issued an urgent appeal to the public to refrain from visiting this bank holiday weekend unless absolutely necessary.
Fifteen new cases of norovirus, also known as the winter vomiting virus, were detected at the hospital today.
The latest cases bring to 52 the number of patients displaying the symptoms of the bug.
The outbreak spread rapidly and continues to affect the majority of wards, the hospital has said and a total of 19 beds are currently closed in the wards affected.
Only visits which are "absolutely essential" are allowed to any ward and, even then, are restricted to one visitor per patient. No children are allowed to visit under any circumstances.
Visiting restrictions were introduced following the start of the outbreak a week ago.
Norovirus usually lasts 24 to 48 hours and does not usually require medical treatment. Symptoms of the virus include abdominal cramps, vomiting and diarrhoea.
Members of the public who have symptoms are advised to contact their GP in the first instance if they have serious concerns.
