The North Western Health Board has confirmed there are 12 cases of the Winter Vomiting Bug in Sligo General Hospital. Lab results are awaited on a further eight suspected cases.
Elective surgery has been cancelled in the hospital until tomorrow, at least, in order to ease the pressure on the hospital. This will be reviewed tomorrow.
The board has asked people who have had symptoms of diarrhoea and vomiting over the past 72 hours not to come to the hospital, either as a visitor or as an out-patient.
In Dublin's Beaumont Hospital a dozen patients have been tested for the bug after presenting with symptoms consistent with the virus. All of the patients are within the same ward.
A spokesperson for the hospital said no more admissions will be made to the ward until lab results are known early tomorrow.
Visitors are not being restricted at present, however the hospital is issuing them with information leaflets and is advising them to wash their hands before entering the ward.
An outbreak of the virus at Beaumont last year forced it to cancel all elective surgery and cancel admissions.