Relatives of patients in St Vincent's Hospital, Dublin, have been asked only to visit in emergencies after the number of winter-vomiting cases there rose to 160 today.
The hospital said about 95 patients and 65 staff had been diagnosed with the virus. The number of staff with the virus is up 50 per cent on yesterday.
More than 40 other patients are also showing symptoms and because the cases are widely spread, 14 wards are closed to new admissions. As a result, the hospital has warned that its accident and emergency unit is under pressure and delays are likely.
According to the hospital, the virus is in the community and children in particular are asked to refrain from hospital visits.
Elsewhere, Beaumont Hospital in Dublin has reported a small number of cases and the virus is also in Hospitals in Limerick, Kilkenny, Galway and Carlow.
The University College Hospital in Galway closed one ward after four patients showed symptoms. Two patients are also displaying symptoms at the Western Regional Hospital in Limerick.
The only other cases have been reported at St Columba's Hospital in Thomastown where five people have been diagnosed and one other case has been reported at the Sacred Heart Hospital in Carlow.
Responding to the virus outbreak, Fine Gael MEP Mr Gay Mitchell said a US-style surgeon general is needed to reform service to be a powerful "advocate for the public interest over vested interest".
