The diarrhoea and vomiting bug norovirus has spread to five hospitals across north Wales, with 31 patients falling ill, a health board says.
Visitors are being urged to help stop the infection at Ysbyty Gwynedd, along with Dolgellau, Colwyn Bay, Glan Clwyd and Wrexham Maelor hospitals.
Betsi Cadwaladr University Health Board says there are restrictions on admissions at eight wards.
The number of norovirus infections in the UK is at higher levels than normal.
BBC News
Fifty guests at a diamond wedding party in Wolverhampton were struck down with Norovirus prompting a city-wide alert to GPs.
The outbreak of the bug occurred after the anniversary party in Tettenhall. Everyone is understood to have now recovered but guests had to answer questions from doctors and the Health Protection Agency.
Wolverhampton City Council said tests of food samples indicated it was a viral infection and nothing to do with the venue itself or caterers.
The Health Protection Agency (HPA), Wolverhampton City Primary Care Trust and the council worked together to establish the cause of the 50 cases of diarrhoea and vomiting and confirmed it was Norovirus.
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