Victims of a winter sickness bug have been warned to stay at home to prevent its spread after a rise in cases in Leeds.
Public health experts say there has been an increase in the number of suspected norovirus cases, a bug which causes diarrhoea and vomiting.
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The virus is the most common cause of infectious gastroenteritis in England and Wales, and is especially prevalent during the winter
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Nationally, since the beginning of November the Health Protection Agency (HPA) has recorded 43 outbreaks of norovirus in hospitals.
Of those, 39 instances have led to ward closures – a rise of almost 50 per cent when compared to October.
There have been a small number of isolated cases at Wharfedale Hospital in Otley, though in Leeds the two main hospitals – Leeds General Infirmary and St James's – have so far been unaffected.
Now health bosses have warned anyone with symptoms of the illness to stay at home to avoid spreading it to the vulnerable.
Dr Mike Gent, interim unit director at the West Yorkshire Health Protection Unit, said: "We realise that people will be planning to visit friends and relatives in hospitals, care or nursing homes this Christmas, but people here are particularly vulnerable to infection.
"If you've had symptoms of diarrhoea and vomiting in the last two days, the best thing you can do to protect your loved ones is to delay any visits to these places until fully recovered."
He added that good hygiene, in particular washing hands after visiting the toilet, was essential for anyone affected and they should also stay off work or school until they have been without symptoms for 48 hours.
Ruth Holt, chief nurse and director of infection prevention at Leeds Teaching Hospitals NHS Trust, added: "We know how quickly infections like norovirus can spread in a confined space like a hospital ward so it is extremely important the public help us keep our patients as safe as possible.
"We have procedures in place to control the spread of infections in our wards when they do occur, but the best protection of all is to prevent the illness coming into hospital in the first place."
Dr Simon Balmer, public health consultant at NHS Leeds, said: "There is no specific treatment for the virus, apart from letting the illness run its course and so, in the majority of cases, there is no benefit to visiting a GP or A&E."