Dozens of hospital wards all over England are being closed to new admissions in order to control a highly infectious winter vomiting disease.

The closures offer the quickest way of controlling the outbreak of norovirus infections, which although seasonal, has started sooner than usual and could involve more cases than in previous years.

The virus causes a short-lived infection with symptoms such as vomiting, diarrhoea, and fever and can spread quickly, costing the NHS more than £100 million a year.

The infective dose is very small, so anybody looking after a sufferer is in danger of catching the illness. Scrupulous hygiene – including the use of gloves for cleaning toilets, for example – is vital.

Many hospitals are appealing to anybody suffering from vomiting or diarrhoea symptoms not to visit while they are unwell, to come in unnecessarily, or to bring in small children.

At Torquay Hospital, for example, which has been affected “on and off” by the virus since early November, a spokesman said: “We are still appealing to people to think twice about visiting or coming into A&E if they have the symptoms.”

Cruise ships, which often suffer norovirus outbreaks, have found it extremely difficult to eliminate. The NHS policy of closing wards to new admissions may seem extreme, but is effective.

“Taking action early in an outbreak by closing a ward to new admissions can help control outbreaks” an Health Protection Agency (HPA) spokeswoman said.

“A study by the HPA has shown that outbreaks of norovirus are shortened when control measures at healthcare settings are implemented quickly, such as closing wards to new admissions within four days of the beginning of the outbreak and implementing strict hygiene measures.”

Estimates of actual numbers of infections are largely guesswork, since most people treat themselves at home and do not even consult a doctor.

The only hard data are the confirmed laboratory reports from the HPA, which represent only a tiny fraction of total cases. This year up to the end of November there had been 1,325 confirmed cases, the highest since the equivalent period of 2002, when there were 1,845.

But only one case in about 1,500 is ever confirmed by lab tests, and this year a more sensitive test has been introduced by the HPA’s regional laboratories. So it is possible that the rise is simply an artefact of the new testing method.

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