Health chiefs were this week continuing their call for people to stay away from East Surrey Hospital, Redhill, unless absolutely necessary because of a wave of cases of winter vomiting disease.

The hospital, run by the Surrey and Sussex Healthcare NHS Trust, said it was still dealing with cases of patients ill with the bug, also known as norovirus.

Last week, the hospital said it was dealing with “high numbers” of patients struck down by the highly infectious bug, which is not life-threatening but involves sudden projectile vomiting and diarrhoea.

This week, a spokesman for the trust said there had been relatively little change.

He said: “We are still unable to give you exact figures for the number of people affected, but numbers have been reducing.

“Basically, it's diminishing, but it's still not completely gone away and I don't think it's likely to in the next few days and weeks.”

He said: “We still have some beds closed on a few wards.

“This means that there are patients in the beds who are being treated, but they will not be given to new patients.”

He said: “The norovirus outbreak is being resolved slowly and the number of cases is going down. “However, we would continue to say that, in all cases of suspected norovirus, East Surrey Hospital follows strict infection prevention and control guidelines, which include closing areas with suspected cases to prevent onward spread, following strict hygiene practices, discouraging non-essential visiting, and implementing enhanced cleaning and disinfection.”

He added: “We would remind Surrey and Sussex residents who have had vomiting and diarrhoea that they should not visit friends or relatives in hospital, or in a care home, until 48 hours after their symptoms have stopped.”

Norovirus is the most common cause of infectious gastroenteritis - diarrhoea and vomiting - in England and Wales.

Though sudden and involving projectile vomiting, the illness is generally mild and people usually recover fully within two to three days.

There are no long-term effects from being infected but infections can occur at any age because immunity is not long lasting.

April is somewhat later than usual for the bug to be so active, but it is not unusual, and the recent dry and mild weather may have played a part.

In December 2008 and January 2009, norovirus hit the hospital with 50 people falling ill in the first wave.

Two wards were shut to incoming patients.

In a resurgence about two weeks later, 18 more patients fell ill in four days.

In January 2010, the bug struck again at East Surrey, with 34 people spread across six wards falling ill at its peak.

A message on the hospital trust's website this week warned people to steer clear of the hospital if they felt unwell and suspected they had the bug, or had been ill in the previous week, and said they should call their GP if they suspected they had the virus.

Visiting hours at the hospital remain unchanged.