A VICIOUS strain of food poisoning has forced the closure of seven day centres that look after people with learning disabilities.

The bug, which swept through the Ridgeway Centre in Weymouth, is believed by health officials to be the Norwalk virus, which causes vomiting and diarrhoea.

Environmental health chiefs ordered the centre to be closed after 23 service users and three staff members were struck down. Six satellite sites - the Southill Centre, Crossroads, The Rowans, The Oaks and two units on Mount Pleasant - have also been shut until Monday to isolate the virus, which is airborne and can be caught from food.

Staff at Derriford Hospital in Plymouth closed wards and cancelled operations and Yeovil District Hospital confirmed 65 patients had fallen ill after the bug, previously known as the winter vomiting virus, took hold.

Dorset County Council's provider of services manager, Nigel Coles, said: "We have had an outbreak of diarrhoea and vomiting at the Ridgeway Centre in Weymouth.

"We are looking at the Norwalk virus as a possible cause because it has been so virulent in some hospitals and establishments recently.

"The environmental health department is continuing investigations into the case of the outbreak and instructed us to isolate the unit for at least two days, but our residential homes are still open." Weymouth and Portland Borough Council's environmental health manager, Tony Beeson, said: "The symptoms spread very quickly, so we had to act promptly and we hope it is under control now. The numbers are relatively small compared with the potential problem we could have had and we are working very closely with other agencies.

"It will not be an epidemic on the scale being experienced elsewhere in the westcountry."

Dorset's consultant in health protection, Dr Sue Bennett, said: "There is quite a lot of it about in Dorset at the moment and we are advising people who contract the symptoms to stay away from others and drink plenty of clear fluids."

Service users have voiced concerns about the centres getting the all-clear so quickly.

One mum whose son attends the Ridgeway Centre, who asked not to be named, said: "How do we know the centres will be clear of the bug by Monday? It could have been brewing for a while, why was nothing done to prevent this earlier?"

WHAT IS IT?

THE Norwalk virus was named after a school in Norwalk, Ohio, where it was first recorded.

Symptoms include nausea, vomiting, diarrhoea, abdominal pain, headache and some fever.

A few patients will become severely dehydrated and require intravenous fluids.

The infection develops 24 to 48 hours after contaminated food or water is taken and lasts between one and three days.

Water, shellfish and salad ingredients are the most common source of outbreaks, but humans can also become contaminated from an infected food preparer.

The family of Norwalk-like viruses may be spread from person-to-person and through vomit or stools. Adults and older children are more likely to be affected and sufferers can become temporarily immune to the disease.