Robert Pigott reports: "Further cases are likely"

A week after the first victims were admitted, experts remain uncertain about whether the full extent of infection has been uncovered.

As the incubation period for E.coli lasts a fortnight, doctors cannot be sure the worst has now passed. Another 11 people are awaiting test results.

Sufferers with fewer symptoms are also believed to have received treatment from their GPs.

Three children, one an 18-month-old girl, are continuing to receive treatment for kidney problems. Doctors say they remain hopeful all will make a complete recovery.

Most of the victims are children from the Cockermouth area, but some are pensioners in their 70s.

Environmental health officers are confident they have contained the source of the infection after shutting down a pasteurisation unit at a farm in Brigham, Cockermouth, which supplied milk in the area.

Health officials are urging people to take extra care about hygiene to prevent the spread of the infection.

Stella Goh: "We have traced the source of the infection"

The harmful E.coli 0157 strain is found mainly in the gut of cattle.

An outbreak killed 21 people in central Scotland in 1996 and 1997.

The number of cases in the UK has tripled over the last decade.

Dr Stella Goh, of North Cumbria Health Authority, said officials had been informed of several cases of E.coli 0157 poisoning on 2 March.

Dr Stella Goh has warned GPs to be vigilant

A prohibition order was issued to stop the farmer distributing and supplying milk the following day.

She urged people who had bought milk from the supplier, William Thompson, before and up to 3 March to throw it away.

She said: "We are taking this infection very seriously. Obviously there is an alert to all GPs to be vigilant for new cases, and we have warned parents of the symptoms to look out for."

John Cain, an environmental health officer for Allerdale Borough Council, said milk was seized from the pasteurising unit at Scales Farm, which delivers to 300 homes.

He said: "There appears to have been a hiccup with one batch that went out."

There were 13 cases of E.coli poisoning in North Cumbria last year, but they were not linked.

E.coli 0157 causes gastroenteritis symptoms such as diarrhoea.

It usually clears up after a few days, but complications that may arise include inflammation of the bowel, and anaemia. In some cases, kidney problems may arise.

Dr Peter Tiplady on the E.Coli outbreak

Director of Public Health, Dr Peter Tiplady, said: "I believe we have got on top of the outbreak fairly quickly and I feel confident things are going well."

Professor Liam Donaldson, the Chief Medical Officer, said: "This is one of the most serious foodborne illnesses, to which children are particularly vulnerable."

He added that there was a small risk of secondary infection from the bug which can be passed from person to person.