S. typhimurium - one of the 2,500 types of Salmonella

They say more cases may emerge, but these would be people who ate contaminated food before the possible source of the infection was closed.

Laboratory tests have strengthened the link between the cases and Robson's Fresh Foods, in Stanley.

The shop was served with an emergency prohibition notice on 29 July.

Laboratory results

The outbreak was investigated by public health and environmental health officials from Derwentside District Council, Derwentside Primary Care Trust and the Health Protection Agency.

Dr Deb Wilson, chair of the Outbreak Control Team, said: "The co-ordinated efforts of the agencies involved quickly identified the outbreak and took effective measures to protect the public health.

"Further laboratory results have strengthened the link between the cases and consumption of products purchased from Robson's Fresh Foods.

"Throughout the investigation the proprietor has co-operated fully."

Salmonella infections cause a range of symptoms including diarrhoea, headache, nausea and fever.