Twenty-two people in Scotland have contracted a rare strain of salmonella in an outbreak affecting the whole of the UK and the Republic of Ireland.

Twenty-two people in Scotland have contracted a rare strain of salmonella in an outbreak affecting the whole of the UK and the Republic of Ireland.

A total of 82 people in the UK and eight in Ireland have fallen victim to Salmonella Agona since February.

The Scottish cases have occurred since June. Normally the strain affects only a handful of people in the UK each year.

Public health officials said the infection, which causes diarrhoea and vomiting, affected people from one to 79, but was prevalent mainly among young adults.

Scottish public health specialists have been assisting an investigation being co-ordinated by scientists in Ireland.

A spokeswoman for Health Protection Scotland, a division of the NHS which provides support on infections and environmental hazards, said: "Since June we have had 22 cases of Salmonella Agona in Scotland, spread across nine health board areas.

"We were made known that five of the people involved attended hospital. None of them was seriously ill and they have all been discharged. Public health experts are gathering food histories and other common factors that could help identify the source."

A spokeswoman for the Food Standards Agency in Scotland said: "The source of the outbreak is not yet known and the FSA, the Health Protection Agency and other relevant bodies, are working hard to identify its source.

"Consumer safety is a key priority of the agency so when we have any information useful to consumers we will publish it immediately."

The Food Safety Authority of Ireland (FSAI) said laboratory testing of foods was being carried out. It is continuing to investigate all potential sources of contamination and said that, as a precautionary measure, a company that supplies "implicated ingredients" to the catering industry had withdrawn these products from sale.

An FSAI spokesman said: "Normally in outbreaks there would be a close association of people infected perhaps people who had attended the same event, eaten at the same restaurant or bought food from the same shop.

"Because this is outbreak is spread over a large area and over a number of weeks and months, it is making the investigation more difficult."

Hugh Pennington, emeritus professor of bacteriology at Aberdeen University, said: "When you start to see an upsurge in the number of cases, that raises suspicions that there is probably some contaminated food out there."