Health officials in South Australia have issued a warning after listeria was found in pastrami sold at a number of outlets.

SA Health's acting director of food and controlled drugs branch Joanne Cammans said meat producer Conroy's had detected listeria during routine testing of its pastrami and had issued a recall.

But Ms Cammans said there had been no reported cases of listeria infection from the meat.

The pastrami was being sold through a number of Foodland and IGA supermarkets, butchers, continental delis, bakeries, cafes and sandwich bars.

It is sold loose and has no distinctive packaging.

"While we have not received notification of anyone contracting listeria from the product, the infection can be extremely serious if it is contracted by the elderly, pregnant women or people with weakened immune systems," Ms Cammans said.

"Many people are exposed to listeria with often only mild illness resulting, but it can be more serious in the at-risk groups, so all South Australians at-risk should avoid eating the product."

Listeria infection starts with flu-like symptoms such as fever, chills, muscle aches, nausea, and sometimes diarrhoea.

People can start experiencing symptoms within a few days, but they can take up to six weeks to emerge after eating a contaminated product.