This undated image provided by the Centers for Disease Control and Prevention shows salmonella bacteria in a petri dish. (CDC/Canadian Press)

Alberta Health Services says a salmonella outbreak in southwestern Alberta is spreading.

About 30 cases were confirmed in and around the Lethbridge area Monday.

The organization’s south zone medical officer of health, Dr. Vivian Suttorp, says new cases have cropped up since then — mostly spread by household contact.

"I can't give you an exact number at this point in time. I think, fair enough to say, that we have some individuals who are perhaps more ill than others who are seeking medical attention and where stool samples will be done. There's a whole other group out there who are not seeking medical attention but who also have similar symptoms."

Suttorp said they are working with the First Nations and Inuit Health Branch and their first priority is stopping the spread.

She says the best way to do that is wash your hands, cook food thoroughly and avoid cross contamination.