Canada's food watchdog is warning Ontarians to avoid consuming Santa Lucia brand ricotta cheese because it may be tainted with listeria monocytogenes.

The recall affects cheese sold in 500-gram packages with a best before date of Jan. 1, 2009, and a lot number of 477.

No associated illnesses have been reported.

People who eat foods contaminated with listeria may carry the bacteria and not develop listeriosis. Those most vulnerable to developing the disease include the elderly, infants and patients with a compromised immune system.

Pregnant women who develop listeriosis in their first trimester are at risk of miscarriage while women in the later stages of pregnancy are at risk of delivering a stillborn or acutely ill infant.

Consumers with questions can call the Toronto-based manufacturer, International Cheese Co. Ltd, at 416-769-3547 or the Canadian Food Inspection Agency at 1-800-442-2342.