The Canadian Food Inspection Agency is warning the public not to eat certain Champ's Mushrooms brand Sliced Crimini Mushrooms that may be contaminated with listeria. The Aldergrove-based company's mushrooms have a packed-on date of Aug. 10 and have been distributed in B.C. Food contaminated with the Listeria monocytogenes bacteria may not look or smell spoiled but can cause listeriosis. Listeriosis can cause high fever, severe headache, neck stiffness and nausea. Pregnant women, the elderly and people with weakened immune systems are particularly at risk. There have been no reported illnesses associated with the consumption of the affected mushrooms.