A woman works to sterilize meat processing and packaging equipment at the Maple Leaf Foods plant in Toronto August 21, 2008. Canadian health officials searched for more clues on Thursday into the source and extent of a listeriosis food poisoning outbreak that has made more than a dozen people sick and caused one death. The company and health officials found listeria monocytogenes in two products made by the company, although genetic testing has not yet determined whether it is the same strain that caused the outbreak, associate chief medical officer David Williams said.