The province's Chief Medical Officer of Health made an announcement, warning Ontarians not to consume Siena-brand Prosciutto Cotto Cooked Ham as it may be infected with Listeria.

The warning came when two Ontarians were reported to be hospitalized, while another two deaths are being investigated - in relation to a listeria outbreak tracked to a Toronto deli meat maker.

It is revealed that the Sienna brand ham was sold to consumers after Jan. 11, 2010 in delicatessens and grocery stores, with the best before date of Mar. 8 and Mar. 22, 2010.

Packages of prosciutto cotto cooked ham and mild cacciatore salami made by Siena Foods Ltd. are speculated to be the possible culprit behind the outbreak.

As a part of the investigation, the salami manufactured by the company was recalled in December, while, the ham was recalled early Friday.

Both were reported to have sold to delis, grocery stores, specialty food stores and supermarkets after January 11.

"We do not know what the source of infection is in the majority of these individuals and we may never know," quoted Dr. Arlene King. "Why there's an overall increase in (listeria cases), we don't know and the investigation is ongoing for that reason."