There are currently 41 cases of E.coli infections in five eastern provinces linked to romaine lettuce. While @CFIACanada is testing romaine lettuce for the presence of E. coli as part of the food safety investigation, these illnesses appear to be ongoing and indicate that contaminated romaine lettuce may still be on the market (including in restaurants, grocery stores, and any establishments that serve food). 
Because of the ongoing risk in eastern Canada, the Public Health Agency of Canada is advising individuals in Ontario, Quebec, New Brunswick, Nova Scotia, and Newfoundland and Labrador to consider consuming other types of lettuce, instead of romaine lettuce, until more is known about the outbreak and the cause of contamination.
E. coli are bacteria that live naturally in the intestines of cattle, poultry and other animals. A common source of E. coli illness is raw fruits and vegetables that have come in contact with feces from infected animals. Leafy greens, such as lettuce, can become contaminated in the field by soil, contaminated water, animals or improperly composted manure.
Lettuce can also be contaminated by bacteria during and after harvest from handling, storing and transporting the produce. Contamination in lettuce is also possible at the grocery store, in the refrigerator, or from counters and cutting boards through cross-contamination with harmful bacteria from raw meat, poultry or seafood. Most E. coli strains are harmless to humans, but some varieties cause illness.
