FREDERICTON, New Brunswick – A 22-month-old boy has died of E. coli poisoning and health officials said Monday they were investigating other cases of contamination at a day care center in eastern Canada.

New Brunswick chief medical officer Dr. Wayne MacDonald said there were two other confirmed cases and a possible fourth case at the day care center in the coastal city of Saint John.

Officials said the boy, whose name was not released, died Saturday night or Sunday morning. The source of the contamination was not known, but officials said they did not believe it involved the tap water at the day care center. They did not give any information about the other cases.

E. coli bacteria that got in the water supply of an Ontario town last year killed seven people and sickened thousands.

The bacteria, often spread from the feces of cattle and other animals, cause flulike symptoms, diarrhea and dehydration.

E. coli is particularly dangerous for children, the elderly and people with weakened immune systems.