The Canadian Food Inspection Agency (CFIA) says that they are working with public health officials and the U.S. FDA to determine the source of the romaine lettuce that ill individuals were exposed to.
A unsafe E.coli outbreak has already sickened 32 people across 11 states, with almost half requiring hospitalization.
On Tuesday, US health officials issued an unusually broad warning against all types of romaine lettuce amid an E. coli outbreak.
In its warning, the CDC advised consumers, restaurants and retailers not to eat, serve or sell any romaine lettuce.
One of those reported sick had suffered kidney failure. Because of frost, their own crop of lettuce is finished, so they sourced this week's supply of romaine from a small greenhouse grower in Leamington.
"Investigations on the actual source of the bacteria causing the outbreak is ongoing". Nothing definitive yet, but the early betting is that it came from California's Monterey County or the surrounding growing season, where the romaine lettuce growing season is in full swing. "It's very unusual for these public agencies to recommend that consumers completely avoid a product because it may be a health risk". "Most of the romaine lettuce being harvested right now is coming from the California region, although there's some lettuce coming in from Mexico". The Centers for Disease Control and Prevention has confirmed a total of five deaths in the last E. coli outbreak from romaine lettuce.
The centre also held all romaine lettuce imported from the two countries starting from Thursday for testing, a spokesman said. "The goal of this effort is to learn any information about the geographic region or specific farms that may be tied to this outbreak".
"So by the time they're actually doing trace-back, there is no packaging left, there's no product left", Horsfall said.
The association said it is pulling together a group of food safety experts from the produce industry to help pinpoint the source of the outbreak. This means that the ill people were more likely to share a common source of infection.