At least two people were killed and dozens sickened by E. coli outbreaks in Canada and the United States that the authorities in Canada have linked to romaine lettuce.
Health officials in the United States are not yet ready to blame the U.S. outbreak to the leafy green. Still, they say, the Canadian finding has proved helpful and both outbreaks appear to have been caused by related strains of the bacteria, suggesting the possibility of a shared source.
“They've done a really thorough job there, and I think that gave us a really good clue to start with,” Dr. Matthew Wise, who oversees investigations into such outbreaks for the Centers for Disease Control and Prevention, said in a telephone interview Friday.
In all, at least 58 people in both countries have been sickened, and two — one in California and one in Canada — have died. In the United States, the CDC has so far linked at least 17 reports of illness in 13 states to the outbreak.
The Public Health Agency of Canada said in a statement last week that it was investigating 41 cases of illnesses linked to E. coli from November and December.
Most of those patients reported eating romaine lettuce before they became ill, the agency said, adding, “Individuals reported eating romaine lettuce at home, as well as in prepared salads purchased at grocery stores, restaurants and fast food chains.”
U.S. officials have not yet issued recommendations to avoid any particular product because they are still collecting information on the outbreak. Consumer Reports, the nonprofit advocacy organization, said it was urging shoppers to avoid the lettuce as a precaution.
“Even though we can’t say with 100 percent certainty that romaine lettuce is the cause of the E. coli outbreak in the U.S., a greater degree of caution is appropriate given that lettuce is almost always consumed raw,” James Rogers, the director of Food Safety and Research, said in a post on the group’s website.
The widespread nature of the U.S. outbreak suggests that the cause was not limited to a restaurant or particular area, Wise said.
“When we see this pattern of illnesses, we certainly would default to thinking that this was a commercially distributed product that was contaminated,” he said.
Symptoms of E. coli infection include fever, abdominal pain, bloody diarrhea, and, less commonly, a syndrome that can lead to kidney failure. In such outbreaks, young and older people and those with weakened immune systems are most likely to have the most severe symptoms.
E. coli, short for Escherichia coli, live in human and animal intestines and can contaminate fruits and vegetables when they come in contact with feces from infected animals, according to the Public Health Agency.
That contamination can happen at any point along the journey from farm to table. Most E. coli strains are harmless to humans.