Canada Friday disclosed the difficulty facing health officials in finding the source of an ongoing North American outbreak of E. coli O157:H7. They also reported more illnesses in Canada.

Individuals who are sick say they ate romaine lettuce before their illnesses occurred, the Public Health Agency of Canada reports. Individuals reported eating romaine lettuce at home, as well as in prepared salads purchased at grocery stores, or from menu items ordered at restaurants and fast food chains.

“Furthermore, it is important to remember that we are looking for a small amount of lettuce contaminated with E. coli O157 amidst the large volume of safe romaine lettuce that is purchased, served and consumed in Canada on a daily basis,” the Public Health Agency of Canada reported.

It says that since April 1, 2017, the Canadian Food Inspection Agency has tested more than 2,000 samples of imported fresh vegetables and salads, including romaine lettuce and pre-packaged salads containing romaine lettuce, as part of its regular microbiological surveillance program.

Canadian officials believe that since no positive test results from that level of testing, low levels of contamination are likely.

Earlier this week Canada exposure had 18 confirmed cases limited to the provinces of Ontario and Quebec.

Canadian officials Friday said that as of November 23, there have been 22 confirmed cases of E. coli illness investigated in Ontario (4), Quebec (17), and New Brunswick (1).

Thirty-two lab-confirmed illnesses from the same E. coli O157:H7 outbreak have been reported from 11 U.S. states. Of 26 U.S. patients for whom the information is available, 13 have been hospitalized. One person developed hemolytic uremic syndrome, a type of kidney failure. No deaths have been reported in either country.

In the United States, the federal Centers for Disease Control and Protection (CDC) on Nov. 19 said consumers, restaurants, and retailers should not eat, serve or sell any romaine lettuce until federal food safety detectives get to the bottom of this outbreak.

The Public Health Agency of Canada says  “as the risk is ongoing, it is advising individuals in Ontario, Quebec, and New Brunswick to avoid eating romaine lettuce and salad mixes containing romaine lettuce until more is known about the outbreak and the cause of contamination. Residents in impacted provinces are also advised to discard any romaine lettuce in their home and to properly wash and sanitize any containers or bins that have come in contact with romaine lettuce.”

Epidemiological evidence from both the United States and Canada indicates that romaine lettuce is a likely source of all 54 Illnesses in the international outbreak.

The current outbreak appears to be ongoing as illnesses linked to romaine lettuce continue to be reported, Canadian officials say. “These recent illnesses indicate that contaminated romaine lettuce may still be on the market, including in restaurants, grocery stores and any establishments that serve food. At this time, the investigation evidence in Ontario, Quebec, and New Brunswick suggests that there is a risk of E. coli infections associated with eating romaine lettuce.

Ill people in this outbreak were infected with E. coli bacteria with the same DNA fingerprint as the E. coli strain isolated from sick people in a 2017 outbreak linked to leafy greens in the United States and to romaine lettuce in Canada.

This latest outbreak is not related to another multi-state outbreak of E. coli O157:H7 infections earlier this year that was also linked to romaine lettuce, according to U.S. officials. That outbreak, declared over in late June, sickened 210 people in 36 states. Five people died

In Canada, based on the investigation findings to date, exposure to romaine lettuce has been identified as a source of the current outbreak, but the cause of contamination has not been determined, officials say.

Laboratory analysis indicates that the illnesses reported in this outbreak are genetically related to illnesses reported in a previous E. coli outbreak from December 2017 that affected consumers in both Canada and the U.S.

This is confirmation that the same strain of E. coli is causing illness in Canada and the U.S. as was seen in 2017 and it suggests there may be a reoccurring source of contamination. Investigators are using evidence collected in both outbreaks to help identify the possible cause of the disease in these events.

Individuals confirmed as patients in the current outbreak became sick between mid-October and early November 2018. No deaths have been reported. Individuals who became ill are between 5 and 93 years of age. The cases are evenly distributed among male and female individuals.

“We know Canadians want reassurances about the safety of the foods they eat and feed their families,” This is why the CFIA has increased its sampling and testing of romaine lettuce across Canada in light of the current situation. The sampling program involves romaine lettuce from different growing regions and different harvest periods.

E coli transmission

Canada explains it this way:  “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, water, animals or improperly composted manure.

“Lettuce can also be infected 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.”


People infected with E. coli can have a wide range of symptoms. Some do not get sick at all, though they can still spread the infection to others. Others may feel as though they have a bad case of upset stomach. In some cases, individuals become seriously ill and must be hospitalized.

The following symptoms can appear within one to ten days after contact with the bacteria:

  • nausea
  • vomiting
  • a headache
  • mild fever
  • severe stomach cramps
  • watery or bloody diarrhea

Most symptoms end within five to ten days. There is no real treatment for E. coli infections, other than monitoring the illness, providing comfort, and preventing dehydration through proper hydration and nutrition. People who develop complications may need further treatment, like dialysis for kidney failure. You should contact your health care provider if symptoms persist.

All hands are on deck for this outbreak investigation, including The Public Health Agency of Canada, CFIA, Health Canada, CDC, FDA, and state and provincial agencies.

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