By: Heather Williams
Both outbreaks are considered over, but the FDA is still pursuing the culprit.
The Canadian E. coli outbreak linked to romaine lettuce seems to be over according to the January 10, 2018 update from the Public Health Agency of Canada. The FDA investigation continues in the United States. At this time the outbreak has affected 24 people across 15 states in the United States. Though the end seems to be nearing. The last reported illness on record began on December 12, 2017.
As this outbreak made its way to California, Connecticut, Illinois, Indiana, Maryland, Michigan, Nebraska, New Hampshire, New York, Ohio, Pennsylvania, Vermont, Virginia, and Washington, a few have experienced serious complications. At least two have been diagnosed with hemolytic uremic syndrome, or HUS, which is a type of kidney failure associated with E. coli infection. One person in California has died as a result of this illness.
The likely source of the outbreak in the United States appears to be leafy greens, but officials have not specifically identified a type of leafy greens eaten by people who became ill. Leafy greens typically have a short shelf life, and since the last illness started a month ago, it is likely that contaminated leafy greens linked to this outbreak are no longer available for sale. Canada identified romaine lettuce as the source of illnesses there, but the source of the romaine lettuce or where it became contaminated is unknown.
The State and Local Health officials conduct interviews of those linked to the outbreak. While romaine was strongly indicated in Canadian patients, the indication was not as strong in American patients. Though a link was present. According to the Center for Disease Control and Prevention (CDC), 56% of those interviewed reported eating romaine lettuce in the week prior to becoming ill. The CDC also conducts surveys with healthy individuals to identify if links are by happenstance or a true indicator of outbreak contamination source. In this case, 46% of surveyed healthy individuals indicated eating romaine lettuce. This is the reason the United States has not issued any recalls or pushed for romaine lettuce as a source. Though popular opinion is that over half of those who became ill report eating romaine, there is a clear connection. As a result of indications from Canada, some businesses have erred on the side of caution and temporarily removed the product from the menu.
The Problem with Interviews
While patient interviews often link contaminated foods to an outbreak, sometimes the human error can creep into the process. Oftentimes people’s memories aren’t all that reliable. Generally, if a person remembers consuming a food, they have. Though many times people can forget that they have eaten a particular food. Do you remember what you ate last week? Imagine being sick and asked that question.
The other problem with patient interviews can come in the form of holes in the story. “I don’t like lettuce, so I don’t eat it” could actually be “I removed the lettuce from my burger last week because I don’t like lettuce.” In this case, the contaminated food item directly came in contact with a food item that was consumed, though the patient didn’t directly eat it.
Other times a person may not even know that their food was passively contaminated. Consider a salad bar where tongs are used between multiple lettuce types. Contaminated foods may be stored with other ready-to-eat foods, causing cross contamination that may result in the spread of illness.
There is a bigger picture that the person interviewing may not see. Ignoring a trend in interviews, even though it is not close to 100% can have a potentially negative impact on discovering the source of the outbreak. Discovering the source is the ultimate goal so that it can be removed from the public to prevent future illness from occurring.
The Nature of Lettuce
According to a 2015 study, we eat 24.5 pounds of lettuce per person per year. Of that weight, 45% of the lettuce consumed is leafy lettuce (romaine, butterhead, and other leafy types). A small 5.4% of that leafy lettuce is imported into the United States. It’s safe to say that most of the lettuce we consume is domestic and not imported.
Lettuce can be produced year round in the United States, primarily in California and Arizona. This beautiful green produce is a cool loving crop that enjoys moderate daytime temperatures around 73 ⁰F and cool nights (45 ⁰F).
Romaine is primarily consumed raw and is often the main ingredient of salads, but could also be a garnish on a sandwich or burger or even thrown into a smoothie. You may notice it has no sell by date or expiration date when you purchase it from the store. I personally have never seen a sticker giving me any idea of when to toss it. The shelf-life of romaine lettuce (and other lettuces) depends on a variety of factors. This includes but is not limited to the temperature of the refrigerator (too warm or too cold), how long the product stayed at room temperature, whether the product is bagged or open to the air, and/or how it is handled. According to Ag Marketing Research Center a head of romaine lettuce has a shelf life of between 7 and 10 days. Once the lettuce is chopped or removed from the head, the shelf life reduces to 3 to 5 days. With such a short shelf life compared to illness being reported, it seems that tainted product is still in circulation.
UnsafeFoods will continue to monitor this issue and update as more information becomes available.