In the United States, there have been at least two E. coli outbreaks each year since 2009. (1) But only about 20 percent of E. coli cases occur as part of a recognized outbreak. (2)
Identifying E. coli Outbreaks
Scientists first recognized E. coli O157 as a pathogen in 1982. But the public had little awareness of the bacteria until 1993, when undercooked hamburgers from the Jack in the Box fast-food chain gave E. coli O157 to more than 700 people across multiple states. The devastating outbreak killed four children, according to a 2005 article in Emerging Infectious Diseases. (3) In an effort to help prevent such a large outbreak from happening again, the Department of Agriculture implemented new regulations a few years later, which were designed to help prevent contaminated meat and poultry in processing plants from reaching the public. Around the same time, the CDC implemented a nationwide surveillance program to identify foodborne outbreaks more quickly than had ever been possible. The program, called PulseNet, is a collaboration between 83 laboratories across the United States (there’s also an international version of PulseNet that includes 88 countries). (4) With PulseNet, technicians in various laboratories (there is at least one in each state) identify a patient with a specific pathogen, such as E. coli. They then zero in on the DNA “fingerprint” of said pathogen, which is then uploaded to the database that can be accessed by each lab across the country. Here, microbiologists and epidemiologists can review laboratory reports and fingerprints and look for patterns that could indicate that a patient’s illness is part of a larger outbreak. (4) This system has been instrumental in preventing an estimated 270,000 illnesses every year from the three most common causes of foodborne illness: salmonella, E. coli O157, and listeria. (5) For example, in April 2010, PulseNet alerted the New York State Department of Health that there were two E. coli clusters at universities in Michigan and Ohio. The next day, a similar illness cluster appeared in a New York college. Since the New York leg of PulseNet had easy access to the lab findings and DNA fingerprints in the Michigan and Ohio cases, they were able to quickly discover that the clusters were connected. After further investigation, the CDC was able to trace the outbreak to a specific shredded romaine distributor that provided the contaminated produce to each of the colleges in question. In the end, all of the remaining lettuce was successfully destroyed, and a widespread outbreak was sidestepped. (6) The CDC has implemented other programs, such as the Foodborne Diseases Active Surveillance Network (FoodNet) to track, study, and identify the sources of outbreaks. FoodNet is specifically designed to home in on nine bacterial and parasitic pathogens transmitted commonly through food, including E. coli. (7) In addition, the FDA requested that all romaine lettuce on the market, including in restaurants and grocery stores, should be destroyed. This precautionary request was made while officials were still investigating the source for the outbreak, but a full market withdrawal was the fastest way to remove any potentially contaminated produce. The FDA believed that this “clean break” action was effective in removing potentially contaminated romaine from circulation, thus thwarting additional outbreaks. (8) In the end, CDC officials were able to narrow the warning to any romaine lettuce that was harvested from the central coastal growing regions of northern and central California. (9) Knowing where produce was grown and harvested is a very important part of the outbreak puzzle. When consumers know where their food is from, they are better able to avoid contaminated products. Plus, this facilitates product withdrawals and tracing. Currently, the Food and Drug Administration (FDA) urges food industries, like growers and distributors, to provide unambiguous information on their food packaging that shows where the lettuce was grown and when it was harvested. This will improve the ability of the FDA to provide even more targeted information to consumers in the event of a future E. coli outbreak. The FDA has commitments from the romaine lettuce industry that such labeling will continue and soon become the standard. (8)
Recent Beef-Related E. coli Outbreaks
In September 2018, a multistate outbreak of Shiga toxin–producing E. coli O26 infections linked to ground beef from Cargill Meat Solutions in Fort Collins, Colorado, occurred. While less severe than the infamous Jack in the Box outbreak, 18 people were infected across four states, with victims ranging in age from 1 to 75. By the conclusion of the outbreak, six individuals were hospitalized and one person was killed. (10)
How You Can Help if an Outbreak Occurs
If you believe that you have an E. coli infection or are part of an outbreak, ask your healthcare provider about testing you for foodborne disease via a stool sample. The test results can then be uploaded to the PulseNet database. (11) At the same time, report your illness to the local health department — or ask your healthcare provider to do so. (Visit your state health department website for information on how to proceed.) Finally, if you become ill, write down everything you ate (and where you ate it) the week leading up to your illness. In the event of an outbreak, you may be interviewed about these matters. (11)
The Timeline of Pinpointing an E. coli Outbreak
Up to 22 days can pass from the time that the first individual falls ill from a potential E. coli outbreak to the time the public becomes aware of it. Here’s why:
Time lag for symptoms to develop For example, it can take up to three days after consumption of food contaminated with E. coli O157 for a person to fall ill.Delay in calling the doctor The time between experiencing the first symptoms of E. coli illness until a person seeks medical care is typically one to five days.Time to diagnosis It can take one to three days to get lab results from a provided stool sample.Shipping samples It can take up to seven days for a laboratory sample to arrive at a state public health department where DNA fingerprinting takes place.DNA fingerprinting The start-to-finish process of DNA fingerprinting can take two to four days. (12)
Other E. coli Outbreaks
There have been other sources of recent E. coli outbreaks beyond those stemming from ground beef or romaine lettuce. Some of those include:
I.M. Healthy SoyNut Butter In 2017, 32 people fell ill and 12 were hospitalized from I.M. Healthy brand’s SoyNut Butter. There were no deaths. (13)Flour In 2016, 63 people fell ill and 17 were hospitalized from flour most likely produced at a General Mills facility in Kansas City, Missouri. There were no deaths. (14)Sprouts In 2016, 11 people fell ill and two were hospitalized from an outbreak in alfalfa sprouts. And in 2014, 19 people fell ill and eight were hospitalized from an outbreak in clover sprouts. There were no deaths in either case. (15,16)Costco Rotisserie Chicken Salad In 2015, 19 people fell ill and five were hospitalized from Costco’s rotisserie chicken salad. The specific food source was never identified, but the celery and onion diced blend was suspected. There were no deaths from this outbreak. (17)Chipotle Mexican Grill restaurants In 2015, 55 people fell ill and 21 were hospitalized after eating at Chipotle. The specific food source was not identified. There were no deaths from this outbreak. (18)
Additional reporting by Joseph Bennington-Castro.
