How to Handle E. Coli Outbreaks

How to Handle E. Coli Outbreaks

Back in the Spring of 2018, if you were shopping for Romaine lettuce in your grocery store, you most likely noticed the empty spaces in the Romaine section. The Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration (USDA), and public health and regulatory officials in several states investigated the multi-state outbreak of the dangerous Escherichia coli O157:H7 that infected over 50 people from 16 different states. People first began to get sick on March 13, 2018 and the CDC began their investigation on April 10, 2018.  


A more recent multi-state outbreak occurred September 2019 to December 2019. Evidence showed that romaine lettuce from the Salinas Valley growing region in California was the likely source of this outbreak.  


This article will explain e. coli and how to handle e. coli outbreaks. 

What is  E. Coli? 

E. coli is a large group of bacteria that are found throughout our environment as well as within our own digestive system. E. coli was first identified by the German microbiologist and pediatrician Theodor Escherich when he studied the role of bacteria in the digestive tracts of infants in 1884. 

Bacteria from animals’ intestines during the slaughtering process can be spread to poultry and meat products. Poor sanitation of water can cause the water to contain bacteria originating from human or animal waste. If you drink contaminated water or swim in it, you can acquire the bacteria. E. coli can also be spread when an infected person fails to wash their hands after a bowel movement. The bacteria spreads when that person touches another person or touches food. Person-to-person spreading is more frequent in nursing homes, schools, and child care facilities. People who work with farm animals such as cows, goats, and sheep, have a higher risk of infection. Those who work closely with animals should wash their hands regularly and thoroughly. 

The Most Dangerous Strain 

Most strains of E. coli are harmless, but some types can lead to diarrhea, urinary tract infections, respiratory illness, or pneumonia. The strain of E. coli that is the most dangerous to humans is E. coli O157:H7, known as a STEC or ‘Shiga toxin-producing’ E. coli. STEC is most often found in the digestive tracts of cattle, goats, sheep, deer, and elk. STEC doesn’t make these animals sick, but it can cause human illness. Sometimes other types of animals, like pigs and birds, pick up STEC from the environment and can spread it in their feces. 


STEC is especially dangerous because it can easily contaminate our food supply. Vegetables like Romaine lettuce can be contaminated via fertilizer and water, or through contact with livestock-associated birds. STEC can also be transmitted to humans via the fecal contamination of meat during butchering and packaging. 

Why is STEC So Dangerous? 

The Shiga toxin produced by STEC attacks small blood vessels inside our body, kills intestinal cells, and causes bloody diarrhea and severe abdominal pain. Sometimes people affected by STEC believe they have the flu and don’t seek treatment. 


STEC can sometimes lead to hemolytic uremic syndrome (HUS), a potentially-deadly condition that can involve widespread blood clots and hemolytic anemia (the abnormal breakdown of red blood cells), thrombocytopenia (a lack of blood platelets which reduces the blood’s ability to form clots), and renal failure. 


According to CDC data, the spring 2018 E. coli outbreak associated with Romaine lettuce was the first that year. Since 2006, typically 2-3 outbreaks occur each year in foods including alfalfa sprouts, leafy greens, ready-to-eat salad, ground beef, cheese, and pre-packaged cookie dough. 

What was the Cause of the Spring 2018 Outbreak? 

Investigators narrowed down the source of the E. coli O157:H7 bacteria to Romaine lettuce grown in Yuma, Arizona.  Over 90% of the lettuce in your grocery stores during the winter months is grown in Yuma, in the southwestern corner of Arizona where the sun shines 350 days during the year.  

Actions to Take if There is Another Outbreak? 

It’s important to know how to handle an e. coli outbreak. When an outbreak occurs, follow the directions of the CDC. For example, with the contaminated Romaine, people were advised to throw out all uneaten Romaine lettuce, both whole heads of Romaine as well as bagged, chopped Romaine and salad mixes that contained Romaine lettuce unless you knew for sure that it was not involved in the contamination. Since packaging labels typically don’t identify growing regions, if you’re unsure, it’s safest to throw out the lettuce. Restaurants and retailers were advised not to sell or serve Romaine lettuce in any form unless they knew for certain that it was not grown in the area where the outbreak originated.  


If you have diarrhea that lasts for more than 3 days, or have diarrhea with high fever and bloody stools, or are vomiting and can’t keep down liquids, it’s important to contact your healthcare provider. Very young children, the elderly, and anyone with a chronic health condition should be especially vigilant and contact their healthcare providers immediately. 

Wash your hands after using the bathroom, changing diapers, or before preparing food. 

Wash your hands after contact with animals in any location, including farms, petting zoos, fairs, or your own backyard. 

Cook meat thoroughly to an internal temperature of at least 160°F/70°C. It’s best to use a thermometer, as color is not a very reliable indicator of “doneness.” 

Do not drink unpasteurized milk, dairy products, or juices (like fresh apple cider). 

Avoid swallowing water when swimming or playing in lakes, ponds, streams, swimming pools, and backyard ‘kiddie’ pools. 

Prevent cross-contamination in your kitchen by thoroughly washing counters, cutting boards, and utensils after they touch raw meat. 


Don’t defrost meat on the counter. Always defrost meat in the refrigerator or microwave.  

Wash your hands before and after preparing fruits and vegetables. 

Wash or scrub all fruits and vegetables under running water before eating, cutting, or cooking.  

 Fruits and vegetables labeled “prewashed” do not need to be washed again at home.  

Use separate cutting boards for fruits and vegetables and for raw meats, poultry, seafood, or eggs.  

 Use separate plates and utensils for cooked and raw foods. 


Store fruits and vegetables away from, and not next to or below, raw meat, poultry, or seafood. These items can drip juices that may have germs. 

How to Clean Your Hands Thoroughly 

Keeping hands clean is so important that it can’t be emphasized enough. It helps to avoid getting sick and spreading germs to others. The recommended way is to wet your hands, apply soap, and lather by rubbing your hands together. Make sure to clean the back of your hands, between your fingers, and under your fingernails. After about twenty seconds, rinse your hands well. 


This information is for educational purposes only. The statements have not been evaluated by the Food and Drug Administration and are not intended to diagnose, treat, cure, or prevent any disease. Consult your physician if you have any question regarding a medical condition.


  1. Centers for Disease Control and Prevention. Multistate Outbreak of E. coli O157:H7 Infections Linked to Romaine Lettuce. last updated 4-20-18. Accessed 4-24-18. 

  2. Centers for Disease Control and Prevention. E. coli Questions and Answers. last updated 2-26-18. Accessed 4-23-18. 

  3. Blount ZD. The unexhausted potential of E. coli. eLife. 2015;4:e05826. doi:10.7554/eLife.05826. 

  4. Centers for Disease Control and Prevention. Reports of Selected E. coli Outbreak Investigations. last updated 4-20-18. Accessed 4-23-18 

  5. Kurt D. Nolte, University of Arizona. Winter Lettuce Production, Yuma Arizona. Accessed 4-24-18.