An Overview of E. Coli

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Escherichia coli (E. coli) are bacteria found throughout our environment, in animals, and in humans. Many strains of E. coli are harmless, but some can cause illnesses ranging from mild to severe. Most commonly, E. coli can lead to intestinal infections that cause diarrhea, but it can also cause urinary tract infections, pneumonia, blood infections, and other illnesses.

Most pathogenic (illness-causing) E. coli live in the gastrointestinal tracts of animals such as cattle, goats, deer, and elk. They do not make the animals sick but when they are spread into the environment through the feces of these animals, they can contaminate the food we eat, causing a variety of symptoms. They can also contaminate beef when the animals are slaughtered. 

E.coli symptoms
Illustration by JR Bee, Verywell


The most common type of E. coli that causes illness is Shiga toxin-producing E. coli (STEC). The common symptoms of gastrointestinal (GI) disease caused by STEC are:

  • Diarrhea (may be bloody)
  • Stomach cramps
  • Vomiting
  • Occasional low-grade fever (usually not over 101 Fahrenheit)

Symptoms typically last five to seven days and can vary from mild to severe. The incubation period for STEC is usually three to four days but may be as little as 24 hours or as great as 10 days. The incubation period is defined as the time between exposure to the germs and the onset of symptoms.

Shiga toxin-producing E. coli is to blame for many foodborne illness outbreaks. The bacteria may live in the intestinal tracts of animals and is then spread to foods that humans eat (such as leafy vegetables) when manure is used as fertilizer or it gets in water that is used to irrigate fields. When an outbreak of STEC occurs due to contaminated food, there may be a widespread illness in communities. 

Hemolytic Uremic Syndrome

One of the more serious complications from an E. coli infection is hemolytic uremic syndrome (HUS). This occurs when kidney function diminishes following a GI illness. It occurs in 5% to 10% of people who have STEC infections.

Those with HUS are usually hospitalized because the kidneys may stop functioning completely, which can be life-threatening. Typically people who develop HUS recover within a few weeks but it can be fatal if not managed appropriately.


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This video has been medically reviewed by Robert Burakoff, MD, MPH.


If you have symptoms of a "stomach flu," your healthcare provider may do some testing to determine the cause. Although GI bugs usually go away on their own, your healthcare provider may order stool samples if your symptoms are unusual, such as appearing mucous-y and/or bloody, or lasting longer than a few days. Stool (also called fecal) testing can sometimes identify the particular germ that is causing the symptoms. Most labs can test for and identify Shiga toxin-producing E. coli.


There is no medication to take for gastrointestinal E. coli infections. Antibiotics are not helpful in treating this infection and using them can increase the chance of developing HUS.

If you have symptoms of an E. coli infection, it is important to try to stay hydrated. Supportive care to reduce the chance of dehydration is essential. If you develop bloody stool, are vomiting so much that you cannot keep any fluids down, or have a high fever, call your healthcare provider or seek medical attention immediately.

If E. coli is the cause of a different type of infection such as a urinary tract infection, blood infection, or respiratory infection, your treatment will likely include antibiotics.


E. coli is spread through the fecal-oral route, meaning tiny particles of fecal matter that contain E. coli are ingested by a person—usually through food or water—and they then become ill. Although it sounds disgusting, it is quite common and it is how most foodborne illnesses are spread.

To combat the spread of E. coli, it is very important to wash your hands. Washing them after using the bathroom, changing a diaper, before and after preparing food (especially raw meat), and after coming into contact with animals is the best way to prevent spreading the illness.

Health officials consider unpasteurized milk, "raw" or unpasteurized cheese, and raw meat that has been ground or needle tenderized to be high risk for spreading E. coli infections. Raw meats should be cooked to safe temperatures to ensure the bacteria is killed, and raw or unpasteurized dairy products should not be consumed at all to reduce the risk of contracting E. coli and other foodborne illnesses. 

You should also try to avoid swallowing water in places that could be contaminated with E. coli, such as swimming pools, baby pools, lakes, streams, and ponds. Public water parks have had documented cases of E. coli outbreaks as well, so do your best to avoid swallowing water in places like this where a lot of people are in the water and hygiene habits may be questionable. 

E. coli outbreaks can occur anywhere and affect anyone. Using good hand hygiene and food preparation habits can reduce the risk of spreading the bacteria and making others sick.

Although E. coli can be serious and many people worry about contracting this infection, most of the time it resolves on its own within a few days and doesn't require additional treatment. If you have symptoms that concern you, it's always best to check with your healthcare provider to figure out what is best for you.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Symptoms: E.coli. Updated November 20, 2017.

  2. National Kidney Foundation. Hemolytic Uremic Syndrome. 2016.

  3. Minnesota Department of Health. E. coli O157:H7 and HUS Fact Sheet. Updated May 2009.

  4. Centers for Disease Control and Prevention. Prevention. Updated September 20, 2017.

Additional Reading

By Kristina Duda, RN
Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.