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E. coli Infection

Escherichia coli (E. coli), particularly the type O157:H7, is a leading cause of foodborne illness. About 73,000 cases of infection and 60 deaths occur in the United States every year.

Hundreds of E. coli strains are harmless, including those that thrive in the intestinal tracts of humans and other warm-blooded animals. These strains are part of the protective microbial community in the intestine and are essential for general health. Other strains, such as E. coli serotype O157:H7, cause serious poisoning in humans. Cattle are the main sources of E. coli O157:H7, but these bacteria are also in other domestic and wild mammals.

E. coli O157:H7 can produce one or more kinds of poisons that can severely damage the lining of the intestines and kidneys. These types of bacteria, called Shiga toxin-producing E. coli (STEC), often causes bloody diarrhea and can lead to kidney failure, especially in young children or in people with weakened immune systems. Most illness has been associated with contaminated food or water, contact with an infected person, or contact with animals that carry the bacteria.

Other forms of E. coli that cause diarrheal disease include:

  • Enterotoxigenic E. coli (ETEC) is a leading bacterial cause of diarrhea in the developing world. Each year, about 210 million cases and 380,000 deaths occur, mostly in children, from ETEC, according to the World Health Organization. ETEC is the most common cause of traveler's diarrhea and affects troops on deployment overseas.
  • Enteropathogenic E. coli (EPEC) is a bacterial cause of persistent diarrhea that can last 2 weeks or more. It spreads to humans through contact with contaminated water or infected animals and is common in developing countries. In industrialized countries, the frequency of these organisms has decreased, but they continue to be an important cause of diarrhea, according to CDC.


Shiga toxin-producing E. coli (STEC) occurs when people consume contaminated foods or liquids. The U.S. Department of Agriculture, Food Safety and Inspection Service’s recall site lists food products contaminated with harmful E. coli.

The most common contaminated foods and liquids that have caused E. coli outbreaks include:

  • Undercooked or raw hamburgers
  • Salami
  • Produce such as spinach, lettuce, sprouted seeds
  • Unpasteurized milk, apple juice, and apple cider
  • Contaminated well water or surface water frequented by animals

STEC can also occur by:

  • Failure to wash hands thoroughly with soap and water following contact with an infected animal or animal waste, this can occur at farms, petting zoos, fairs, or even in your own backyard.
  • Failure to wash hands thoroughly with soap and water following contact with an infected person
  • Swallowing unchlorinated or underchlorinated water in swimming pools contaminated by human feces
  • Swimming in water with even very low levels of sewage contamination
  • Consuming contaminated food, water, or ice


Shiga toxin-producing E. coli (STEC) can cause the following symptoms:

  • Nausea
  • Severe abdominal cramps
  • Watery or very bloody diarrhea
  • Fatigue

STEC can also cause low-grade fever or vomiting. Symptoms usually begin from 2 to 5 days after eating contaminated food, or drink contaminated liquids. Symptoms may last for 8 days and most people recover completely from the disease.


The Centers for Disease Control and Prevention recommends testing anyone who suddenly develops diarrhea with symptoms of bloody stool. Health care providers use lab tests to identify Shiga toxin-producing E. coli in stool samples.


According to the Centers for Disease Control and Prevention, early supportive therapy is important for patients, especially those diagnosed with Shiga toxin-producing E. coli (STEC). There is no evidence that treatment with antibiotics is helpful, and taking antibiotics may increase the risk of Hemolytic Uremic Syndrome, a serious complication of STEC that can lead to kidney failure.



National Institute of Allergy and Infectious Diseases, USA.