What is E. coli?

Escherichia coli (E. coli) is a bacteria that is found in the intestines of both humans and animals. In most cases, this bacteria is harmless, and helps in the digestion of food. However, certain strains of E. coli can cause infection and symptoms, including diarrhea. Some of the infections can be dangerous.

What is an E. coli infection?

The strains of E. coli that cause symptoms of diarrhea are known as Shiga toxin-producing E. coli (STEC) and toxigenic E. coli. (The STEC that is most well-known and most often referred to is E. coli O157:H7.) Other strains can cause diseases such as pneumonia and urinary tract infections. The incubation period (the period between exposure to the E. coli bacteria and when symptoms appear) ranges from one to 10 days.

Who can get an E. coli infection?

An E. coli infection can affect anyone who comes in contact with the bacteria. People who are at greatest risk are the very young, the elderly, and people who have weakened immune systems.

What are the symptoms of an E. coli infection?

People who get infections with the STEC strain of E. coli can have the following symptoms:

  • Abdominal pains and cramps
  • Diarrhea and bloody stools
  • Discolored urine
  • Extreme fatigue
  • Loss of appetite
  • Vomiting

Symptoms can last from five to 10 days. An E. coli infection is usually not a serious health risk.

Some people who become infected with STEC develop a condition called hemolytic uremic syndrome (HUS). This is a potentially life-threatening illness that can affect the kidneys. Symptoms of HUS include infrequent urination, fatigue, and pale-looking skin. These patients need to be hospitalized because their kidneys may stop working.

What causes an E. coli infection?

The most common cause of an E. coli infection is contact with human or animal feces (the bacteria is found in stools). This contact can come about in several different ways, including the following:

  • Working with animals such as cows, goats, and sheep
  • Eating undercooked meat or raw vegetables (Meat can become contaminated with E. coli during the slaughtering process.)
  • Drinking unpasteurized milk or contaminated water (for example, drinking lake water while swimming)
  • Contact with the feces of infected people (for example, while changing a diaper)
  • Unsafe and improper food preparation (not washing hands before cooking food, unclean work surfaces in the kitchen)

In addition, E. coli infections can be spread from person to person in settings such as a day care center or a nursing home.

Last reviewed by a Cleveland Clinic medical professional on 09/27/2017.


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