Many Escherichia coli (E. coli) bacteria exist in the environment and in the human gut. Most E. coli bacteria are harmless or cause mild cramping and diarrhea in infected people. However, some strains of E.coli bacteria can release toxin. These are referred to as shigatoxin-producing E. coli (also referred to as enterohemorrhagic E. coli [EHEC] and verotoxigenic E. coli [VTEC]). E. coli O157:H7 is the most well-known of the toxin-producing E. coli. These toxin-producing E. coli can cause more severe diarrhea, bloody diarrhea, serious complications and death. ‎

• Toxin-producing E. coli bacteria can infect humans when we eat contaminated food or water or though contact with infected animals.
• The bacteria that produce these toxins are found in the gut and manure of cattle, and sometimes that of sheep, goats and deer. The manure can contaminate meat, other foods and water sources.
• When animals are butchered, sometimes the gut is nicked by the knife, contaminating the carcass and meat. Human infection is often due to eating undercooked hamburger or other meat.
• Cattle and other animal manure can contaminate produce growing in the field and dairy products made with unpasteurised or raw milk. Outbreaks of toxin-producing E. coli affecting BC residents have been caused by contaminated lettuce and unpasteurised Gouda cheese.
• Some foods are considered to carry such a high risk of contamination that health officials recommend people avoid them completely. These foods include unpasteurized (raw) milk and unpasteurized apple cider.
• Drinking contaminated water and swimming in contaminated water has also occasionally caused infection and outbreaks.
• Direct contact with an infected animal or its environment (e.g. pen) can also lead to infection and outbreaks.

• E. coli infection may cause mild to severe symptoms including watery diarrhea and stomach cramps. In severe cases, diarrhea may become bloody.
• Fever is rare.
• Symptoms start an average of 3 to 4 days (range: 2 to 10 days) after exposure to the bacteria, and usually last between 5 to 10 days.

• Approximately 15% of children, and a smaller percentage of adults who are diagnosed with STEC infection develop a potentially life-threatening complication known as hemolytic uremic syndrome (HUS).
• Clues that a person is developing HUS include decreased frequency of urination, feeling very tired, and losing pink colour in cheeks and inside the lower eyelids. Persons with HUS should be hospitalized because their kidneys may stop working and they may develop other serious problems. Although many persons with HUS recover within a few weeks, about 50% need dialysis and some suffer permanent damage or die (about 5%).
• Although pathogenic E. coli are usually gone from the feces by the time symptoms disappear, they can go on being excreted in stools for weeks or months. Careful hand washing is important to prevent the spread of this illness, and people who work in high risk occupations may need to provide stool samples free of the bacteria before returning to work.

• Diagnosis is done through culturing of stool samples.
• If the bacteria are not detectable in the stool, it may be possible to detect shigatoxin, an indication that infection caused by toxin-producing E. coli has occurred.
• To detect outbreaks, "fingerprinting" can be done to determine if all the E. coli detected in samples are of the same strain.

• Anyone who has bloody diarrhea should see their doctor.
• Drinking lots of clear fluids is important.
• If you or your child have symptoms of infection, it is important to see a doctor. This is especially important if someone has bloody diarrhea. Your doctor may ask for a stool sample to test for E. coli and will determine if treatment is necessary.
• Non-specific supportive therapy, including hydration, is important.
• Antibiotics and anti-diarrheal drugs should not be used to treat this infection, unless your doctor prescribes them, since taking antibiotics may increase the risk of HUS.

• If you think you have an E. coli infection, see your family doctor for testing, advice and treatment. E. coli is passed in the feces; therefore, people with diarrhea that may be due to an infectious illness should not go to work or school.
• If an infected person is a food handler, health care worker or works in or attends a day care, it is possible for them to transmit E. coli to others in these settings. A public health official will contact them or their parents/guardians to discuss when they can return to work or day care (basically when two stool samples are clear). See the guideline on Exclusion of Enteric Cases and their Contacts from High Risk Settings.

• Peel any fruits or vegetables to be eaten raw, or wash them well in plenty of clean water.
• Ground meat and rolled roasts (e.g. beef roulade) are particularly hazardous, compared to whole pieces of meat like steaks and whole roasts. This is because the bacteria which get onto the surfaces of the meat during the butchering process get mixed right through the meat when it is ground up. Bacteria on the surface of whole cuts used in beef roulade are covered by other cuts which are rolled and tied together. Beef roulade and ground meats must be cooked to well done.
• Use separate cutting boards for raw and ready-to-eat foods.
• When you take raw meats out to your barbecue, get a fresh, clean plate for the cooked meat.
• Do not use marinade as a sauce for cooked meat.
• Avoid unpasteurized milk and unpasteurized juices.
• If a trip to a petting zoo or farm is planned, see the Enteric and Zoonotic Disease Prevention at Petting Zoos and Open Farms information in the Communicable Disease Control Manual for information on the risks associated with animal contact and what you can do to protect yourself and your children from infection.

Wash your hands:

• Before eating
• Before preparing food
• Immediately after handling raw meat or poultry, and before touching anything else
• After using the toilet or changing diapers
• After touching animals
• Make sure children, particularly those who handle pets or feed them raw pet treats, wash their hands carefully immediately afterwards, especially if they suck their thumbs or put their hands into their mouths. Wash their hands for them if they are too young.

• If your local drinking water provider has issued a Boil Water Notice for your community, take the advice seriously.
• Do not drink untreated surface water from a spring, stream, river, lake, pond or shallow well. Assume it is contaminated with animal feces.
• Boil or disinfect water from these sources if it is used for drinking, making ice cubes, washing uncooked fruits and vegetables, making baby formula, brushing teeth, and rinsing dentures or contact lenses.
• Boil for at least 1 minute at a rolling boil. At elevations above 2000 m (6562 ft) boil for at least 2 minutes, or
• Disinfect water if it is not cloudy using 1 drop of bleach per litre of water. Shake and allow to stand for 30 minutes before drinking. For more information, go to How To Disinfect Drinking Water - BC HealthFile #49b.