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E. coli

Escherichia coli, usually called E. coli, refers to a large group of bacteria that is commonly found in the intestines of humans and animals.

Most strains of E. coli are harmless; however, some strains, such as E. coli O157: H7, can make people sick, causing severe stomach cramps, diarrhea and vomiting. Serious complications of an E. coli O157:H7 infection can include kidney failure.

Causes

What causes infection with E. coli? How is it spread?

E. coli infections are generally caused by eating contaminated food, drinking contaminated water, or coming into direct contact with someone who is sick or with animals that carry the bacteria.

Infections can be caused by

  • improperly cooked beef;
  • raw fruits and uncooked vegetables, including sprouts;
  • untreated drinking water;
  • unpasteurized (raw) milk and (raw) milk products, including raw milk cheese;
  • unpasteurized apple juice/cider; and
  • direct contact with animals at petting zoos or farms.

Food can become contaminated with E. coli when animals are slaughtered or processed, even if precautions are taken. In processed or ground meat, the bacteria can be spread throughout the meat. Food can also be contaminated when it is handled by a person infected with E. coli, or from cross-contamination because of unsanitary food handling practices.

Raw fruits and vegetables can become contaminated with E. coli while in the field by improperly composted manure, contaminated water, wildlife or poor hygiene by farm workers.

E. coli infections can also spread easily from person to person.

Proper hygiene and safe food handling and preparation practices are key to preventing the spread of E. coli.

If you think you are infected with E. coli bacteria or any other foodborne illness, do not prepare food for other people. It's also a good idea to keep pets away from food storage and preparation areas.

Symptoms of E. coli infection usually start within about 3 to 4 days after exposure, but the incubation period can be as short as 1 day or as long as 10 days.

Symptoms

What are the symptoms of illness caused by E. coli?

Like other foodborne illnesses, the symptoms of E. coli infection mainly involve the gut. Symptoms may vary from person to person; however, they often include

  • severe stomach cramps;
  • diarrhea (often watery and may develop into bloody);
  • vomiting; and
  • fever (generally not very high - usually less than 38.5˚C/101˚F).

Around 5 to 10 per cent of those who get sick from E. coli O157:H7 overall and about 15 per cent of young children and the elderly develop hemolytic uremic syndrome (HUS), which can be fatal. Symptoms of HUS vary. Some people have seizures or strokes and some need blood transfusions and kidney dialysis. Others live with side effects such as permanent kidney damage.

How long do the symptoms last?

Most people recover fully within 5 to 10 days.

How long are people infectious?

Adults who are infected with E. coli bacteria are typically infectious for a week or less; however, in some cases children can be infectious for up to three weeks.

Risks

Are there certain foods that increase the risk of getting E. coli?

The following foods are commonly associated with E. coli:

  • beef - raw and undercooked, ground and whole cuts;
  • uunpasteurized apple juice or cider;
  • unpasteurized (raw) milk and raw milk products, such as raw milk cheese;
  • untreated drinking water; and
  • contaminated raw fruit and vegetables that are not cooked (including alfalfa and bean sprouts).

Are certain people more likely than others to get sick from E. coli?

Infections can occur among people of all ages, however symptoms are likely to be more severe among the very young and the elderly. Pregnant women and people with weakened immune systems are also at high risk of developing serious complications.

Is E. coli dangerous? Is it more dangerous for certain people?

Most people who become ill from E. coli bacteria will recover fully within 5 to 10 days.

Symptoms of E. coli infections are likely to be more severe among the very young and the elderly. Pregnant women and people with weakened immune systems are also at high risk of developing serious complications.

About 5 to 10 per cent of those who get sick develop hemolytic uremic syndrome (HUS), an unusual type of kidney failure and blood disorder, which can be fatal. Symptoms of HUS vary, depending on the person's health and the extent of the infection. Some people may have seizures or strokes and some may need blood transfusions and kidney dialysis. Others may live with side effects such as permanent kidney damage.

Those suffering from diarrhea should drink plenty of fluids to prevent dehydration - a possible serious health effect of a foodborne illness. The most helpful fluids for protecting against dehydration are oral rehydration fluids. These products are sold as pre-mixed fluids and are commonly found in drug stores. Other drinks that do not contain caffeine or alcohol can also help with mild dehydration; however, these drinks may not replace the nutrients and minerals lost during illness.

Young children, the elderly and people with other illnesses are at greatest risk for dehydration. Symptoms of dehydration in adults and children include a decrease in urination, a dry mouth and throat and dizziness upon standing. A dehydrated child may cry with few or no tears and be unusually sleepy or fussy. Severe dehydration can be serious and the ill person may require re-hydration in a hospital. If you think you or someone under your care is dehydrated, contact your healthcare provider.

Treatment

How is E. coli infection diagnosed and what is the treatment?

A diagnosis of E. coli infection can be confirmed through laboratory testing of stool (feces).

Generally, the disease must run its course. Treatment for those infected with E. coli includes drinking plenty of liquids to replace the body fluids lost through diarrhea and vomiting, and to avoid dehydration. The most helpful fluids for protecting against dehydration are oral rehydration fluids. These products are sold as pre-mixed fluids and are commonly found in drug stores. Other drinks that do not contain caffeine or alcohol can also help with mild dehydration; however, these drinks may not replace the nutrients and minerals lost during illness.

Young children, the elderly and people with other illnesses are at greatest risk for dehydration. Symptoms of dehydration in adults and children include a decrease in urination, a dry mouth and throat and dizziness upon standing. A dehydrated child may cry with few or no tears and be unusually sleepy or fussy. Severe dehydration can be serious and the ill person may require re-hydration in a hospital. If you think you or someone under your care is dehydrated, contact your healthcare provider.

Antibiotics are not used to treat the illness, as they may increase the risk of developing hemolytic uremic syndrome.

Prevention

How can E. coli infections be prevented?

Proper hygiene and safe food handling and preparation practices are key to preventing the spread of all foodborne illnesses, including E. coli.

Hand washing is one of the best ways to prevent the spread of foodborne illness.

Contaminated foods may look and smell normal. It is important to ensure that you thoroughly cook foods to destroy bacteria.

The following tips will help you reduce your risk of infection with E. coli or other food-borne illnesses:

  • Bacteria can grow in the danger zone between 4 °C and 60 °C (40 °F to 140 °F). Keep cold foods cold at or below 4 °C (40 °F) and keep hot foods hot at or above 60 °C (140 °F).
  • Place raw meat, poultry and seafood in containers on the bottom shelf of the refrigerator. Use containers that are large enough to prevent raw juices from dripping onto other food or touching other food.
  • Keep raw food away from other food while shopping, storing, preparing and serving foods.
  • Wash fresh fruits and vegetables before eating them, clean counters and cutting boards and wash your hands regularly.
  • Read labels and follow cooking and storage instructions for all foods. Make sure to check the “best before” date, and if you find something on the shelf that has expired, let the store know.
  • Use warm soapy water to clean knives, cutting boards, utensils, your hands and any surfaces that have come in contact with food, especially meat and fish.
  • Refrigerate or freeze perishable food within two hours of cooking.
  • Freeze or consume leftovers within four days of cooking. Always reheat leftovers until steaming hot before eating.
  • Keep refrigerators clean and at a temperature below 4 °C (40 °F). Install a thermometer in your fridge to be sure.

Will cooking destroy the bacteria?

Like many other harmful bacteria that could be in our food, E. coli bacteria are destroyed when food is cooked to a certain internal temperature. Use a digital food thermometer to measure the internal temperature of your food so that you are sure that it is cooked properly. You can’t tell by looking.

Cook your food to a safe internal temperature.

Food Temperature
Beef, veal and lamb (pieces and whole cuts)  - medium-rare 63°C (145°F)
Beef, veal and lamb (pieces and whole cuts)  - medium 71°C (160°F)
Beef, veal and lamb (pieces and whole cuts)  - well done 77°C (170°F)
Pork (pieces and whole cuts) 71°C (160°F)
Poultry (pieces) - chicken, turkey, duck 74°C (165°F)
Poultry (whole) - chicken, turkey, duck 85°C (185°F)
Ground meat and meat mixtures (burgers, sausages, meatballs, meatloaf, casseroles) - beef, veal, lamb and pork 71°C (160°F)
Ground meat and meat mixtures - poultry 74°C (165°F)
Egg dishes 74°C (165°F)
Others (hot dogs, stuffing and leftovers) 74°C (165°F)

Surveillance

Are E. coli outbreaks common in Canada?

In recent years, an average of about 440 cases of a certain type of E. coli infection was reported annually in Canada.

Outbreaks may occur in a community, a single province or multiple provinces, and not all outbreaks are reported to the national level. Between 2000 and 2004, there were 129 outbreaks and clusters of illness related to the same type of E. coli infection reported to PHAC, this number may not represent all of the outbreaks and clusters that have occurred in Canada during this period.

Does the Public Health Agency of Canada keep track of E. coli cases across the country?

Yes, the Public Health Agency of Canada works with the provinces and territories to track the number of certain E. coli cases across the country.

When people get sick and go to the doctor, those doctors in many cases take samples from the patients and send them to a local, provincial, territorial or federal lab for testing. Those labs test the samples to identify the organism causing illness and may conduct further testing to identify the genetic fingerprint of the bacteria.

Provincial/territorial labs report weekly to the National Enteric Surveillance Program the number of E. coli cases identified in their province. The laboratories may also then post the results of the test of the genetic fingerprint on PulseNet Canada, a national network that allows microbiologists to track and share genetic fingerprints for comparison across the country.

All labs then compare their results with those posted on PulseNet to find matches and identify outbreaks.

PulseNet Canada is coordinated by the Public Health Agency of Canada's National Microbiology Laboratory in Winnipeg.

The Canadian Notifiable Disease Surveillance System also tracks the total number of cases of E. coli infection each year and the age and sex of cases. This system is best for understanding if there are increases or decreases of illnesses over time.

The figure below shows the incidence rates of E. coli from 2003 to 2013 as reported through the Agency’s National Enteric Surveillance Program (NESP). The number of cases of E. coli O157 in 2012 was approximately half that reported in 2006. The data continue to show a downward trend.


Incidence rate of E. coli O157 VTEC and E. coli non-O157 serotypes (including untyped organisms) reported to PHAC through the National Enteric Surveillance Program (NESP), 2003 to 2013 (preliminary 2013 data)

Figure 1

Text equivalent

The table below lists the annual national totals and rates for E. coli O157 compared with other major organism groups as reported through the National Enteric Surveillance Program (NESP) from 2007 to 2013.


Annual National Totals and RatesFootnote (per 100,000) for Major Organism Groups Reported to NESP, 2007 to 2013Footnote *
Group 2007 2008 2009 2010 2011 2012 2013
Total Rate Total Rate Total Rate Total Rate Total Rate Total Rate Total Rate
Footnote
Rates calculated using the population estimates for Canada as of July 1st for years 2007 to 2013 as reported by Statistics Canada.
Footnote *
Preliminary numbers for 2013.
Footnote ¥
Only cases of E. coli O157 are included in this table, as E. coli non-O157 is not consistently reported by provinces.
Footnote £
Reporting of Listeria monocytogenes to NESP began in July 2010.
E. coli O157 Footnote ¥

934

2.84

661

1.99

529

1.57

405

1.19

481

1.40

486

1.40

470

1.34

Listeria Footnote £ - - - - - - - -

132

0.38

124

0.36

117

0.33

Salmonella

6419

19.52

6351

19.10

6084

18.09

7254

21.33

6806

19.82

6980

20.08

6270

17.83

Shigella

636

1.93

680

2.05

631

1.88

739

2.17

861

2.51

988

2.84

621

1.77

Protect yourself against food-borne illness by following safe food handling practices. For even more information about food safety, go to www.foodsafety.gc.caExternal Link.