Aw Nuts! E Coli on Walnuts

picture of walnuts


There has been an outbreak of e coli infections in four Canadian provinces.  The Canadian Food Inspection Agency has linked the infections to imported walnuts.  So far, one person has died.

E. Coli Walnut Recall Expanded.

Canadian Food Inspection Agency

What Is E. Coli?

Escherichia coli O157:H7, also known as E  coli, is a bacteria.  This bacteria occurs naturally in the intestines of cattle and other animals.  If humans become infected by this bacteria, it can result in serious illness.


An E  coli infection can show up within hours or as long as ten days after eating contaminated food.  Severe stomach cramps are the main symptom, but some people may experience bloody diarrhea.  Most people will recover in 10 to 15 days.  However, about 15% of the population may develop kidney failure that can become fatal.

Some people may never show signs of infection, but they can carry the bacteria and spread the infection to others.

How is the Bacteria Spread?

E coli is found in the intestines of cattle.  It can contaminate the surface of meats such as steaks or roasts, when the cow is slaughtered.  Highly processed meats or ground meats can have the bacteria spread throughout the meat.

So, if e coli is found in animals, how do other foods like raw fruits and vegetables, and walnuts get infected?  There are a few possibilities…

  • Contamination can occur in the field through the use of improperly composted manure.
  • The bacteria can  spread in contaminated water.
  • E coli is most ofter spread person-to-person.  Poor hygiene of workers processing/handling food can also spread the bacteria.

Four Ways to Stop E Coli:

  1. Sanitize:
    • Before handling foods, wash your hands with soap for at least 20 seconds.
    • Ensure counter-tops and utensils are clean and sanitized.
    • Wash raw fruits and vegetables under clean running water.
  2. Chill:
    • To slow bacteria growth, keep cold food below 4°C (40°F).
    • Freezing (below -18°C or 0°F) food can stop bacteria growth completely but it won’t kill the bacteria.  Only proper cooking can kill the bacteria.
  3. Separate:
    • Don’t cross contaminate!  Make sure the juices from raw meat do not touch any other foods.
    • If plates or utensils are used for raw meats, they should not be used with cooked or ready to eat foods.
  4. Cook:
    • Cooking meat to a safe internal temperature destroys e. coli bacteria.
    • The safe internal temperature depends on what you are cooking.  Refer to this chart.
    • You cannot judge the temperature by colour, look or feel!
    • Use a meat thermometer to check the internal temperature of your food.

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