Food Safety: Understanding foodborne
illness
Most people have been affected by what’s commonly known as food poisoning at some point.
Understanding the causes of foodborne illnesses is an important step to help prevent them.
What are foodborne illnesses?
Foodborne illnesses are caused by eating food contaminated with harmful microorganisms. The majority
of cases are caused by bacteria. Viruses, parasites, moulds and toxins (chemicals) can also cause
foodborne illness.
Foods can become contaminated when food is not handled safely. Some common mistakes include not
chilling or cooking foods properly, cross-contamination of cooked with raw foods, and unclean cooking
surfaces, utensils, dishes or hands. One of the most common mistakes is leaving foods in the “danger
zone” where bacteria grow quickly, between 4°C (40°F) and 60°C (140°F).
What are the symptoms?
The symptoms of foodborne illnesses can range from mild to very serious. They may include:
stomach cramps
nausea
diarrhea
vomiting
fever
headaches
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You may feel the affects of food poisoning right after eating a contaminated food or you may not feel sick
until a few days or a month later. In most cases, the symptoms don’t last very long. Often people don’t
even realize they have a foodborne illness because it can feel like the flu.
Foodborne illnesses, however, can be very serious and even fatal. Some people are more likely to
become seriously ill than others. These include infants and young children, pregnant women, senior
citizens and people with weakened immune systems, such as those with cancer, liver disease and AIDS.
In some cases, foodborne illness can cause long term problems such as kidney damage, arthritis or
heart problems.
Which bacteria are to blame?
Scientists have identified hundreds of different foodborne illnesses. Some are rare, while others are
much more common. The following five bacteria are common causes of food poisoning. Click on the
links below to learn more about the common food sources, symptoms and prevention of each of these:
Bacteria
Common sources
Symptoms may include
Prevention Tips
Campylobacter Raw poultry, unpasteurized (raw)
Fever, headache and muscle pain, Keep raw meat and poultry separate from
jejuni
milk and untreated water. (Note:
followed by diarrhea (often
ready-to-eat foods. Cook foods to a safe
dogs, cats and farm animals can
bloody), stomach pain, cramps,
internal temperature. Drink only
also carry this bacteria.)
nausea and vomiting.
pasteurized milk and use a safe water
supply.
Clostridium
Improperly prepared home-canned, Nausea, vomiting, fatigue,
Never eat food from cans that are dented,
botulinum
low-acid foods (e.g. corn,
dizziness, headache, double
leaking or bulging. Be sure to follow proper
mushrooms, spaghetti sauce,
vision, and dryness in the throat
canning processes when canning foods at
E.coli
salmon, garlic in oil). Honey may alsoand nose. In some cases, these
home. Refrigerate all foods that are
be contaminated with C. botulinum. may lead to respiratory failure,
labelled “keep refrigerated”. Do not feed
paralysis and even death.
honey to children under one year.
Raw or undercooked meats
Stomach cramps, diarrhea
Keep your hands, food preparation
(especially ground meats), raw
(sometimes bloody) and fever.
surfaces and utensils clean. Avoid cross-
vegetables and fruit. Untreated waterSome may develop Hemolytic
contamination. Rinse raw vegetables and
and unpasteurized (raw) milk and
Uremic Syndrome, an unusual type fruit well. Store and cook foods properly.
unpasteurized apple juice or cider.
of kidney failure and blood
Updated: 2016-10-09 | Page 2 of 4
disorder, which can result in death.
Listeria
Non-dried processed meats (hot
Vomiting, nausea, fever,
Thoroughly cook meat, poultry and fish.
dogs and deli meats), unpasteurized headache, cramps, diarrhea and
Heat hot dogs to steaming hot. Keep
(raw) milk and milk products (soft
constipation. Some may develop
leftovers in the refrigerator for a maximum
cheeses), raw vegetables, raw or
meningitis encephalitis (a brain
of four days and reheat thoroughly before
undercooked meat, poultry or fish.
infection) and/or septicaemia
eating. Wash fresh vegetables and fruit
(blood poisoning) which can result well. Avoid unpasteurized milk and milk
in death.
Salmonella
products.
Raw or undercooked poultry, meat, Stomach cramps, diarrhea, fever, Cook foods to a safe internal temperature.
fish, and eggs, raw vegetables and vomiting and nausea. Some may
Use a food thermometer to be sure. Use
fruit, unpasteurized (raw) milk and
pasteurized egg products instead of raw
experience chronic symptoms,
milk products (soft cheeses), sauces such as reactive arthritis (Reiter's eggs, in foods such as eggnog,
and salad dressings, peanut butter, Syndrome) three to four weeks
mayonnaise, salad dressing, ice cream and
cocoa and chocolate.
mousses. Wash raw vegetables and fruit
later.
well.
What can you do?
Harmful bacteria can infect our food at any point in the food chain, from the farm to when it reaches our
plate. The good news is - most cases can be prevented by using safe food handling practices and using
a food thermometer to check that your food is cooked properly.
Remember, you usually can’t tell whether foods are contaminated by the way they look, smell, or taste.
So the safe rule of thumb is - When in doubt, throw it out!
If you think you have a foodborne illness, report it to your doctor or health department.
Learn more about
Food Safety – True or False
Causes of Food Borne Illness, Canadian Food Inspection Agency.
Food Recalls and Allergy Alerts, Canadian Food Inspection Agency
Food Safety Tips, Canadian Partnership for Consumer Food Safety Education.
Updated: 2016-10-09 | Page 3 of 4
This content from www.eatrightontario.ca is Copyright © Dietitians of Canada 2015, unless otherwise indicated.
The content is not meant to replace advice from your medical doctor or counselling from a Registered Dietitian.
It is intended for educational purposes only. Dietitians of Canada acknowledges the financial support of EatRight
Ontario by the Ontario government. The views expressed do not necessarily reflect those of the province.
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