Food Safety, Sanitation, and Personal Hygiene

3 Causes of Foodborne Illnesses

There are many myths about foodborne illness and food poisoning. Table 1 dispels some common misconceptions about food poisoning.

Table 1. Food poisoning myths
Myth Fact
1. A food with enough pathogens to make you sick will look, smell, or taste bad. 1. A food with enough pathogens to make you sick may look, smell, or taste good.
2. Really fresh food cannot make people sick. 2. Really fresh food can cause food poisoning if it is not properly handled.
3. Only dirty kitchens can make people sick. 3. Even clean kitchens can make people sick.
4. Properly cooked food can never cause food poisoning. 4. Food poisoning can occur even when foods are properly cooked.

Foodborne illnesses can be caused by any of:

  • Contaminants
  • Improper food handling practices
  • Food allergies

Understanding each of these is critical in ensuring that food safety is maintained.[1]

Food contaminants can be:

  • Chemical, such as cleaning agents or pesticides
  • Physical, such as hair, bandages, or glass
  • Biological, such as pathogens and microbes introduced from infected workers, unsanitary work surfaces, or contaminated water

Biological causes of foodborne illness

Biological contaminants are by far the greatest cause of illness. Many of the risks associated with biological contaminants can be controlled or removed by effective food handling practices, so it is critical that the safe food handling and prevention procedures outline in the rest of the book be followed.

Microbes are all around us. They are living things, often too small to be seen without a microscope. Many microbes are beneficial, but some can cause illness or even death. These harmful microbes are called pathogens. Five types of microbes include bacteria, viruses, parasites, protozoa, and fungi.

  • Bacteria are present in many of the foods we eat and the body itself. Most bacteria are not harmful, and some are even very beneficial to people, but some types of bacteria are pathogenic and can cause illness. Campylobacter, E.coli, Listeria, and Salmonella are examples of pathogenic bacteria. Foods that contain these bacteria must be handled correctly and cooked appropriately.
  • Viruses frequently cause illness, and are found in food, but do not grow or multiply in food. Most foodborne illness caused by viruses happens because the person handling the food has transmitted to the virus to the food through improper food handling or poor sanitation. Hepatitis A and Norovirus are examples of viruses that are responsible for foodborne illness.
  • Parasites live in or on animals and people and cause illness when the food infected with the parasite is not cooked to a temperature high enough or frozen to a temperature cold enough to kill the parasite. Trichinella (found in pork and some game meats) and roundworms (found in raw fish) are examples of parasites found in food.
  • Protozoa are one celled animals that may be found in water. Use of water from unsafe sources can lead to illness. Giardia lamblia is an example of protozoa that may be found in water from rivers, lakes, streams and shallow wells. Food washed in water containing Giardia lamblia that is served without any further cooking (such as salad greens) can cause illness.
  • Fungi grow on decaying organic matter. Many fungi are harmless or beneficial, but some, such as mould that grows on spoiled food, can be harmful and remain even after cutting or scraping the visible mould off the food.

Food Intoxication and Food Infection

Have you ever had the “24-hour flu”? Probably not, because there’s no such thing. Many people who think they have the 24-hour flu have had a foodborne illness caused by some type of pathogen. A rapid reaction is normally caused by a food intoxication. A slower reaction is normally caused by a food infection. Here’s how to tell the difference between the two:

  • Food intoxication occurs when bacteria grow in food and produce a waste product called a toxin (poison).  When the food is eaten, the toxins are immediately introduced into the body, causing a rapid reaction.  Example:  Staphylococcus
  • Food infection occurs when food contains living pathogens that grow in the human intestinal tract after the food is eaten.  Because the bacteria continue to multiply in the body and cause infection, the reaction will be slower.  Example: Salmonella

Improper Food Handling Practices

The top 10 causes of foodborne illness are the following:

  1. Improper cooling
  2. Advance preparation
  3. Infected person
  4. Inadequate reheating for hot holding
  5. Improper hot holding
  6. Contaminated raw food or ingredient
  7. Unsafe source
  8. Use of leftovers
  9. Cross-contamination
  10. Inadequate cooking

We will be looking at this top 10 list in greater detail later in the book.

Food Allergies

Food allergies are specific to individuals, but can be life threatening, and can be prevented by a thorough understanding of the allergy issue, knowledge of ingredients used in the preparation of foods, including pre-prepared foods, and care in ensuring separate cooking utensils, cookware, and food preparation surfaces. Oftentimes, the smallest oversights can have serious consequences, as indicated in the example below:

A customer has indicated they have an allergy to MSG and ordered chicken strips with a sweet and sour sauce.  The server tells them that the restaurant doesn’t add MSG to any of its food normally, so the order should be fine.  After eating the sauce, the customer experiences tingling lips and hives.  In follow up, the manager discovers that the pre-prepared sweet and sour sauce served with the chicken strips contains MSG on the list of ingredients.

This incident could have been prevented if the server was aware of all of the ingredients used in the dish.

Find more information foodborne illness and their causes and symptoms on the FOODSAFE Foodborne Illness Chart [PDF].

  1. For more information on foodborne illnesses, outbreaks, and important news bulletins, consult the BC Centre for Disease Control website.


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Food Safety, Sanitation, and Personal Hygiene Copyright © 2015 by The BC Cook Articulation Committee is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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