1.1.1: Causes of Foodborne Illnesses

Causes of Foodborne Illnesses

Foodborne illnesses can be caused by:

• 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 (mold).

• Bacteria are present in many of the foods we eat and the body itself. Most bacteria are not harmful, 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 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. Roundworms (found in raw fish) are examples of parasites found in food.
• Protozoa are single-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 mold that grows on spoiled food, can be harmful and remain even after cutting or scraping the visible mold off the food.

Food Intoxication and Food Infection

Have you ever had the “24-hour flu”? 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. 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

There is also toxin-mediated infection which occurs when a biological pathogens are introduced to the body and after entering the digestive tract begin to produce a toxin. The toxin is what is responsible for the many symptoms associated with foodborne illness. Example: E.coli

Common Causes of Foodborne Illness

Bacteria:

While there are hundreds of different strains of bacteria that can cause illness in humans the Centers for Disease Control and Prevention (CDC) recognizes the top 5 types bacteria to cause illness in the United States as:

Table 1. Foodborne Illnesses

	Hepatitis A	Campylobacter Jejuni	Clostridium perfringens	E.coli	Listeria	Salmonella
Source	Raw/undercooked shellfish from contaminated waters Raw produce Contaminated drinking water  Uncooked foods  Cooked foods that are not reheated after contact with an infected food handler.	Unpasteurized (raw) milk Chicken Shellfish Turkey Contaminated water	Beef Poultry Gravies Food left for long periods in steam tables or at room temperature Time and/or temperature abused foods.	Contaminated food such as: Undercooked ground beef Unpasteurized (raw) milk and juice Soft cheeses made from raw milk Raw fruits/vegetables Contaminated water, including drinking untreated water and swimming in contaminated water. Animals and their environment, particularly cows, sheep, and goats. Feces of infected people.	Unpasteurized (raw) milk and dairy products. Soft cheese made with unpasteurized milk, such as queso fresco, feta, Brie, Camembert. Raw fruits and vegetables (such as sprouts). Ready-to-eat deli meats and hot dogs. Refrigerated pâtés or meat spreads. Refrigerated smoked seafood.	Food:  Vegetables Chicken, pork Fruits Nuts Eggs Beef Sprouts. Animals and their environments Reptiles (snakes, turtles, lizards) Amphibians (frogs) Birds (baby chicks) Pet food and treats.
Incubation Period	28 days average (ranges from 15 to 50 days)	2 to 5 days	6 to 24 hours	3 to 4 days for most people, can be 1 to 10 days	Usually 1 to 4 weeks Can be as long as 70 days	6 hours to 6 days
Symptoms	Diarrhea Dark urine or Light-colored stools Jaundice Fever Fatigue Nausea Joint pain Stomach pain Upset stomach Loss of appetite.	Diarrhea, cramps Fever Vomiting Diarrhea may be bloody.	Diarrhea Stomach cramps (no fever or vomiting)	Severe diarrhea that is often bloody Severe stomach pain and vomiting. Usually little or no fever is present. Symptoms of hemolytic uremic syndrome (HUS) : decreased urine production Dark or tea-colored urine, Losing pink color in cheeks and inside the lower eyelids.	Fever and diarrhea similar to other foodborne germ Symptoms in people with invasive listeriosis, meaning the bacteria has spread beyond the gut, include: For pregnant women: Fever Fatigue Muscle aches. Pregnant women may also have no symptoms but experience fetal death, pre-term labor, or infection of the newborn. For all others: Stiff neck Confusion Loss of balance Convulsions in addition to fever and muscle aches.	Diarrhea Fever Stomach cramps Vomiting
Duration	Less than 2 months. Some people can be ill for as long as 6 months.	~1 week	<24 hours In severe cases: 1-2 weeks.	5 to 10 days Most people will be better in 5 to 7 days. If HUS develops, it usually occurs after about 1 week.	Days to weeks	4 to 7 days
Prevention	Avoid eating raw oysters or other raw/undercooked shellfish. Wash hands frequently with soap and running water for at least 20 seconds after using the bathroom, after changing diapers, and before, during, and after preparing food. Vaccination	Drink pasteurized milk. Avoid raw milk/dairy. Do not drink untreated water.	Thoroughly cook foods, particularly meat, poultry, and gravies, to a safe internal temperature. Use a food thermometer Keep food hot after cooking (at 140˚ F or above)   Serve meat dishes hot, within 2 hours after cooking. Microwave leftovers thoroughly (to 165˚F or above). Refrigerate leftovers within two hours of preparation (at 40˚F or below). Divide large amounts of food, such as roasts or big pots of stew into shallow containers and refrigerate immediately. It is OK to put hot foods directly in the refrigerator.	Avoid high-risk foods such as: Unpasteurized milk or juice Undercooked ground beef Soft cheeses made from unpasteurized milk Sprouts Use a food thermometer Wash hands before, during, and after preparing food, after diapering infants, and after contact with cows, sheep, or goats, their food or treats, or their living environment.	Avoid raw (unpasteurized) milk, soft cheeses made with it, such as queso fresco. Eat cut melon right away or refrigerate it. People at higher risk should not eat the following foods: Refrigerated pâtés or meat spreads from a deli or meat counter or from the refrigerated section of a store Hot dogs, cold cuts, and deli meats, unless heated to an internal temperature of 165°F Refrigerated smoked seafood, unless canned or shelf-stable or cooked dish, such as a casserole Raw or lightly cooked sprouts of any kind	Avoid consumption of: Raw or lightly cooked eggs Undercooked ground beef or poultry Unpasteurized (raw) milk. Wash your hands after contact with animals, their food or treats, or their living environment.

"Adapted from: https://www.fda.gov/food/consumers/w...orne-illnesses" 

For more information on the above bacteria please visit the CDC website: here.

Viruses:

The majority of foodborne illnesses are caused by bacteria, however, there are several viruses that are common within the United States that can also cause illness. Examples of viruses are:

1. Norovirus
2. Hepatitis A

Please visit the link above to learn more about Norovirus. 

For more information on Norovirus please watch the following video from the CDC:  CDC Norovirus Prevention Video.

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

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 shellfish and ordered chicken strips with a house dipping sauce. The server assures the customer that there will be no shellfish used in the preparation of what they ordered. After eating the meal, the customer experiences tingling lips and hives. In follow up, the manager discovers that the oil used to fry the chicken strips had also been used to fry shrimp. 

This incident could have been prevented if cross contact was eliminated and different fryers were used to prepare menu items.

Allergic reactions occur when the body mistakenly reacts to a food that has been eaten as an intruder to the body. Allergens trigger the immune system whose job it is to eliminate harmful foreign bodies from circulation. This reaction results in an increase in white blood cells and the production of antibodies (Immunoglobulin E IgE). Allergic reactions can be experienced as mild symptoms such as a runny nose or itching, to more severe reactions such as anaphylaxis. 

Anaphylaxis involves multiple organ system and can decrease an individuals blood pressure and affect their ability to breathe making this a life-threatening reaction.

Top Food Allergies:

There are currently 8 food allergens recognized in the United States that are responsible for 90% of all allergic reactions. In April of 2021, the Food Allergy Safety, Treatment, Education, and Research (FASTER) Act was signed into law by President Joe Biden making sesame the 9th major food allergen. Starting January 1, 2023 foods produced for sale in the United States will be required to identify food sources of sesame on the labels.

Top allergens:

1. Peanuts
2. Tree nuts
3. Milk
4. Soy
5. Wheat
6. Eggs
7. Fish
8. Shellfish
9. Sesame

Source: https://www.fda.gov/food/food-labeli...nited%20States.

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