Cause and Prevention of Foodborne Illness


To provide current information on the following:

  • The causes of foodborne illness.
  • Food safety practices that reduce/prevent the risk of foodborne illness.


A recent study commissioned by the American Meat Institute and conducted in April, 1996, by Yankelovich Partners, Inc. accessed on a poll of 1,002 American adults found that:

  • Americans lack an understanding of the potential sources of foodborne illness–compared with 98% who knew that harmful bacteria can be present on meat and poultry products, only three in four consumers correctly made the link to dairy products (74.1% and eggs (73.5%) while only two in five (43.1%) made the connection to fruits and vegetables.
  • Most consumers underestimate the potential for foodborne illness in the home– -when asked what percentage of foodborne illness cases are caused by improper food handling in homes and restaurants, over half of the respondents (52.6%) estimated under 25% of the cases. Another one fourth of the respondents (27.5%) put the number of cases at “25 to 74″ percent, which is still far below the estimates of the Federal Centers for Disease Control and Prevention (CDC) that as much as 97% of foodborne illness can be linked to improper handling in the home or restaurants.
  • The public lacks basic knowledge about key food handling practices-when it comes to cooking meat products, the survey found that two-thirds of respondents didn’t know that ground beef needs to reach 155° F to kill harmful bacteria (Food Protection Report, October, 1996 p2A).

In 1997, Audits International, a foodservice consulting firm, conducted a survey of 100 households in 81 American cities. Their auditors asked friends if they would be willing to invite them to dinner so their meal preparation practices could be evaluated. The evaluation was based on the same standards included in the 1997 FDA Model Food Code and used in inspections of foodservice establishments. Ninety-six percent (96%) of the households inspected were “cited” for critical violations. The most frequent violations which could result in cross contamination including failure to wash, rinse and sanitize cutting boards between uses, improper handwashing, failure to use thermometers and misuse of cloths, sponges or towels (Food Protection Report, March, 1998). Recently, Audits International conducted a follow-up study. They conducted a telephone survey of more than 100 participants. Thirty-five of the respondents had participated in the 1997 study. All participants agreed they had an increased awareness about food safety in general based on increased media attention. However, the 1997 survey participants who had received a thorough exit interview at the conclusion of their audit that included suggestions for improvement indicated they had greatly improved their food safety practices. Richard W. Daniels, President of Audits International stated the results of the latest survey support our belief that education and motivation are the key to getting people to make the necessary food safety improvements. (Audits International, February 1999).

This survey as well as previous survey findings indicate American consumers lack basic knowledge about safe food handling principles. Food safety educators and researchers agree that education is the key to reducing the risk of foodborne illness. Part of this educational effort includes helping consumers of all ages to understand the major causes of foodborne illness and to show that simple, “low-tech” safe food handling practices can reduce the risk of foodborne illness at home.

Causes of Foodborne Illness in the Foodservice Environment

A Scientific Status Summary on Foodborne Illness: Role of Home Food Handling Practices in the April, 1995 issue of Food Technology cites the research done by Frank Bryan in 1988. Dr. Bryan reviewed the food handling errors that led to foodborne illness outbreaks reported to the Centers for Disease Control (CDC) between 1961 and 1982 and divided them into the following categories:

1. Failure to properly cool food.
2. Failure to thoroughly heat or cook food.
3. Infected employees who practice poor personal hygiene at home and at the workplace.
4. Foods prepared a day or more before they are served.
5. Raw, contaminated ingredients incorporated into foods that receive no further cooking.
6. Foods allowed to remain at bacteria-incubation temperatures.
7. Failure to reheat cooked foods to temperatures that kill bacteria.
8. Cross-contamination of cooked foods with raw foods, or by employees who mishandle foods, or through improperly cleaned equipment.

The factors listed above can be divided into the following broad categories:

1. Contaminated Ingredients
2. Temperature Control
3. Personal Hygiene
4. Cross Contamination
5. Sanitation

Note: In this section we refer to these categories as the “Fatal Five.”

Food Safety Practices that Prevent/Reduce Foodborne Illness

The major causes of foodborne illness or the “Fatal Five” are outlined below. Food handling practices that prevent or reduce the risk of foodborne illness are listed after each of the fatal five.

1. Contaminated Ingredients

Food may be contaminated by chemical, physical or microbiological sources. It should be assumed that raw potentially hazardous foods-i.e., meats, fish, poultry eggs are contaminated with pathogenic bacteria and should never be eaten raw or undercooked.

Examples include:

  • Raw fish (sushi) and shell fish
  • Foods containing raw egg such as homemade mayonnaise, Caesar salad dressing, ice cream and egg nog
  • Raw meat (Steak Tar Tar)

Prevention Practices

  • Shopping
    Check packaged food for tears and canned goods for bulges or dents Purchase only packaged food that appears to be in good condition.
  • Storing
    • Store all food items away from household cleaning supplies
    • Label containers of household cleaners or detergents so they are not mistaken for food items. For example, cornstarch and some laundry detergents are similar in texture.
    • Protect dry foods (rice, flour, pasta, cereals) from insects and rodents that often carry harmful bacteria by storing in airtight containers in a cool, dry, place.
    • In the refrigerator, always place raw food items on the bottom shelves to prevent their juices from dripping onto cooked food items.
  • Preparation/Service
    • Wash fresh fruits and vegetables with plain water.
    • Do not use gray enamelware, galvanized, brass or copper containers with acidic foods like lemonade, strawberries, tomato products and salad dressing for cooking, serving or storage.
    • Use metal containers and metallic items only for their intended uses (for example do not use refrigerator shelves as grills).
    • Clean can openers often to prevent small slivers of metal from cans from falling into food.

2. Temperature Control

Failure to cool potentially hazardous foods quickly and failure to cook them thoroughly are major causes of foodborne illness. It is vital to keep foods, especially potentially hazardous foods out of the Temperature Danger Zone. To insure that foods are cooled, cooked, held at hot or cold temperatures that severely limit bacterial growth, some type of food temperature measuring device must be used. The most commonly used is the dial face, metal stem, bimetallic thermometer.
A metal stem bimetallic thermometer is an important tool for keeping track of food temperatures.

Prevention Practices

  • Shopping
    • Pick up foods that should be kept cold last.
    • Buy eggs only from a refrigerated case.
    • In hot weather, take along cooler to keep foods cold.
    • Buy products labeled “Keep Refrigerated” only from a refrigerated case.
  • Storage
    • Refrigerate or freeze cold food right away.
    • Maintain refrigerator temperature at 41°F. Place a thermometer in the rear portion of the refrigerator and check at least once a day.
  • Preparation/Service
    • Defrost frozen foods in the refrigerator, NEVER on the kitchen counter. Food defrosts from the outside towards the center, and the outside may be at room temperature for an extended period of time, while the center is still frozen. The outside of the potentially hazardous food is at optimum temperature for rapid bacterial growth.
    • Interrupted and/or partial cooking of potentially hazardous foods provides optimum conditions for bacterial growth, therefore it should not be done.
    • Using a bimetallic thermometer is the only method to insure that potentially hazardous foods are thoroughly cooked. Visual appearances, or relying on oven temperatures and time do not ensure that the food product is thoroughly cooked. The ONLY way to assure that a food product is thoroughly cooked is to take the temperature of the food. However, visual observations may serve as the first cue that a food may be sufficiently cooked. Some visual cues include:
      • hamburgers should be brown all the way through and their juices translucent. (160°F)
      • fish should be white and flaky.
      • chicken and pork should be white and their juices run clear. (180°F)
      • any batters (i.e., cookie, cake, brownie) containing raw egg should not be eaten. The eggs may be contaminated with Salmonella bacteria. Thorough cooking of the food item containing the raw egg will kill any harmful bacteria.
      • Keep hot foods hot (140°F+) and cold foods cold (41°F or lower) during buffet service

    Pre-prepared and Leftover Foods

    • Immediately after a meal, within two hours, divide foods into smaller amounts and place in the refrigerator.
    • Always remove stuffing from meats and poultry and store separately
    • Divide large pieces of meat or poultry into smaller pieces.
    • To cool a large amount of soup, stew, chili or other like food, place the container of food in a sink which contains cold water and ice. The greater the proportion of ice to water, the quicker the cool down, stirring will shorten the cooling time. The container of food may then be covered and placed in the refrigerator.

3. Cross Contamination

Cross contamination is the transfer of harmful bacteria from one food item to another by means of a nonfood surface, i.e., utensil, counter top, cutting board, mixing bowl, human hands, humans wearing single-use plastic gloves.

Bacteria can survive in kitchen sponges, dishtowels and dishcloths and be “transferred” to utensils and equipment used in food preparation. The level of bacterial contamination in household sponges was investigated in a study conducted in 1994 by University of Arizona, environmental biologist Gerba funded by the 3M Corporation manufacturers of O-Cello sponges. Teams of college students in the Chicago, Illinois area went door to door offering to trade new sponges for dirty household sponges and dishrags. Of the 150 he tested, Gerba found that 809% contained bacteria, about 15 different kinds, that could be harmful to susceptible individuals. Twenty percent (20%) of the rags and 12% of the sponges also showed a presence of salmonella. (Dairy Food Environmental Sanitation, January, 1997)

Prevention Practices

  • Shopping
    • Put raw meat, fish and poultry in plastic bags to prevent their juices from dripping onto other foods.
  • Refrigerator Storage
    • In the refrigerator, store raw meats, fish, poultry below cooked and ready-to-eat raw foods to prevent their juices dripping onto other food items.
    • Store raw and cooked foods in separate areas.
  • Preparation
    • Put food in a plastic bag or dish on the lowest shelf in the refrigerator to prevent juices from dripping onto other foods.
    • Use utensils to serve food items that are already cooked.
    • Use a clean serving plate, not the plate that held the raw meat to serve cooked meat.
    • Wash, rinse and sanitize cutting boards and knives after cutting raw, meat, fish or poultry.
    • Use paper towels to wipe up meat, fish, or poultry spills.
    • Kitchen dishtowels, cloths and sponges should not be used to wipe up food spills from the floor or clean hands and faces.
    • Limit hand contact with tableware
    • Handle glasses or cups by the bottom or handles – don’t touch the rim
    • Pick up and place utensils by their handles
    • Avoid touching the rims of bowls, dishes, plates.

4. Personal Hygiene

People are the key to preventing/reducing the risk of foodborne illness. People can be carriers of disease causing microorganisms and not show symptoms of illness, but may pass on the illness to other people. One half of all healthy people carry a type of staphylococcus either without symptoms or in a pimple, acne or skin wound.

In the summer of 1997, several incidents of Hepatitis A were attributed to cooked bakery products that were mishandled by infected foodservice workers. In the case of Hepatitis A, an individual can be carrying and “shedding” the viruses for 15 to 50 days before they have any of the symptoms of the illness.
Hands, which can never be totally free of bacteria, are in constant contact with cooked and uncooked food items. Limiting hand contact with all food items is one of the first lines of defense in reducing foodborne illness. The 1999 FDA Food Code and many state and local food codes require that employees in food establishments can not touch ready-to-eat food with their bare hands. They can use utensils; deli paper, spatulas, tongs or single use plastic gloves. Single-use plastic gloves can only be used for one task. A new pair of gloves must be used for the next tasks. They should not be used for other purposes.

Hands must be washed frequently, for at least 20 seconds with warm water and soap. They should always be washed after using the restroom, eating, before starting food preparation, after preparing a raw potentially hazardous food and preparing a food item that is eaten raw, picking up objects from the floor, handling a pet, taking out the trash/garbage, coughing, sneezing, touching any part of the body, clearing tables and handling dirty dishes.

The Bayer Pharmaceutical Division and the Society for Microbiology funded a study, whose results were announced at the September 1996 meeting of the American Society for Microbiology. The results of the study show that the percentage of people who say they wash their hands after using the restroom is higher than the percentage who actually do. Researchers telephoned over 1,000 adults. Ninety-four percent (94%) reported always washing their hands after using a public restroom. The researchers than observed adults in public restrooms in five major cities during a weekend in August. They found that only 68% really did wash their hands. Women were more likely to wash than men in all cities. In announcing the results of the study, the research sponsors launched “Operation Clean Hands”, a campaign to educate Americans about the health risks associated with poor hand washing habits. More information and educational resource material is available by calling 1-888-97-BAYER (Food Protection Report, October, 1996).

Prevention Practices

Preparation and Service

  • Wash hands often with warm water and soap at least twenty seconds
  • After using the restroom
  • Before starting food preparation
  • After touching/working with a raw potentially hazardous food (meat, fish, poultry)
  • Picking up objects from the floor
  • Handling a pet
  • Taking out the garbage/trash
  • Coughing, sneezing
  • Touching any part of the body
  • Clearing tables and handling dirty dishes, pots and pans and cooking utensils
  • After using household cleaners
  • During food preparation as needed
  • Limit bare hand contact with ready to eat foods by using single-use plastic gloves, tongs, deli paper
  • Wear clean aprons, clothing during food preparation
  • Limit hand contact with parts of plates and utensils that come in contact with an individual’s mouth (see section on cross-contamination)

5. Sanitation

Sanitation practices impact many of the other causes of foodborne illness. For example, if the knife and cutting board that has been used to cut up raw chicken is not washed, rinsed and sanitized before being used to cut up carrots for a salad, cross contamination can occur.

Washing with hot water (not less than 110° F) and detergent and rinsing with hot water to remove soil and food particles and detergent residue must take place in order for sanitizing to be effective. Sanitizing is defined by FDA as “a process which reduces the presence of microorganisms to safe levels”. It is not a substitute for cleaning.

Heat and chemicals are the two types of commonly used sanitizers. Heat may be used by immersing cleaned equipment and utensils in water that maintains a temperature of 165°F (74° C) or above for at least 10 seconds after they are washed and rinsed. The water should be changed often due to loss of temperature and build up of residues, etc. If food preparation equipment and tableware are washed in a dishwasher, the water temperature should be at least 165°F. For safety reasons, the water temperature should never be above 194° F.

There are a wide variety of chemical sanitizers available to the food industry. Hypchiorites deodorize and sanitize, are colorless and nonstaining, are easy to use, inexpensive, nontoxic to humans when used at recommended concentrations and readily available for use in foods and nutrition labs. Sodium hypochlorite, known as household chlorine bleach contains between 1-15% available chlorine. Hypchlorites release hypochlorous acid in solution, It is the hypochlorous acid that destroys microorganisms. The effectiveness of the sanitizing solution of chlorine bleach and water id directly related to the water temperature and pH of the sanitizing solutions. They are not affected by hard water and do not leave a residue.

The cleaned items should be soaked in the chlorine sanitizing solution for at least 10 seconds. The solution should be tested periodically using test strips that measure the concentration of the sanitizing solution. The test strips may be purchased from restaurant supply houses. Caution: Chlorine bleach is considered a hazardous material. Read the label concerning precautions for use.

Prevention Practices

Cold and Dry Storage

  • All food storage areas-i.e., refrigerators, cupboards should be kept clean.
  • Food items in dry storage should be kept in airtight containers to prevent access by rodents and insects. Rodents and insects carry harmful bacteria that can contaminate food.

Preparation and Service

  • Use paper towels to wipe up potentially hazardous food spills.
  • Wash, rinse and sanitize cutting boards, utensils and countertops after use in preparation of raw potentially hazardous foods. 


  • All food contact surfaces including pots and pans, utensils, equipment, counter tops, tableware (dishes and silverware) and glassware should be clean and sanitized at some point(s) during the preparation, service and clean-up.
  • If a three bin sink is not available, create a third sink by placing a clean plastic dishpan on the counter and fill with the sanitizing solution.
  • All sanitized equipment should be air dried.
  • Wiping cloths, when not in use, should be stored in a solution of 1 teaspoon of chlorine bleach to 1 gallon of water.