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Common Foodborne Pathogens/Illnesses
A foodborne illness is any illness resulting from the consumption of food contaminated with pathogenic microorganisms; usually caused by improper food processing, handling, preparation, or storage. Good hygiene practices before, during, and after food preparation can reduce the chances of contracting an illness.
10 Most Important Factors Contributing to Foodborne Illnesses in the United States:
- Improper cooling
- Lapse of 12 or more hours between preparation and eating
- Infected persons handling foods
- Inadequate reheating
- Improper hot holding
- Contaminated raw food or ingredients
- Foods from unsafe sources
- Improper cleaning of equipment and utensils
- Cross contamination from raw to cooked foods
- Inadequate cooking
(Source: Virginia Cooperative Extension)
For a complete list of foodborne illnesses, visit the Center for Disease Control and Prevention’s "A-Z Index for Foodborne Illnesses" at www.cdc.gov/foodsafety/diseases/index.html.
Most Common Foodborne Illnesses
|Campylobacteriosis||Infectious diarrheal disease|
|Raw or undercooked poultry; unpasteurized milk; contaminated water|
|Common Symptoms: Diarrhea, cramping, abdominal pain, fever, possible nausea and vomiting||Prevention Tips – What You Can Do: Observe proper handwashing techniques; cook meat to a safe temperature; use only pasteurized dairy products|
|C. perfringens Food Poisoning|| |
Common gastrointestinal illness
|Clostridium perfringens||Raw or undercooked beef and poultry; gravies and other pre-cooked foods that are not properly handled|
|Common Symptoms: Diarrhea, abdominal cramps||Prevention Tips – What You Can Do: Cook foods to a safe temperature; follow proper heating/cooling procedures for food|
|Norovirus Food Poisoning||Highly contagious virus that causes acute gastroenteritis||Norovirus||Food and water contaminated with the feces of infected humans (commonly, leafy greens, fresh fruit, and shellfish)|
|Common Symptoms: Abdominal pain, nausea, diarrhea, vomiting||Prevention Tips – What You Can Do: Observe proper handwashing techniques; wash raw produce before consumption; cook seafood thoroughly; do not prepare food if you exhibit norovirus symptoms|
|Salmonellosis||Gastrointestinal infection||Salmonella bacteria||Food contaminated with the feces of infected animals; contamination from an infected food handler not following proper handwashing procedures|
|Common Symptoms: Diarrhea, fever, abdominal cramps||Prevention Tips – What You Can Do: Observe proper handwashing techniques; cook eggs and meat to a safe temperature; use only pasteurized dairy products; thoroughly clean all prep utensils/areas after exposure to uncooked foods; do not prepare food if you exhibit salmonellosis symptoms|
|Staphylococcal Food Poisoning||Gastrointestinal illness||Staphylococcus aureus||Unpasteurized dairy products; contamination from an infected food handler not following proper handwashing procedures|
|Common Symptoms: Nausea, vomiting, stomach cramps, diarrhea||Prevention Tips – What You Can Do: Observe proper handwashing techniques; follow proper heating/cooling procedures for food; do not prepare food if you have a nose or eye infection or wounds/skin infections on hands/wrists|
Other Foodborne Illnesses
|Botulism||Very rare, serious paralytic illness||Clostridium botulinum, Clostridium butyricum, Clostridium baratii||Improperly canned or preserved foods (often those with low acid content)|
|Common Symptoms: Double or blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, muscle weakness||Prevention Tips – What You Can Do: Discard bulging cans or foul-smelling preserved foods|
|Cryptosporidiosis||Parasitic infection||Cryptosporidium||Food and water contaminated with the feces of infected humans or animals|
|Common Symptoms: Diarrhea, abdominal cramps, dehydration, nausea, vomiting, fever, weight loss||Prevention Tips – What You Can Do: Observe proper hand-washing techniques; wash raw produce before consumption; use only pasteurized milk, juice, and cider|
|Cyclosporiasis||Gastrointestinal illness||Cyclospora cayetanensis||Food and water contaminated with the feces of infected humans or animals|
|Common Symptoms: Diarrhea, loss of appetite/weight, cramping, bloating, gas, nausea, fatigue||Prevention Tips – What You Can Do: Observe proper hand-washing techniques; wash raw produce before consumption; use only pasteurized milk, juice, and cider|
|Diarrheagenic E. coli||Infectious diarrheal disease||Escherichia coli||Unpasteurized milk, apple cider, and cheese; any food or water contaminated with the feces of infected humans or animals|
|Common Symptoms: Severe stomach cramps, diarrhea, vomiting||Prevention Tips – What You Can Do: Observe proper hand-washing techniques; cook foods to a safe temperature; wash raw produce before consumption; use only pasteurized milk, juice, and cider|
|Giardiasis||Parasitic infection||Giardia intestinalis, Giardia lamblia, Giardia duodenalis||Food and water contaminated with the feces of infected humans or animals|
|Common Symptoms: Chronic diarrhea, gas, greasy stools, abdominal cramps, nausea, vomiting, dehydration||Prevention Tips – What You Can Do: Observe proper handwashing techniques; cook foods to a safe temperature; wash raw produce before consumption; use only pasteurized milk, juice, and cider|
|Listeriosis||Serious digestive infection||Listeria monocytogenes||Variety of foods of animal origin (such as meat and dairy products), including raw, undercooked & unpasteurized foods and processed meats|
|Common Symptoms: Fever, muscle aches; possible diarrhea, headache, stiff neck, confusion, loss of balance, convulsions||Prevention Tips – What You Can Do: Cook meat to a safe temperate; wash raw produce before consumption; thoroughly clean all prep utensils/areas after handling uncooked foods; follow food storage time guidelines; use only pasteurized milk|
|Taeniasis (Tapeworms)||Parasitic infection||Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm)||Raw or undercooked beef or pork|
|Common Symptoms: Mild abdominal symptoms||Prevention Tips – What You Can Do: Cook meat to a safe temperature|
|Raw or undercooked meat (esp. pork, lamb & venison)|
|Common Symptoms: Flulike symptoms; severe toxoplasmosis can cause damage to the brain, eyes, or other organs||Prevention Tips – What You Can Do: Observe proper handwashing techniques; cook meat to a safe temperature; thoroughly clean all prep utensils/areas after handling raw meat|
|Trichinellosis (Trichinosis)||Parasitic infection||Trichinella||Raw or undercooked meat (esp. pork)|
|Common Symptoms: Initial symptoms: nausea, diarrhea, vomiting, abdominal pain; Classic symptoms: muscle pain, fever, facial swelling, weakness, headache, rash, cough||Prevention Tips – What You Can Do: Observe proper handwashing techniques; cook meat to a safe temperature; thoroughly clean all prep utensils/areas after handling raw meat|
|Gastrointestinal infection (most often affecting children)|
|Raw or undercooked meat (esp. pork)|
|Common Symptoms: Fever, abdominal pain, diarrhea||Prevention Tips – What You Can Do: Observe proper handwashing techniques; cook meat to a safe temperature; thoroughly clean all prep utensils/areas after handling raw meat; use only pasteurized dairy products|
Food spoilage can be caused by spoilage bacteria, microorganisms that cause food to deteriorate. Due to unpleasant flavors and odors, most people will not eat spoiled food – although even if they did, they would probably not get sick. This is an important point of differentiation between food spoilage bacteria and pathogenic bacteria (as described in the above table), which can cause foods to be dangerous to eat while appearing fine. However, some spoilage-accelerating conditions, like inappropriate temperature or moisture control, can also encourage pathogenic bacteria growth – therefore, spoiled food should always be discarded as a matter of safety.
The following is adapted from "How do you know if your food is safe to sell?" by Renee R. Boyer, Assistant Professor, Extension Specialist, Food Science & Technology Department, Virginia Tech
Factors that Affect Bacterial Growth on Foods: FAT TOM
If not prepared properly, microorganisms (bacteria, yeasts and molds) on the food, in the environment, or transferred by food handlers may lead to rapid spoilage or foodborne illnesses. Food spoilage microorganisms may change the aroma, texture, and/or appearance of food. Pathogens (microorganisms that make you sick) do not change the food’s sensory characteristics so we often do not know they are present. Practicing good sanitation and proper food safety techniques are important ways to prevent food from becoming contaminated with microorganisms. It is also important to make sure that microorganisms do not have a chance to grow within the food. Microbial growth is affected by the following six factors: Food, Acidity, Time, Temperature, Oxygen and Moisture, also known as FAT TOM. You must control one or more FAT TOM factors to prevent microorganisms (including pathogens that may be in the food) from growing to dangerous or toxic levels
Acidity – pH
The pH of a food is a measure of how acidic it is. The pH scale ranges from 0 – 14, with 7 being neutral. Water has a pH of 7. The pH is acidic if it is lower than 7 and basic if it is higher than 7. Each pH unit actually represents a tenfold difference. For example, if the pH goes from 4 to 3, there has been a 10-fold increase in acidity. Almost all foods fall below 7 on the pH scale, making them acidic in nature. The figure to the right shows where some foods fall on a pH scale. Most pathogens can grow at pH values between 4.6 and 9.0, but very acid or sour foods (pH below 4.6) discourage the growth of many microorganisms. Foods with a pH less than or equal to 4.6 are called high acid foods. Examples include fruits, jams, jellies, and honey. Products may be naturally high in acid or you might acidify products by adding acid (e.g., vinegar, wine, Worcestershire sauce, or lemon juice) to lower the pH. Pickling foods (by adding acid or through natural fermentation) lowers the pH enough to discourage many microorganisms. Foods with a pH greater than 4.6 are called low acid foods. Examples include milk, meat and vegetables.
Time and Temperature
Time and temperature are very closely related in
controlling microbial growth. Bacteria can double in number every 15 to 20 minutes, especially in the temperature range of 41°F to 135°F. This temperature range is referred to as the "temperature danger zone," because most microorganisms multiply quickly within this range. To control the growth of microorganisms, do not allow potentially hazardous foods to be held in the temperature danger zone for more than two hours.
For every 10°F increase in storage temperature the growth rate of bacteria doubles; for every 10°F decrease in storage temperature the growth rate is cut in half. Storing foods below 41°F will slow the growth of most pathogens extending the amount of time the food may be safely held for sale or consumption. Because pathogen growth is not stopped by refrigeration, potentially hazardous foods cannot be stored indefinitely. If potentially hazardous foods are mixed, prepared, handled, cut, wrapped, or packaged at a retail setting they may be stored a maximum of seven days at 41°F. The only reliable way to measure the temperature is with a calibrated thermometer inserted into the food.
Potentially hazardous cooked foods should be cooled within two hours from 135°F to 70°F and within four hours from 70°F to 41°F or less.
Potentially Hazardous or Time and Temperature Control for Safety (TCS) Foods are those that are capable of supporting the rapid and progressive growth of pathogenic microorganisms. In general, foods that have been processed and contain moisture fall within this category. Microbial growth in these foods can only be controlled using time and temperature. Controlling or altering other FAT TOM factors is not effective.
Examples of Potentially Hazardous (TCS) Foods
- Foods derived from plants that are heat treated including:
- Onions (cooked and rehydrated)
- Cooked rice
- Soy protein products (e.g., Tofu)
- Potatoes (baked or boiled)
- Cut melons and cut tomatoes
- Raw seed sprouts
- Leafy greens
- Garlic-in-oil and other vegetable-in-oil mixtures that are not treated to prevent the growth of
- Certain sauces, breads, and pastries containing meat, cheese, cooked vegetables
- Milk and dairy products
- Sour Cream
- Whipped Butter
- Meat and Poultry
- Shell eggs
- Poultry and poultry products
- Shellfish and crustaceans
Not all microorganisms need oxygen to grow. Some prefer levels of oxygen similar to atmospheric levels. These microorganisms are typically spoilage microorganisms such as yeasts and molds. Other microorganisms cannot grow in the presence of oxygen. Additionally, there is a third group of organisms that grow best with low oxygen – these are commonly the pathogens. Removing or reducing oxygen in food packages (by vacuum packaging or canning) or exchanging it with other gases (by using controlled atmosphere or modified atmosphere packaging) stops the growth of most spoilage microorganisms, but can encourage pathogens to grow. For example, Clostridium botulinum that causes botulism grows well in the absence of oxygen. If you do remove oxygen, you must control other FAT TOM parameters in order to prevent the growth of C. botulinum.
Moisture (Water Activity)
A measurement called water activity (aw) provides information about amount of water in a food product. Usually water activity correlates with moisture. Water activity, also called free water, is the amount of water available for microorganisms to use for growth. There may be other water present, but in an unusable or bound form. Water activity is measured on a scale from 0.0 to 1.0, where pure distilled water is 1.0. Just like oxygen and pH, water requirements vary among microorganisms. Typically, bacteria require lots of water. When that water is taken out of the product (or bound) most bacteria are no longer able to grow. Water can be bound by adding food ingredients such as salt and sugar. For this reason, jams and jellies which have high water content have comparatively low water activity due to the higher sugar content. Drying and freezing can also be used to alter water activity and make it unavailable for microorganisms. Foods such as jams, jellies, honey, breads, and cookies that have a water activity of 0.85 or less can be considered shelf stable and do not require refrigeration. Once jams and jellies are opened, storage under refrigeration extends shelf-life.
For more information on FAT TOM principles, see individual fact sheets about each factor, located online at http://pubs.ext.vt.edu/category/food-safety.html.
CDC A-Z Index of Foodborne Illnesses: www.cdc.gov/foodsafety/diseases/index.html
USDA FSIS Parasites and Foodborne Illness Fact Sheet:
"How do you know if your food is safe to sell?" by Renee R. Boyer: pubs.ext.vt.edu/FST/FST-9/FST-9.html
VA Cooperative Extension Fact Sheets: pubs.ext.vt.edu/category/food-safety.html
Centers for Disease Control and Prevention (CDC): www.cdc.gov
USDA Food Safety and Inspection Service (FSIS): www.fsis.usda.gov
Virginia Cooperative Extension, an educational outreach program of Virginia Tech and Virginia State University: www.ext.vt.edu