Food Safety Education

Food Safety Education

Organisms Associated with Foodborne Illness

Hilary Shallo Thesmar, Ph.D., R.D.

Many people have experienced some type of foodborne illness at some point in their life.  When the symptoms first appear, most people think, “What did I eat at my most recent meal?”  Did you know that most people do not feel ill until 2-7 days later, sometimes weeks after eating the contaminated food?  There are a few organisms that cause illness within a few hours, but most take a day or more to cause symptoms. 

There are two ways that organisms can cause illness, infection and intoxication.  Infection is caused by the organism entering the body and growing. The organisms can be bacteria, viruses or parasites.  Intoxication is caused by toxins or poisons that the organisms produce either in the food or once in the body.

Below is a table of organisms or toxins in foods that cause illness in humans and the associated symptoms and time until symptoms occur.  The foods that are commonly associated with these organisms are in the last column.  This is based on historical data from the CDC and only applies to contaminated foods.  Most food is very safe and free of disease causing organisms if handled, stored and cooked properly. 

What can you do to help reduce your chances of becoming ill? 

  • Wash hands before preparing or touching any food
  • Cook food properly (use food thermometers)
  • Refrigerate foods to less than 40 °F (use thermometer)
  • Keep raw and cooked food separate (don’t let raw meat or anything that touches raw meat come in contact with food that is ready to eat such as a salad, fruit or bread)
  • Replace sponges and wash towels often
  • Clean counter tops, utensils and cutting boards thoroughly
  • Clean out refrigerator frequently (discard old food)
  • “When in doubt, throw it out!”
Organism or toxin Time for symptoms to appear Symptoms Associated foods
Staphylococcus aureus toxin

1-6 hours

Nausea Vomiting, diarrhea, abdominal pain

Foods that require considerable handling during preparation and that are kept at slightly elevated temperatures after preparation (salads, cream pastries).  S. aureus produces a toxin that is not destroyed by heat, so be sure to discard foods that have been at room tempetature for 2 hours or more.

Clostridium perfringens

2 to 36 hours (usually 6-12 hours)

Abdominal cramps, diarrhea, sometimes nausea and vomiting

Temperature abused  prepared foods, Meats, meat products, and gravy

Salmonella species

12 to 74 hours (usually 18 to 36 hours)

Abdominal cramps, diarrhea, vomiting, fever, chills, nausea, headache.

Raw meats, poultry, eggs, milk and dairy products, fish, shrimp, frog legs, yeast, coconut, sauces and salad dressing, cake mixes, cream-filled desserts and toppings, dried gelatin, peanut butter, cocoa, chocolate and nuts

E. coli

12-74 h,
mean 18-36 h

Severe bloody diarrhea and abdominal cramps; nonbloody diarrhea, little or no fever

Undercooked contaminated ground beef, raw milk or juice, contaminated water, sprouts, or lettuce


2 to 5 days, illness lasts 7-10 days with relapses

Diarrhea, fever, abdominal pain, nausea, headache and muscle pain

Raw or undercooked chicken, raw milk, contaminated water

Listeria monocytogenes

48 to 72 hours but up to 30 days

Fever, headache, nausea, vomiting

Soft cheese, unpasteurized milk, deli meats, hot dogs, refrigerated foods

Norwalk virus, Norwalk-like virus

24-48 h , illness lasts for  24-60 hours

Mild illness with nausea, vomiting, diarrhea, and abdominal pain.

Headache and low-grade fever may occur

Contaminated water, shellfish

Improper hygiene and food handling is a frequent cause

Table adapted from FDA Bad Bug Book

And Partnership for Food Safety Education


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