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Foodborne illness (food poisoning) is costly, both in dollars and in lives. The economic cost in the United States alone has topped $15.6 billion a year. Of course, the cost in lives is far greater.

Although most people who get food poisoning do not die, some do—over 3,000 annually in the United States. And foodborne illnesses are even more commonplace in underdeveloped countries.

Foodborne PathogenA foodborne illness may be caused by a variety of things associated with foods. Bacteria, viruses, parasites, natural plant toxins, and commercial chemicals can all cause foodborne illnesses. This publication deals with foodborne illnesses caused by the microorganisms we think of as germs— bacteria and viruses.

If you contract a foodborne illness you may think you have the flu or a virus that is going around.

This is natural because the symptoms of food poisoning are similar to those of other illnesses. These symptoms often include diarrhea, vomiting, abdominal cramps, fever, chills, and headache.

In contagious diseases, you contract the disease from another human. With foodborne illnesses, the germs are on food or in water. Humans or animals may transfer the germs to the food or water, but you actually contract the illness from what you eat or drink.

Bacteria and viruses are located almost everywhere—in the soil, water, and air. Therefore, it is very difficult to rid a food product of all germs. The necessary conditions for germs to grow include:

  • Nourishment—foods are an excellent source.
  • Correct temperature—between 40 and 140 degrees Fahrenheit. When foods are not in the refrigerator or being cooked, they will usually be in this range.
  • Time to grow.

As the following table shows, very little time is needed for germs to grow. It takes only about 20 minutes for them to double their number if the conditions are right. A single bacterium can reproduce to over 60 in 2 hours, to over 500 in 3 hours, to over 2 million in 7 hours. When you consider that many bacteria may be present in the beginning, you can see how important it is to take precautions, including good personal hygiene and proper food handling.

E coliThis publication can help you avoid foodborne illnesses by providing you with:

  • Descriptions of the major microorganisms as they relate to foodborne illnesses.
  • Habitat—where the germs are found.
  • Foods involved—water and foods that are a good place for the germs to live.
  • Method of transmission—how you can get the illness.
  • Symptoms—signs of sickness.
  • Onset—how long it takes for you to get sick.
  • Duration—how long the illness may last.
  • Prevention—what you can do to keep from getting sick.

The number of germs required to cause illness varies between types of germs and between individuals. Those people most vulnerable to foodborne illnesses include the elderly, infants, and people who are already sick. The people in these groups have one thing in common: their immune systems are not as capable of fighting off germs.

For more detailed information about a certain foodborne illness, contact your county Extension agent or local health department.

Table 1. Bacterial Growth Rate



Table 2. Bacteria In Foods

BacteriaDescriptionHabitatFoods InvolvedMethod of TransmissionSymptomsOnsetDurationPrevention
Bacillus cereusGrows well in a normal atmosphere and survives normal cookingSoil, dust, and spicesGrain products, rice, starchy foods, puddingsEating contaminated foods not properly cookedNausea, abdominal cramps, diarrhea, vomiting2-16 hours1 dayKeep cooked food hot (above 140 ̊F) or consume quickly.

Campylobacter jejuni

Widespread in nature; cause of meningitis and urinary infectionsIntestinal tracts of humans and animalsUnpasteurized milk, undercooked poultry, raw meat, untreated waterDrinking contaminated water, eating contaminated food, infected handlers, rodents, insectsNausea, cramps, headache, fever, diarrhea12-36 hours2-7 daysCook properly and reheat to 165°F.

Clostridium botulinum

Causes botulism; produces a deadly toxin under a vacuum; very rareSoil, plants, fishHome-canned foodsImproper methods of home canningBlurred vision, respiratory distress, and possible death12-48 hoursVaries widelyToxin is destroyed by boiling for 10 minutes.

Clostridium perfringens

Very common; called the “buffet germ;” grows rapidly in large portions of food, such as beef roastDust, soil, intestinal tracts of humans and animals.Meat and poultry dishes, sauces and graviesImproper temperature control, handler contaminationDiarrhea, cramps, nausea (no vomiting)8-15 hours12-24 hoursHeat foods quickly, then cool

Escherichia coli

Occurs worldwide; known as “tourist diarrhea” or “traveler’s dysentery”Intestinal tracts of humans and animalsPrimarily animal products and waterFoods and water contaminated by handlers and fliesDiarrhea, chills, headache, cramps, fever1-3 days2-9 daysAvoid contaminated foods. Cook foods thoroughly. Use proper personal hygiene.

Escherichia coli 0157:H7

Intestinal tracts of humans and some mammalsWater, raw milk, raw or rare ground beef, unpasteurized fruit juices, unwashed fruits and vegetablesFoods contaminated by animal fecesDiarrhea or bloody diarrhea, abdominal cramps, nausea, malaise2 days to 2 weeksUsually 8 days but can last monthsCook meat to proper internal temperature. Wash and peel fresh fruits and vegetables. Purchase pasteurized fruit and vegetable juices.

Listeria monocytogenes

Cause of Listeriosis; widespread in air, soil, water; attacks those with weak immune systemsIntestinal tracts of humans and animalsSoft cheeses, contaminated milk, raw milk, undercooked meats, vegetablesContaminated foodsHeadache, nausea, fever, vomiting1-12 days2-7 daysCook foods thoroughly. Use pasteurized milk. Chill foods rapidly.

Salmonella (species)

Cause of salmonellosis; over 2,000 species; very commonIntestinal tracts of humans and animalsPoultry, eggs, red meats, dairy productsContaminated foods, contact with infected person or rodentHeadache, vomiting, diarrhea, cramps, and fever12-36 hours2-7 daysCook foods thoroughly and reheat to at least 165 ̊ F.

Yersinia enterocoliticus

Also known as Pasteurella or YersiniosisUntreated water: streams, pondsPork, meats, raw milk, leftoversContaminated water or foodsCramps, fever, headache, diarrhea, vomiting24-36 hours3 daysProperly cook and handle foods

Shigella dysenteriae

Cause of shigellosis or bacillary dysentery; occurs mainly in fall and winterIntestinal tracts of humansMost foods and waterSpread of fecal contamination to food handlers and foodsFever, loss of appetite, vomiting, cramps, massive diarrhea1-7 daysAbout one weekGood personal hygiene. Cook foods thoroughly. Chill rapidly.

Staphylococcus aureus

Cause of “staph;” increased occurrence during the summerNose, throat, and open woundsMeat and seafood salads, sandwich spreadsSpread by infected food handlersNausea, vomiting, diarrhea30 minutes to 8 hours1-2 daysChill foods rapidly. Avoid holding foods between 40° and 140 ̊F. Good personal hygiene.

Streptococcus pyrogenes

Cause of streptococcal infections (scarlet fever and “strep throat”)Respiratory tract and nasal passagewayMilk, ice cream, eggs, potato salad, puddingsSpread to food by coughing or sneezingSore throat, tonsillitis, fever, headache, nausea, vomiting, occasional rash1-3 daysSeveral weeksCook foods rapidly. Chill rapidly.

Vibrio parahemolyticus

Needs salt to grow. Found in seawater.Aquatic waters and shellfishRaw fish and shellfishImproperly cooked and recontaminated foodsDiarrhea, cramps, vomiting, headache, fever12-48 hours2-5 daysProperly cook and handle seafood.

Vibrio cholera

Found in seawater.Fish and shellfish, crustaceansRaw seafood: oysters, shrimp, crabs, and clamsImproper cookingDiarrhea, weakness, chills, nausea3-76 hours1-8 daysProperly cook and handle seafood.

Vibrio vulnificus

Occurs naturally rather than as a result of pollution.Warm coastal watersRaw shellfishImproper cooking, eating raw seafoodHeadache, cramps, diarrhea12-24 hours3-6 daysProperly cook and handle shellfish.


Table 3. Virus In Foods

BacteriaDescriptionHabitatFoods InvolvedMethod of TransmissionSymptomsOnsetDurationPrevention

Hepatitis A

Causes about 500,000 illnesses a year; seasonalOnly in humansMilk, raw shellfish, potato saladFoods contaminated by infected workers, contaminated waterFever, nausea, abdominal cramps10-50 daysSeveral monthsProperly cook foods. Use good personal hygiene.


Difficult to avoid in undercooked foods and contaminated waterContaminated water, sewageSeafood, ice, waterContaminated waterDiarrhea, nausea, vomiting, cramps1-2 days2-3 daysProperly cook foods, boil water. Use good personal hygiene.


Very rare; cause of foodborne polioContaminated waterMilk and other beveragesContaminated waterFever, vomiting, headache, paralysis5-35 daysWeeks to monthsProperly cook foods. Use good personal hygiene.


How to Fight the Food Spoilers

  • When shopping for food, pick up perishable foods, meat, poultry, and dairy items last; get them home and into the refrigerator or freezer quickly.
  • Never buy food in damaged containers such as leaking, bulging, or severely dented cans, cracked jars, or jars with loose or bulging lids.
  • Maintain a refrigerator temperature of 40 degrees F (2 to 4 degrees C) or below, and a freezer temperature of 32 degrees F (0 degrees C) or lower. Check each frequently.
  • Thaw meat and poultry in the refrigerator or, for faster results, in a watertight package under cold running water.
  • Wash hands thoroughly with soap and warm water before handling foods.
  • After handling raw foods such as meat, poultry, vegetables, or fruits, wash your hands before touching other foods or food surfaces.
  • Wash utensils, containers, and work surfaces before and after they come into contact with raw foods, especially meat or poultry.
  • Always keep hot foods hot (above 140 degrees F) and cold foods cold (below 40 degrees F).
  • Refrigerate leftovers promptly in properly covered containers.

If You Think Someone Has a Foodborne Illness:

  1. Preserve the evidence. Wrap remaining food securely, mark “DANGER,” and freeze it. Save all the packaging material. Write down all available information about the food and symptoms. Save any identical unopened products.
  2. Seek treatment as necessary. If the victim is in an at-risk group or if symptoms persist or are severe (bloody diarrhea, excessive nausea and vomiting, high temperature), call your doctor.
  3. Call the local health department if the suspect food was served at a large gathering, from a restaurant, or if it is a commercial product.
  4. Call the USDA Meat and Poultry Hotline(1-800- 535-4555) if the suspect food is a USDA-inspected product and you have all the packaging.


Download a PDF of The Food Spoilers: Bacteria and Viruses, HE – 0654.

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