Food Poisoning

Written by: SphynxCatVP
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A number of people cycle through the lists, the chatrooms and the message boards that claim that they can't eat normal food because they get various bad symptoms after eating. Since I have no way of knowing whether they're just experiencing food poisoning or if they've actually checked things out thoroughly, I don't feel it's my place to say, either way. :)

However, I can offer some illustrative examples of food poisoning so that you have a better chance of figuring it out for yourself. As always, how sick someone gets from bad food (I've seen extremes of hardly effected to laid up for a week feeling like they want to die) will depend on your immune system, and your current state of health, nutritional and otherwise.

Basic food poisoning information

An estimated 55% of (USA) food poisoning cases are caused by improper cooking and storage of foods, and 24% by poor hygiene (not washing hands before handling food). Only 3% of cases are from an unsafe food source. Keeping your hands clean while working with food is the single most important thing you can do to prevent food poisoning.

Several organisms can cause food poisoning. After eating food contaminated with bacteria, the bacteria multiply in the stomach and the bowels. Some bacteria give off a toxin when they multiply. As a result, nausea, vomiting, abdominal cramps and diarrhea commonly occur. Vomiting and diarrhea are the body's way of eliminating the toxin. Although the experience is unpleasant, most common cases of food poisoning run their course without needing medical attention provided the person has a normal immune system.

Most cases of gastrointestinal symptoms (nausea, vomiting, abdominal cramps and diarrhea) are due to viral infections and are not true cases of food poisoning. Diagnosis of true food poisoning is difficult because many different organisms are found in different kinds of food and all have different incubation periods. Not all food poisoning organisms cause vomiting as a symptom but almost all organisms cause diarrhea. Blood in the stool is seen in several types of food poisoning and is considered a serious symptom. Abdominal cramps are common, even if vomiting is not present. Fever is infrequent but may be seen. Contact a doctor if a fever or bloody stools are present.

Eating a substance and getting sick immediately afterwards is not the typical course for food poisoning. Most people are not aware that food eaten several days previously can be the cause of food poisoning (due to the varying incupation period of various pathogens). As with any illness, the symptoms you actually get will vary according to the variety of food-borne pathogen encountered, and the resistance of the individual to such illnesses.

When should you see a doctor?

Young children, elderly people and people with severe medical conditions are at a highest risk of dehydration (from diarrhea and/or vomiting) due to food poisoning. Contact your doctor if there is:

  • Diarrhea lasting longer than 24 hours
  • Vomiting lasting longer than 12 hours
  • Blood in the stool
  • Fever
  • Vomiting and diarrhea that are so intense that severe muscle cramping and pain occurs
  • An inability to keep down any liquids at all for 12 hours.

How can you prevent food-borne pathogens?

The first step in preventing food poisoning is to assume that all foods may cause food-borne illness. Follow these steps to prevent food poisoning:

  1. Wash hands, food preparation surfaces and utensils thoroughly before and after handling raw foods to prevent recontamination of cooked foods.
  2. Wash hands thoroughly after using the bathroom.
  3. Keep refrigerated foods below 40 degrees F.
  4. Serve hot foods immediately or keep them heated above 140 degrees F.
  5. Divide large volumes of food into small portions for rapid cooling in the refrigerator. Hot, bulky foods in the refrigerator can raise the temperature of foods already cooled.
  6. Remember the danger zone is between 40 degrees F and 140 degrees F.
  7. Follow approved home-canning procedures if you choose to can and store foods at home. These can be obtained from places such as USDA bulletins.
  8. Heat canned foods thoroughly before tasting.
  9. When in doubt, throw it out!!!

If you are in the food service profession, reading this should help you understand why it's a requirement to ALWAYS wash your hands after using the bathroom. Here is a listing of the more common causes of food poisoning cases. There is a glossary of selected terms at the bottom of this page.


Remember: This is not a complete list - only common causes!

  • Aerobic
    • Growing or thriving only in the presence of atmospheric oxygen.
  • Anaerobic
    • An organism, such as a bacterium, that can live in the absence of atmospheric oxygen. Not requiring air or oxygen for life; -- applied especially to those microbes to which free oxygen is unnecessary
  • Facultative
    • Capable of functioning under varying environmental conditions. Used to refer to certain organisms, such as bacteria, that can live with or without oxygen.

Pathogens with short (under 24 hrs) onset times


  • Incubation period: 8-16 hours
  • Duration: Up to 24 hours
  • Symptoms:
    • Cramps, diarrhea, nausea, vomiting
  • Cause:
    • Bacillus Cereus: Anaerobic bacteria that produce spores and are found in soil and any food. This bacteria causes two forms of illness - the emetic variety (making you throw up), and the diarrhea version.


  • Incubation period: 12-36 hours - death can occur within 24 hours if severe infection (.5 to 1.5 days)
  • Duration: 30-100 days, sometimes as long as a year
  • Symptoms:
    • Sore throat, vomiting, slurred speech, double/blurred vision, cramps, dry mouth, diarrhea, weak muscles and difficulty breathing. This toxin affects the nerves and if untreated, can cause paralysis and respiratory failure.
  • Cause:
    • Clostridium botulinium: Anaerobic bacteria that form spores with a high resistance to heat. Found in animal intestines, water contaminated with fecal matter, and soil. Spores are highly resistant to destruction. Pressure cooking at 240° F (120° C) for 30 minutes can kill spores. The bacteria (not the spores) are readily destroyed by boiling at 212° F (100° C) for 10 minutes or heating to 176° F(80° C) for 30 minutes.
  • Notes:
    • Fatality rate (untreated) is up to 25%. Diagnosis can be complicated by being confused with other muscle weakness disorders such as Guillain-Barre syndrome, myasthenia gravis, polio, encephalitis, diphtheria, and various adverse drug reactions, etc. Accurate diagnosis is essential!


  • Incubation period: 8-22 hours
  • Duration: Commonly 24 hours, but can be up to 2 weeks
  • Symptoms:
    • diarrhea, nausea, cramps, possible fever, vomiting (rare)
  • Cause:
    • Clostridium Perfringens: spore-forming anaerobic bacteria that can withstand most cooking temperatures and are found in soil, dust and the intestinal tract of animals. The only way to kill the spores is to pressure cook at 15-pounds steam pressure to reach 250 degrees (F).
  • Notes:
    • The necrotic enteritis form is very rare in the USA, but when it occurs, is often fatal.


  • Incubation period: 6-48 hours (.25 to 2 days)
  • Duration: 5-7 days
  • Symptoms:
    • Headache, severe diarrhea, cramps, fever. Can be fatal or lead to arthritis, meningitis and typhoid.
  • Cause:
    • Salmonella: Aerobic bacteria that lives and grows in the intestines of humans, animals, birds and insects. Commonly an issue with eggs or egg products. Bacteria can be found on the eggshell as well as inside the egg.
  • Note:
    • Symptoms are similar to Campylobacteriosis, and potential long-term consequences are simliar.


  • Incubation period: 12-48 hours (.5 to 2 days)
  • Duration: 5-7 days
  • Symptoms:
    • Watery or bloody diarrhea, cramps, fever, dehydration. Tiredness, nausea and vomiting. Diarrhea may last for months after the disease is no longer there.
  • Cause:
    • Shigella dysenteriae, S. flexneri, S. boydii, and S. sonnei: Outbreaks of shigellosis frequently occur in tropical or temperate climates, especially in areas with severe crowding and/or poor hygiene, which sometimes occur in day care and institutional settings. Some people have no symptoms but can still pass the bacteria to others. An extremely low number of organisms (10-100) is needed to transmit Shigella.


  • Incubation period: 1-7 hours, 2-4 being most common
  • Duration: 2-3 days
  • Symptoms:
    • Vomiting, nausea, diarrhea, cramps
  • Cause:
    • Staphylococcus aureus: Facultative bacteria found in the nose, throat, and in skin infections of humans. Bacteria CANNOT be destroyed by heat. Man's respiratory passages, skin and superficial wounds are common sources of S. aureus. Commonly found in foods requiring a lot of physical handling such as chicken/tuna/potato salads, and anything left in the temperature "danger zone" for too long.

Pathogens with medium (over 24 hrs) onset times


  • Incubation period: 2-10 days
  • Duration: 7-10 days, relapses common
  • Symptoms:
    • Diarrhea (often bloody), abdominal cramping and pain, nausea and vomiting, fever, tiredness, headache
  • Cause:
    • Campylobacter jejuni, C. fetus, and C. coli are the types that usually cause campylobacteriosis in people. C. jejuni causes most cases of the illness.
  • Notes:
    • Long-term consequences MAY sometimes result from a Campylobacter infection. Some people may develop a rare disease called Guillain-Barré syndrome (GBS) that affects the nerves of the body following campylobacteriosis. When it happens, it occurs several weeks after the diahreal portion of the Campylobacter infection. Other potential complications include a reactive arthritis called "Reiters Syndrome" (especially in those with HLA-B27 antigen), meningitis, or infect the abdominal cavity, the heart, urinary tract and the blood stream.

E. coli

  • Incubation period: 2-5 days
  • Duration: up to 9 days, commonly about 4 days
  • Symptoms:
    • Abdominal cramps, watery diarrhea, grossly bloody diarrhea described as "all blood and no stool", abdominal pain described as equal in intensity to labor pains, vomiting (occasional), tiredness
  • Cause:
    • Escherichia coli is a common organism found in the intestinal tract of man and animals and, like some other potential pathogens, it is also readily found in damp, ambient temperature environments e.g. soil, vegetation, moist or wet areas in factories, untreated water etc. There are many types and strains of E.coli, a few of which are potentially pathogenic. It grows when there is inadequate cooking and/or recontamination of cooked product. Can grow at refrigeration temperatures.
  • Notes:
    • In 2% to 7% of cases, the bacteria may cause kidney failure.


  • Incubation period: 1-4 days
  • Duration: Unknown
  • Symptoms:
    • nausea, vomiting, diarrhea
    • Cause:
      • Various species of Streptococcus bacteria which are facultative anaerobes. Some are transmitted by animals and workers contaminated with feces, others from the nose and throat of infected humans.
    • Notes:
      • Untreated strep infections can lead to rheumatic fever, which itself runs the risk of rheumatic heart disease when it attacks the heart valves (if it damages the heart valves seriously enough, you WILL require eventual heart transplant) , as well as other complications.

    Typhoid fever

    • Typhpoid incubation: 3-56 days, commonly 7-14 days
    • Paratyphoid incubation: 1-10 days
    • Duration: 4 weeks
    • Symptoms:
      • Headache, severe diarrhea, cramps, fever. Can be fatal or lead to arthritis, meningitis and typhoid.
    • Cause:
      • Salmonella Typhi: Aerobic bacteria that lives and grows in the intestines of humans, animals, birds and insects.
    • Notes:
      • Modern sanitation seems to have eliminated most cases of this, however some people (about 5% of those who recover) can become carriers of the disease and not know it - and if they work in food service, they can start a rash of cases.

Pathogens with long (1 week or more) onset times

Hepatitis, Infectious A/E

  • Incubation Hep A: 2-6 weeks / Hep E: 10-50 days
  • Duration Hep A: 3-9 months / Hep E: 6 months or more
  • Symptoms:
    • Jaundice, fever, cramps, nausea, lethargy
  • Cause:
    • Hepatitis A/E: grows in feces of infected humans and human carriers. Transmitted by water and from person to person and infects the liver.

Uncommon pathogens


  • Incubation period: Varies by individual and amount ingested - could be hours to weeks
  • Duration: Varies by individual
  • Symptoms:
    • Hallucinations, convulsions, staggering, belligerence, gangrene of extremities
  • Cause:
    • Ergot, a fungal mold that grows on wheat, rye and some varieties of rice. Also found in pesticides on fruits and vegetables, cyanide in silver polish, zinc inside tin cans and copper pans.
  • Notes:
    • Not very common anymore with the advent of commercial processing. Still known in the veterinary field, however.

Listeria / Listeriosis

  • Incubation period: Depends on the form
  • Duration: Depends on the form, but often 7-10 days.
  • Symptoms:
    • Fever, muscle aches, nausea, darrhea. If infection spreads to the nervous system it can lead to meningitis, with symptoms of headache, stiff neck, confusion, loss of balance, or convulsions. Infections during pregnancy can lead to miscarriage or stillbirth, premature delivery, or an infection in the newborn.
  • Cause:
    • Listeria is found in soil and water; vegetables may be contaminated from the soil or from manure used as fertilizer.
  • Notes:
    • Listeria is killed by pasturization and cooking, however in ready-to-eat foods, contanimation may occur after cooking and processing, but before packaging.


  • Incubation period: 4-28 days
  • Duration: mild symptoms, 2-3 weeks. Severe symptoms, 2-3 months - can be fatal
  • Symptoms:
    • Fever, diarrhea, sweating, muscle pain, vomiting, skin lesions
  • Cause:
    • Trichinella Spiralis: a spiral worm that lives in the intestines where it matures and lays eggs and later invades muscle tissue. Transmitted by infected swine and rats. Once infected, the worms lay eggs in the intestinal tract. Once they hatch, the larvae migrate throughout the muscles. Swelling, generalized pain, fever, heart problems and other symptoms will develop at that point.
  • Notes:
    • Factors that may impact morbidity are the quantity of larvae ingested, the species of Trichinella (most notably T spiralis), and the immune status of the host patient. Patients succumb to exhaustion, pneumonia, pulmonary embolism, encephalitis, or cardiac failure and/or arrhythmia. Death from trichinellosis usually occurs in 4-8 weeks but may occur as early as in 2-3 weeks.