food poisoning

food poisoning

food poisoning, acute illness following the eating of foods contaminated by bacteria, bacterial toxins, natural poisons, or harmful chemical substances. It was once customary to classify all such illnesses as "ptomaine poisoning," but it was later discovered that ptomaines, the products of decayed protein, do not cause illness. The symptoms, in varying degree and combination, include abdominal pain, vomiting, diarrhea, headache, and prostration; more serious cases can result in permanent disability or death.

Bacterial Food Poisoning

In general, the bacteria that cause food poisoning do not affect the appearance, aroma, or flavor of food. The most common bacterial causes of food poisoning are Salmonella (see salmonellosis), staphylococcus, Escherichia coli, Listeria monocytogenes, Shigella, and Campylobacter jejuni. The symptoms may be caused by toxins produced by the bacteria. The most serious type of food poisoning caused by bacterial toxins is botulism, which results from toxins made by the bacterium Clostridium botulinum.

Salmonella, most notoriously spread via raw eggs, develops from 6 to 72 hours after exposure. Symptoms include severe diarrhea, fever and chills, vomiting, and abdominal cramps and usually last from three to five days. Staphylococcal food poisoning is actually caused by the potent toxins that they produce. Typical sources are unrefrigerated ham, poultry, potato or egg salad, and custards. Carriers and food handlers with staphylococcal skin infections are mainly responsible for the spread of staphylococcus toxin poisoning. The onset of symptoms from such poisoning (similar to those of Salmonella infection) occurs abruptly one to six hours after ingestion of the polluted food. The illness lasts from 24 to 48 hours; fatalities are rare.

Infection with a particular strain of the usually harmless E. coli began to appear in food poisoning cases from the 1980s on, typically in raw or undercooked ground meat. Onset of symptoms comes one to eight days after eating the contaminated food. Symptoms include bloody diarrhea, nausea, and sporadic vomiting, with or without fever. It can progress to kidney failure and death, especially in children.

Listeriosis, caused by the bacterium Listeria monocytogenes, is spread in soft cheeses, undercooked meats, and prepared foods from delicatessen counters. Its onset is abrupt. Symptoms vary with the person's immune status and may include fever, muscle aches, fatigue, and nausea. The illness is especially serious for the very young or for pregnant women, who may miscarry or transmit blood infections or meningitis to the baby. In adults, the disease can progress to central nervous system complications, endocarditis, or pneumonia, and is an especially serious threat to the elderly.

Shigella is spread by contaminated food or from person to person (principally via a fecal-oral route). New strains of bacteria of the genus Shigella have been associated with food poisoning from ground meat. Symptoms include watery diarrhea, abdominal cramps, and bloody mucus in the stools.

Campylobacter enteritis is caused by either of two species of the Campylobacter bacterium. The bacterium is ubiquitous in uncooked poultry. Symptoms (diarrhea, fever, chills, headache) arise 2 to 11 days after exposure and last one to two weeks. Although usually mild, the infection can cause Guillain-Barré syndrome, a weakness of the peripheral nerves that can lead to paralysis and death.

Treatment for most bacterial food poisoning includes rest, sedation, and replacement of fluid loss if necessary. Antibiotics usually are used only in severe cases. Preventive measures in the home include thorough cooking and prompt refrigeration of meats and eggs, washing and peeling fruits and vegetables (and avoiding uncooked produce entirely if a person has a compromised immune system), washing of cooking surfaces and utensils that may have been contaminated by uncooked foods, and careful handwashing after use of the toilet.

Since the 1970s the number of food poisoning cases in the United States has gradually increased, and beginning in the 1980s more virulent organisms and more serious cases of food poisoning with complications leading to miscarriage, kidney failure, or death were observed. Some experts have attributed this to overprescription of antibiotics and the routine use of antibiotics as growth enhancers and to treat disease in livestock, practices that encourage the development of drug-resistant bacterial variants. An increase in the consumption of uncooked fresh produce has also contributed to the increase in food-borne illnesses. The increase in the number and severity of food poisoning cases have led to concern about food inspection and preparation methods, and to the Food and Drug Administration's approval of irradiating some high-risk foods to eliminate bacterial contamination. More stringent meat inspection procedures were put in place by the U.S. Dept. of Agriculture in 1996 in response to some of these concerns, and the FDA approved the irradiation of meat. The vast majority of food poisoning cases, however, involve fruits and vegetables, seafood, cheese, and products, such as juices or deli salads, made with them. In 2008 the FDA allowed spinach and iceberg lettuce to be irradiated to kill bacteria.

Food Poisoning by Natural Poisons and Metals

Nonbacterial food poisoning may occur after eating foods that contain a naturally occurring or acquired deleterious substance. Ingestion of poisonous mushrooms or toadstools (see mushroom poisoning) may be followed in a matter of several minutes to two hours by severe thirst, abdominal cramps, diarrhea, vomiting, sweating, dizziness, confusion, collapse, coma, and, occasionally, convulsions. Poisoning may occur also after the ingestion of immature or sprouting potatoes because of the presence of solanine, an alkaloid. Mussels and clams that have fed on poisonous plankton also are a cause of food poisoning, since the poisonous substance is not destroyed by cooking. Ergot poisoning, caused by ingestion of rye grain infected with that fungus, causes damage to the blood vessels and gangrene, as well as gastrointestinal and neurologic symptoms.

It is also possible to take into the body poisons such as arsenic, lead, or mercury via foods that have been accidentally contaminated or sprayed with preservatives and not properly cleansed before ingestion. Food stored in containers lined with cadmium has been known to cause poisoning. Typical symptoms of this sort of food poisoning (diarrhea, vomiting) may occur right away; the nervous system and respiratory systems may be affected with continued exposure.


See J. P. Monahan, Food Poisoning (1984); J. N. Hathcock, ed., Nutritional Toxicology (1989); D. O. Cliver, ed., Foodborne Diseases (1990).

Scombroid food poisoning is a foodborne illness that results from eating spoiled (decayed) fish. It is the second most common type of seafood poisoning, second only to ciguatera. However it is often missed because it resembles an allergic reaction. It is most commonly reported with tuna, mahi-mahi, bonito, sardines, anchovies, and related species of fish that were inadequately refrigerated or preserved after being caught. Scombroid can result from inappropriate handling of fish during storage or processing. One of the toxic agents implicated in scombroid poisoning is a chemical called histamine. Other chemicals have been found in decaying fish flesh, but their association to scombroid fish poisoning has not been clearly established.


Unlike many types of food poisonings, this form is not produced by an organism or virus. Histidine exists naturally on many types of fish, and at temperatures above 60 degrees Fahrenheit on air contact it is converted to the biogenic amine histamine via the enzyme histidine decarboxylase produced by Morganella morganii (this is one reason why fish should be stored at low temperatures). Histamine is not destroyed by normal cooking temperatures, so even properly cooked fish can be affected. Histamine is a mediator of allergic reactions, so the symptoms produced are those one would expect to see in severe allergic responses. The suspect toxin is an elevated level of histamine generated by bacterial breakdown of histidine in the muscle protein through elevated production of the enzyme histidine decarboxylase. This natural spoilage process is thought to release additional by-products, which cause the toxic effect. Freezing, cooking, smoking, curing and/or canning do not destroy the potential toxins.


Symptoms consist of skin flushing, throbbing headache, oral burning, abdominal cramps, nausea, diarrhea, palpitations, a sense of unease, and, rarely prostration or loss of vision. Symptoms usually occur within 10-30 minutes of ingesting the fish and generally are self-limited. Physical signs may include a diffuse blanching erythema, tachycardia, wheezing, and hypotension or hypertension. People with asthma are more vulnerable to respiratory problems such as wheezing or bronchospasms. Symptoms of poisoning can show within just minutes, and up to two hours, following consumption of a spoiled dish. Symptoms usually last for approximately four to six hours and rarely exceed one to two days.


The first signs of poisoning suggest an allergic reaction with the following symptoms:

  • facial flushing/sweating
  • burning-peppery taste sensations in the mouth and throat
  • dizziness
  • nausea
  • headache
  • tachycardia
  • cold like symptons

Additional Symptoms

The above symptoms can advance to the following:


In the worst cases, the poisoning may:

  • blur vision
  • cause respiratory stress
  • cause swelling of the tongue


Treatment is in the form of supportive care such as fluids and oxygen. H1 and H2 receptor (histamine receptors) blocking medications can also be given with some success.


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