Multiple: Food Poisoning

Definition
Description
Demographics
Causes and Symptoms
Diagnosis
Treatment
Prognosis
Prevention
The Future
For more information

Definition

Food poisoning is a general term for any illness of the digestive system that results from eating food. The food may be contaminated by bacteria, viruses, parasites, chemicals, or natural toxins produced by certain plants or animals.

Description

Food poisoning is usually a disorder of the stomach and intestines resulting from contaminated food. The contamination may result from not cooking meat and other animal products thoroughly; from washing food in contaminated water; from failing to refrigerate leftover food promptly; or from food being handed by people who are carrying disease organisms. Some forms of food poisoning affect other parts of the body, especially the nervous system and/or kidneys.

Demographics

According to the Centers for Disease Control and Prevention (CDC), there are on average 76 million cases of food poisoning in the United States each year; most are mild illnesses that run their course in a few days with appropriate self-treatment at home. About 325,000 people, however, become sick enough to require hospital treatment, and 5,000 will die. Those at greatest risk of serious illness or death from food poisoning are the very young, the very old, people with weakened immune

systems, and people exposed to an unusually high dose of a disease organism.

The profile of foodborne diseases has changed over the years. At the turn of the twentieth century, such diseases as cholera, typhoid fever, and tuberculosis were the most common illnesses caused by contaminated food or water. The pasteurization of milk, safer methods of canning food, and better purification of drinking water have made these diseases increasingly rare in the developed world. Newer diseases have emerged, however, because bacteria mutate and evolve over time. In addition, air travel and other methods of rapid transportation mean that disease organisms that used to be limited to one part of the world can spread to other countries in days rather than years.

Causes and Symptoms

Food poisoning can be caused by a wide range of microorganisms, chemicals, and natural toxins. About 60 percent of cases of food poisoning in the United States and Canada are caused by bacteria that live in the intestines of chickens, turkey, and cattle, or by toxins produced by these bacteria; another 30 percent are caused by viruses. Food poisoning from chemicals or naturally poisonous plants or animals is less common.

• Bacterial infections. These are the most common type of food-borne illness in Europe and North America; 97 percent of these cases are related to improper food handling, 79 percent from food prepared in restaurants or cafeterias and 21 percent from improper cooking or storage of food at home.
• Parasites. These include tapeworms, flatworms, and amoebas, often found in raw fish or contaminated drinking water.
• Viruses. About 30 percent of cases of food poisoning in the United States result from eating food contaminated by Norwalk virus, rotaviruses, and certain forms of the hepatitis virus.
• Chemicals. Most cases of chemical contamination of food in the United States are caused by pesticide residue on fruits or vegetables, but there are also cases of people adding chemicals directly to food in the belief that they were using ordinary table salt.

A Treat to Die For

Most people would not think of eating an animal known to be poisonous as part of a gourmet meal in a fancy restaurant. For generations, however, the Japanese have considered fugu, or puffer fish, a great delicacy when the fish's flesh is sliced thin and served in an attractive pattern on a plate. Fugu can cost as much as $200.00 in one of the better restaurants in Tokyo. Unfortunately, the liver, skin, and intestines of the puffer fish contain a deadly nerve poison that has no antidote. The Japanese still remember a famous actor who ordered a serving of fugu liver one night in 1975 because he enjoyed the tingling sensation as it passed his tongue and lips. Within minutes, however, his arms and legs were paralyzed, then his breathing muscles. Eight hours later he died.

Although fugu is still served in Japan, chefs who prepare it must study for two years and pass a stiff examination to show that they can separate the fish into poisonous and nonpoisonous parts as well as prepare it for customers; only about 30 percent of the chefs succeed in passing the examination. More recently, scientists at Nagasaki University have reported success in breeding a nontoxic variety of puffer fish by restricting the fish's diet. According to the scientists, it is the food that the fish eats in the wild plus its digestive process that make its liver and intestines so poisonous to humans.

• Natural toxins. Natural toxins are substances produced by certain mushrooms and plants, and several species of reef fish that are poisonous to humans by ingesting toxins produced by algae that come through the food chain.

The most common symptoms of food poisoning are nausea, vomiting, abdominal cramping, and diarrhea. In the case of food poisoning caused by bacteria and viruses, the organisms either directly irritate the tissues that line the intestines or produce toxins that destroy the cells of the intestinal lining. The digestive tract secretes large quantities of fluid in order to flush the invaders out of the body, resulting in loose, frequent, and watery stools. Vomiting is caused by bacterial toxins acting on the central nervous system.

The timing of the symptoms varies, depending on the specific organism or natural toxin involved, the amount of food that the person ate, and the person's overall health. People can feel sick within a few hours, even a few minutes, after eating contaminated food, or it may take several days before they feel ill. Symptoms caused by parasites may not appear for two weeks or longer.

Diagnosis

Many people do not seek medical help for a mild case of food poisoning. If a person does go to the doctor, the doctor will begin by taking a history of the person's recent eating habits, including where, as well as what, they ate. Because food poisoning can occur as a group outbreak as well as affecting individuals, the doctor will want to know whether other people might be sick and whether the public health department should be notified.

In most cases the doctor will treat the patient for diarrhea and nausea without trying to determine the specific organism that contaminated the food, because laboratory tests for viruses or bacteria require specialized equipment and techniques. If the doctor thinks that it is important to identify the organism, he or she can take a sample of the patient's stool for laboratory analysis. This method can also be used to detect and identify parasites. In some cases the doctor may take a blood test if the patient has a high fever or other signs of an acute infection.

If the patient's food history indicates that they ate a poisonous plant or animal, they will usually be taken to a hospital as quickly as possible for specialized treatment.

Treatment

Treatment consists of rest and preventing dehydration. If the patient has lost a lot of body fluid from repeated episodes of diarrhea or vomiting, they are encouraged to drink clear liquids with small amounts of salt and sugar added. A solution to replace fluid can be made at home by adding one level teaspoon of salt and four heaping teaspoons of sugar to one quart of water. People who are severely dehydrated may need to be taken to the hospital and given fluids intravenously.

The doctor may also prescribe medications to stop the diarrhea, such as Pepto-Bismol or Kaopectate. If the patient's diarrhea lasts more than four days, the doctor will order a stool culture (sample to be sent to a laboratory to be tested) to identify the organism. Other signs that further treatment is needed are: fever higher than 101°F (38.3°C), blood in the stools, or prolonged vomiting and severe dehydration. Depending on the organism, the doctor may prescribe an antibiotic.

Prognosis

Most people recover completely from food poisoning in a few days. Complications are rare except in infants, the very old, and people with HIV infection or other diseases that weaken the immune system.

Prevention

People can reduce their risk of food poisoning by observing simple precautions recommended by the CDC when cooking at home:

• Cook meat, eggs, poultry, fish, and other animal products thoroughly. Ground beef should be heated to an internal temperature of 160°F (71°C), poultry to 180°F (82°C), and fish to 140°F (60°C).
• Separate foods. Do not cut fruits and vegetables on a cutting board that has been used for raw chicken or beef until the cutting board has been washed. Do not put cooked meat on a plate that has held raw meat.
• Chill leftovers promptly. Cooked food should be refrigerated within four hours after a meal to prevent bacteria from growing in it. Keep the refrigerator temperature at 40°F (4°C).
• Clean fruits and vegetables in running water and remove the outermost leaves of a head of cabbage or lettuce.
• Wash hands before and after food preparation; do not prepare food for others when ill.

• Report suspected foodborne illnesses to the local public health department; this includes foods purchased in supermarkets as well as eaten in restaurants.

Tips for food safety when traveling:

• Do not eat wild plants or mushrooms when hiking or camping.
• Drink only boiled water when traveling abroad, and avoid ice, salad, and raw fruits, vegetables and seafood. Eat only hot, freshly cooked food.
• Consult the CDC for travelers' advisories about specific countries.

The Future

New technologies may help to reduce the risk of food poisoning in the future by making foods safer. One technique that has already proven useful is irradiation of ground beef and other meats; another is a new way to pasteurize raw eggs in the shell. Another promising field of research is to study the ways in which disease organisms are spread among animals. Finding ways to prevent animals from becoming infected by bacteria and viruses would lower the rate of food poisoning among humans.

SEE ALSO Toxoplasmosis

WORDS TO KNOW

Carrier: A person who has an infectious disease and can transmit it to others but has no symptoms of the disease themselves.

Dehydration: Loss of water from the body. It may be caused by fever, vomiting, diarrhea, or excessive sweating.

Irradiation: A technique for treating raw meat and poultry with gamma rays, x rays, or electron beams to destroy disease organisms.

Pasteurization: A process in which milk or fruit juice is partially sterilized by heating to a temperature that destroys disease bacteria without causing major changes in appearance and taste.

Toxin: A poisonous substance produced by a living cell or organism.

For more information

BOOKS

Isle, Mick. Everything You Need to Know about Food Poisoning. New York: Rosen Publishing Group, 2001.

Roueché, Berton. Eleven Blue Men, and Other Narratives of Medical Detection. New York: Berkley Medallion, 1970. The title essay, an account of food poisoning caused by a chemical added to food in place of salt, is available online at http://lilt.ilstu.edu/pefranc/ROUECHE.00.html [accessed April 8, 2008].

Sheen, Barbara. Food Poisoning. Detroit, MI: Lucent Books, 2005.

PERIODICALS

Newman, Cathy. “Pick Your Poison—12 Toxic Tales.” National Geographic, May 2005. Available online at http://science.nationalgeographic.com/science/health-and-human-body/human-body/poison-toxic-tales.html (accessed April 8, 2008).

WEB SITES

Centers for Disease Control and Prevention (CDC). Foodborne Illness. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/foodborneinfections_g.htm (accessed April 8, 2008).

NOVA Online. The Most Dangerous Womanin America. http://www.pbs.org/wgbh/nova/typhoid/ (first aired 2004; accessed April 8, 2008). This web-site is a companion to a television show about Mary Mallon (1869–1938), a cook better known as Typhoid Mary, quarantined for life against her will because she was a carrier of typhoid fever, a common foodborne illness in the early 1900s.