Food Poisoning

Food Poisoning Overview

Food poisoning is a common, usually mild, but sometimes deadly illness. Typical symptoms include nausea, vomiting, abdominal cramping, and diarrhea that come on suddenly (within 48 hours) of consuming a contaminated food or drink. Depending on the contaminant, fever and chills, bloody stools, dehydration, and nervous system damage may follow. These symptoms may affect one person or a group of people who ate the same thing (this would be called an outbreak).
The Centers for Disease Control and Prevention (CDC) estimates that in the United States alone, food poisoning causes about 76 million illnesses, 325,000 hospitalizations, and up to 5,000 deaths each year. One of the most common bacterial forms of infection, the salmonellae organisms, account for one billion dollars in medical costs and lost work time.
Worldwide, diarrheal illnesses are among the leading causes of death. Travelers to developing countries often encounter food poisoning in the form of traveler's diarrhea or "Montezuma’s revenge." Additionally, there are new global threats to the world's food supply through terrorist actions using food toxins as weapons.


Food Poisoning Causes

More than 200 known diseases can be transmitted through food. Those are just the ones we know about. The CDC estimates unknown or undiscovered agents cause 81% of all food–borne illnesses and related hospitalizations. Many cases of food poisoning are not reported because people suffer mild symptoms and recover quickly. Also, doctors do not test for a cause in every suspected case because it does not change the treatment or the outcome.

The known causes of food poisoning can be divided into two categories: infective agents and toxic agents.

Infective agents include viruses, bacteria, and parasites.


Toxic agents include poisonous mushrooms, improperly prepared exotic foods (such as barracuda), or pesticides on fruits and vegetables.

Food usually becomes contaminated from poor sanitation or preparation. Food handlers who do not wash their hands after using the bathroom or have infections themselves often cause contamination. Improperly packaged food stored at the wrong temperature also promotes contamination.


Food Poisoning Symptoms

Symptoms of food poisoning depend on the type of contaminant and the amount eaten. The symptoms can develop rapidly, within 30 minutes, or slowly, worsening over days to weeks. Most of the common contaminants cause nausea, vomiting, diarrhea, and abdominal cramping. Usually food poisoning is not serious, and the illness runs its course in 24–48 hours.
Viruses account for most food poisoning cases where a specific contaminant is found.

Norwalk virus: Causes a mild illness with nausea, vomiting, diarrhea, abdominal pain, headache, and low–grade fever. These symptoms usually resolve in two to three days. It is the most common viral cause of adult food poisoning and is transmitted from water, shellfish, and vegetables contaminated by feces, as well as from person to person.


Rotavirus: Causes moderate to severe illness with vomiting followed by watery diarrhea and fever. It is the most common cause of food poisoning in infants and children and is transmitted from person to person by fecal contamination of food and shared play areas.


Hepatitis A: Causes mild illness with sudden onset of fever, loss of appetite, and feeling of tiredness followed by jaundice, which is a yellowing of the eyes and skin. It is transmitted from person to person by fecal contamination of food.

Bacteria can cause food poisoning by two different ways. Some bacteria infect the intestines, causing inflammation and problems with normal absorption of nutrients and water that leads to diarrhea. Other bacteria produce chemicals in foods (known as toxins) that are poisonous to the human digestive system. When eaten, these chemicals can lead to nausea and vomiting, kidney failure, and even death.

Salmonellae: Salmonellae are bacteria that may cause food poisoning; the illness itself is often referred to as Salmonella or Salmonella infection. Salmonellae cause a moderate illness with nausea, vomiting, crampy diarrhea, and headache, which may come back a few weeks later as arthritis (joint pains). In people with impaired immune systems (such as people with kidney disease or HIV/AIDS or those on chemotherapy for cancer), Salmonellae can cause a life–threatening illness. The illness is transmitted by undercooked foods such as eggs, poultry, dairy products, and seafood.


Campylobacter: Causes mild illness with fever, watery diarrhea, headache, and muscle aches. Campylobacter is the most commonly identified food–borne bacterial infection encountered in the world. It is transmitted by raw poultry, raw milk, and water contaminated by animal feces.


Staphylococcus aureus: Causes moderate to severe illness with rapid onset of nausea, severe vomiting, dizziness, and abdominal cramping. These bacteria produce a toxin in foods such as cream–filled cakes and pies, salads (most at risk are potato, macaroni, egg, and tuna salads, for example) and dairy products. Contaminated potato salad at a picnic is common if the food is not chilled properly.


Bacillus cereus: Causes mild illness with rapid onset of vomiting, with or without diarrhea and abdominal cramping. It is associated with rice (mainly fried rice) and other starchy foods such as pasta or potatoes. May also be used as a potential terrorist weapon.


Escherichia coli (E coli): Causes moderate to severe illness that begins as large amounts of watery diarrhea, and then turns into bloody diarrhea. There are many different types of this bacterium. The worst strain can cause kidney failure and death (about 3–5% of all cases). It is transmitted by eating raw or undercooked hamburger, unpasteurized milk or juices, or contaminated well water. Outbreaks of food poisoning due to E.coli have also occurred following ingestion of contaminated produce.


Shigella (traveler’s diarrhea): Causes moderate to severe illness with fever, diarrhea containing blood or mucus or both, and the constant urge to have bowel movements. It is transmitted in water polluted with human wastes.


Clostridium botulinum (botulism): Causes severe illness affecting the nervous system. Symptoms start as blurred vision. The person then has problems talking and overall weakness. Symptoms then progress to breathing difficulty and inability to move arms or legs. Infants and young children are particularly at risk. It is transmitted in foods such as home–packed canned goods, honey, sausages, and seafood.


Vibrio cholerae: Causes mild to moderate illness with crampy diarrhea, headache, nausea, vomiting, and fever with chills. It strikes mostly in the warmer months of the year and is transmitted by infected, undercooked, or raw seafood.



Parasites rarely cause food poisoning. When they do, they are usually swallowed in contaminated or untreated water and cause long–lasting but mild symptoms.

Giardia (beaver fever): Causes mild illness with watery diarrhea often lasting one to two weeks. It is transmitted by drinking contaminated water, often from lakes or streams in cooler mountainous climates.


Cryptosporidium: Causes moderate illness with large amounts of watery diarrhea lasting two to four days. May become a long–lasting problem in people with poor immune systems (such as people with kidney disease or HIV/AIDS or those on chemotherapy for cancer). It is transmitted by contaminated drinking water.



Toxic agents are the least common cause of food poisoning. Illness is often an isolated episode caused by poor food preparation or selection (such as picking wild mushrooms).

Mushroom toxins: Illness can range from mild to deadly depending on the type of mushroom eaten. Often there is nausea, vomiting, and diarrhea. Some types of mushrooms produce a nerve toxin, which causes sweating, shaking, hallucinations, and coma.


Ciguatera poisoning: Causes moderate to severe illness with numbness of the area around the mouth and lips that can spread to the arms and legs, nausea, vomiting, muscle pain and weakness, headache, dizziness, and rapid heartbeat. It is transmitted by eating certain large game fish from tropical waters—most specifically barracuda and jacks.


Scombroid: Causes mild to moderate illness with burning around the mouth and lips, a red rash to the upper body, dizziness, headache, and itchy skin. It is transmitted in seafood, mostly mahi–mahi and tuna, but can also be in Swiss cheese.


Pesticides: Cause mild to severe illness with weakness, blurred vision, headache, cramps, diarrhea, increased production of saliva, and shaking of the arms and legs. Toxins are transmitted by eating unwashed fruits or vegetables contaminated with pesticides.


When to Seek Medical Care

Contact your doctor if any of the following situations occur:
Nausea, vomiting, or diarrhea lasts for more than two days.
The ill person is younger than three years.
The abdominal symptoms are associated with a low–grade fever.
Symptoms begin after recent foreign travel.
Other family members or friends who ate the same thing are also sick.
You cannot keep any liquids down.
You do not improve within two days even though you are drinking large amounts of fluids.
You have a disease or illness that weakens your immune system (for example, HIV/AIDS, cancer and undergoing chemotherapy, kidney disease).
You cannot take your normal prescribed medications because of vomiting.
You have any nervous system symptoms such as slurred speech, muscle weakness, double vision, or difficulty swallowing.

Go to the nearest hospital's emergency department if any of the following situations occur:
You pass out or collapse, become dizzy, lightheaded, or have problems with your vision.
A fever higher than 101°F occurs with the abdominal symptoms.
Sharp or cramping pains do not go away after 10–15 minutes.
Your stomach or abdomen swells.
The skin and/or eyes turn yellow.
You are vomiting blood or having bloody bowel movements.
You stop urinating, have decreased urination, or have urine that is dark in color.
You develop problems with breathing, speaking, or swallowing.
One or more joints swell or a rash breaks out on your skin.
The ill person or caretaker considers the situation to be an emergency.


Exams and Tests

If you visit a doctor or a hospital emergency department because you think you may have food poisoning, a thorough examination will be performed, including measurements of blood pressure, pulse, breathing rate, and temperature will be done. The doctor will perform a physical exam, which screens for outward signs and symptoms of your illness. They will assess how dehydrated you are and examine your abdominal area to make sure your illness is not serious.
The doctor may need to do a rectal examination. The doctor performs this test by inserting a lubricated and gloved finger gently into your rectum. The purpose is to make sure there are no breaks in your rectal wall. A sample of your stool is taken and tested for blood and mucus. In some cases, a sample of stool or vomit can be sent to the laboratory for further testing to find out which toxin caused the illness. In a majority of cases, a specific cause is not found.


A urine sample helps assess how dehydrated you are and indicates possible kidney damage.


Blood tests may be performed to determine the seriousness of your illness. An x–ray of the abdomen or a CT scan may be taken if the doctor suspects your symptoms may be caused by another illness.


Food Poisoning Treatment

Self–Care at Home

Short episodes of vomiting and small amounts of diarrhea lasting less than 24 hours can usually be cared for at home.

Do not eat solid food while nauseous or vomiting but drink plenty of fluids.

Small, frequent sips of clear liquids (those you can see through) are the best way to stay hydrated.

Avoid alcoholic, caffeinated, or sugary drinks, if possible. Over–the–counter rehydration products made for children such as Pedialyte and Rehydralyte are expensive but good to use if available.

Sports drinks such as Gatorade and Powerade are fine for adults if they are diluted with water because at full strength they contain too much sugar, which can worsen diarrhea.

After successfully tolerating fluids, eating should begin slowly, when nausea and vomiting have stopped. Plain foods that are easy on the stomach should be started in small amounts. Consider eating rice, wheat, breads, potatoes, cereals (low–sugar cereals), lean meats, and chicken (not fried) to start. Milk can be given safely, although some people may experience additional stomach upset due to lactose intolerance.

Most food poisonings do not require the use of over–the–counter medicines to stop diarrhea, but they are generally safe if used as directed. It is not recommended that these medications be given to children. If there is a question or concern, you should always check with your doctor.


Medical Treatment

The main treatment for food poisoning is putting fluids back in the body (the process of rehydration) through an IV and by drinking. You may need to be admitted to the hospital. This depends on the severity of the dehydration, your response to therapy, and your ability to drink fluids without vomiting. Children, in particular, may need close observation.
Antivomiting and diarrhea medications may be given.
The doctor may also treat any fever to make you more comfortable.
Antibiotics are rarely needed for food poisoning. In some cases, antibiotics would worsen the condition. Only a few specific causes of food poisoning are improved by using these medications. The length of illness with traveler's diarrhea (shigellae) can be decreased with antibiotics, but this specific illness usually runs its course and improves without treatment.
With mushroom poisoning or eating foods contaminated with pesticides, aggressive treatment may include pumping the stomach (lavage) or giving medications as antidotes. These poisonings are very serious and may require intensive care in the hospital.


Next Steps

Follow–up

After visiting your doctor or the emergency department, follow any specific directions and take any medications prescribed exactly as directed. Continue to drink extra fluids until the diarrhea stops completely. You may need to miss one to two days of work or school to let your body recover. If any symptoms change or continue to worsen, contact your doctor.


Prevention

Safe steps in food handling, cooking, and storage are essential to avoiding food–borne illness. You cannot see, smell, or taste bacteria, which may be on any food.

Follow these food safety guidelines to keep contaminants away.
Safe shopping

Buy cold foods last during your shopping trip. Get them home fast.


Never choose torn or leaking packages.


Do not buy foods past their "sell–by" or expiration dates.


Keep raw meat and poultry separate from other foods.


Place refrigerated or frozen items in the shopping cart last, right before heading for the checkout counter.


Safe storage of foods

Keep it safe; refrigerate.


Unload perishable foods first and immediately refrigerate them. Place raw meat, poultry, or fish in the coldest section of your refrigerator.


Check the temperature of your appliances. To slow bacterial growth, the refrigerator should be at 40°F, the freezer at 0°F.


Cook or freeze fresh poultry, fish, ground meats, and variety meats within two days.

Safe food preparation

Keep everything clean!


Wash hands before and after handling raw meat and poultry.


Sanitize cutting boards often in a solution of one teaspoon chlorine bleach in one quart of water.


Do not cross–contaminate. Keep raw meat, poultry, fish, and their juices away from other food. After cutting raw meats, wash hands, cutting board, knife, and counter tops with hot, soapy water.


Marinate meat and poultry in a covered dish in the refrigerator. Discard any uncooked/unused marinade.

Thawing food safely

Refrigerator: Allows slow, safe thawing. Make sure thawing juices do not drip on other foods.


Cold water: For faster thawing, place food in a leak–proof plastic bag and submerge in cold tap water.


Microwave: Cook meat and poultry immediately after microwave thawing.


Safe cooking

Use a meat thermometer.


Cook ground meats to 160°F; ground poultry to 165°F. Beef, veal, and lamb steaks, roasts and chops may be cooked to 145°F; all cuts of fresh pork, 160°F. Whole poultry should reach 180°F in the thigh; breasts 170°F.


Keep hot foods hot and cold foods cold.


Never leave food out more than two hours (or more than 1 hour in temperatures above 90°F).


Bacteria that cause food poisoning grow rapidly at room temperature.


Use cooked leftovers within four days.