Food Poisoning

Foodborne illness (or food poisoning) is a common, distressing and sometimes life-threatening problem for millions of people in the United States and around the world. People infected with foodborne organisms may be symptom-free or may develop symptoms ranging from mild intestinal discomfort to severe dehydration, bloody diarrhea, or-- in more serious and untreated cases--even death. The two most common forms of foodborne illness are Salmonella and Campylobacter infections. More than 250 different diseases have been identified that can be caused by contaminated food or drink. The most common diseases are infections caused by bacteria, such as Salmonella and Campylobacter. The majority of food items that cause foodborne diseases are raw or undercooked foods from animal sources, such as meat, milk, eggs, cheese, fish or shellfish. Brief overviews of the more common foodborne diseases follow.

• Campylobacter infections
• Salmonella
• Shigella
• E.coli
• Listeria
• Botulism

Campylobacter infections

Cause
Campylobacter has been recognized as the leading cause of chronic diarrhea in the United States, and is found predominantly in industrialized countries. Most frequently cattle and poultry are the sources of human infection, but puppies, kittens, pigs, sheep, rodents, and birds may also serve as carriers. Transmission usually occurs through ingestion of contaminated food, water or un-pasteurized milk, or through contact with infected infants, pets, or wild animals.

Symptoms
Campylobacter is characterized by diarrhea (sometimes bloody), nausea, vomiting, malaise, and fever. The illness typically lasts one week. While some Campylobacter infections do not have symptoms, others may result in arthritis and rarely, meningitis or convulsions with fever.

Associated problems
Infection with Campylobacter also can be associated with the development of Guillain-Barre syndrome (GBS), the leading cause of acute paralysis in the United States. GBS develops in a small number of people two to four weeks after becoming infected with the Campylobacter bacteria, usually after diarrhea symptoms have gone away. GBS is characterized by progressive paralysis of the limbs, and in more severe cases, by development of respiratory failure requiring prolonged hospitalization.

Diagnosis
Physicians can identify Campylobacter bacteria by testing a stool sample. Diagnosis of Campylobacter requires special laboratory culture procedures, which a physician would need to request.

Treatment
Generally, most people will recover completely within 2 to 5 days and no treatment is needed. You should drink plenty of fluids to counter the dehydration from diarrhea. In more severe cases, antibiotics such as erythromycin or fluoroquinone can be used, and can shorten the length of time you are sick if they are given early in the illness. Antidiarrhea medications, such as loperamide (Imodium), should also be avoided.

Prevention
See general guidelines.

Salmonella

Causes
Salmonella is an invasive organism that can escape from the intestine and be carried in the blood to other organs. It can become a chronic infection in some people, who can be symptom-free yet capable of spreading the disease to others. Ordinarily, deaths are uncommon except in those who are very young, elderly, or have weakened immune systems.

Salmonellosis (the disorder caused by Salmonella) occurs worldwide, but it is most extensively reported in North America and Europe, with cases on the rise each year. Only a small proportion of infected people are tested and diagnosed, with as few as 1 percent of cases reported. Salmonellosis may occur in small, localized outbreaks in the general population or in large outbreaks in hospitals, restaurants or institutions for children or the elderly.

Domestic and wild animals, including poultry, pigs, cattle, and pets (including turtles, iguanas, chicks, dogs, and cats) can harbor the Salmonella bacterium. Although pets may have no symptoms, they can pass on the infection to humans. Salmonellosis is caused most often by drinking non-pasteurized milk or by eating undercooked poultry and poultry products including eggs. Any food prepared on surfaces exposed to raw chicken or turkey can become contaminated. Less often, the illness may stem from food contaminated by a food worker.

Symptoms
The disease causes acute intestinal distress with sudden onset of headache, fever, abdominal pain, diarrhea, nausea, and sometimes vomiting. These symptoms, along with loss of appetite, can persist for several days. Dehydration, especially in infants, can be severe.

Other complications
People with salmonella usually recover completely, although it may take several months before bowel habits are entirely normal. A small proportion of people who are infected with salmonella will go on to develop pain in their joints, irritation of the eyes, and painful urination. This is called Reiter's syndrome. It can last for months or years, and can lead to arthritis, which is difficult to treat. Antibiotic treatment does not make a difference in whether the person later develops arthritis.

Diagnosis
After assessing your symptoms, a physician may order a laboratory test to identify Salmonella in your stool. These tests are generally not performed unless the laboratory is instructed specifically to look for the organism. If salmonella is identified, further testing will be done to determine its specific type and whether antibiotics are needed.

Treatment
Salmonella infections usually go away in 5 to 7 days. The infections often do not require treatment unless the patient becomes severely dehydrated or the infection spreads outside of the intestines. People with severe diarrhea may require re-hydration, often with intravenous fluids. Antibiotics are not usually necessary unless the infection spreads through the bloodstream into other organs. In these cases, the infection can be treated with ampicillin, gentamicin,amethoxazole, or ciprofloxacin. Unfortunately, some Salmonella bacteria have become resistant to antibiotics.

Prevention
Wash your hands with soap after contact with reptiles, birds, or pet feces. Very young children and people with weakened immune systems should avoid ANY contact with reptiles.

Also see general prevention guidelines.

Shigella

Causes
Shigellosis, also called bacillary dysentery, causes more than 30,000 cases of foodborne illness in the United States each year. Outbreaks generally occur in tropical or temperate climates and are more likely in conditions where there is crowding or personal hygiene is poor. Shigella organisms are generally transmitted through feces. Good personal hygiene and proper food preparation procedures are imperative in controlling infection with Shigella.

Symptoms
Shigellosis causes bloody diarrhea, fever, nausea, vomiting, and cramps.

Diagnosis
Physicians can identify Shigella bacteria through a stool sample from an ill person. Diagnosis of shigellosis requires special laboratory culture procedures, which a physician would need to request.

Treatment
Treatment for shigellosis is rarely needed, and symptoms should go away within a few days. Drinking fluids to prevent dehydration is probably the best course of action.

Prevention
Bacteria from stools of infected people can be passed from one person to another if hygiene or hand-washing habits are inadequate. This is particularly likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of becoming infected. Young children typically shed the organism in their feces for a week or two after their symptoms go away.

Enterohemorrhagic Escherichia coli infection (E. coli)

Cause
E. coli (O157:H7) is an emerging cause of foodborne illness. Most E. coli infections have been associated with eating undercooked, contaminated ground beef. The organism that causes E. coli can be found on a small number of cattle farms and can live in the intestines of healthy cattle. Meat can become contaminated during slaughter, and E. coli organisms can be thoroughly mixed into beef when it is ground. Bacteria present on the cow's udders or on equipment may get into raw milk. Eating meat--especially ground beef--that has not been cooked sufficiently to kill E. coli can cause infection. Contaminated meat looks and smells normal.

Drinking non-pasteurized milk and swimming in or drinking sewage-contaminated water can also cause infection. Bacteria from stools of infected people can be passed from one person to another if hygiene or hand-washing habits are inadequate. This is particularly likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of becoming infected. Young children typically shed the organism in their feces for a week or two after their illness resolves.

Symptoms
The E. coli infection causes severe bloody diarrhea and abdominal cramps. Sometimes, the infection causes non-bloody diarrhea, a slight fever, or no symptoms at all.

In some people, particularly children under age five and the elderly, the infection can cause a complication called hemolytic uremic syndrome, in which the red blood cells are destroyed and the kidneys fail. About 2 to 7 percent of infections lead to this complication.

Hemolytic uremic syndrome is a life-threatening condition usually treated in an intensive care unit. Blood transfusions and kidney dialysis are often required. With intensive care, the death rate for hemolytic uremic syndrome is only 3 to 5 percent.

Diagnosis
In addition to the symptoms, E. coli is diagnosed by detecting the bacterium in the stool. Most laboratories that culture stool do not test for E. coli, so it is important for your physician to request that the stool specimen be tested for this organism. All persons who have sudden diarrhea with blood should get their stool tested for E. coli.

Treatment
Most people recover without antibiotics or other specific treatment in 5 to 10 days. There is no evidence that antibiotics improve the course of disease, or that treatment with some antibiotics may intensify kidney complications. Antidiarrheal medications, such as loperamide (Imodium), should also be avoided.

Prevention
You can prevent E. coli infection by thoroughly cooking ground beef, avoiding non-pasteurized milk, and washing your hands carefully after handling meat or using the bathroom. Because the organism lives in the intestines of healthy cattle, preventive measures on cattle farms and during meat processing are being investigated.

Listeria

Risks
Healthy adults and children occasionally get infected with the Listeria bacterium, but they rarely become seriously ill. Those at increased risk for developing listeriosis include the following:

• Pregnant women — Pregnant women are about 20 times more likely than other healthy adults to get listeriosis. About one third of listeriosis cases happen during pregnancy. Newborns suffer the serious effects of listeriosis infection when their mothers are infected during pregnancy.
• People with weakened immune systems
• People with cancer, diabetes or kidney disease
• People with AIDS — These individuals are almost 300 times more likely to get listeriosis than people with normal immune systems.
• People who take glucocorticosteroid medications
• The elderly

Causes
Listeria is primarily found in soil and water. Vegetables can become contaminated from soil or from manure used as fertilizer. Animals can carry the bacterium without appearing ill and can contaminate food. The bacterium has been found in a variety of uncooked foods, such as meats and vegetables, as well as in processed foods that become contaminated after processing, such as soft cheeses and cold cuts.

Non-pasteurized milk or foods made from un-pasteurized milk may contain the bacterium. Listeria is killed by pasteurization, and heating procedures used to prepare ready-to-eat processed meats should be sufficient to kill the bacterium. However, unless good manufacturing practices are followed, contamination can occur after processing.

Symptoms
The symptoms of Listeria infection include fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur.

Infected pregnant women may experience only a mild, flu like illness; however, infection during pregnancy can lead to premature delivery, infection of the newborn, or even stillbirth. There is no routine screening test to find out if you are likely to contract Listeria infection during pregnancy, as there is for rubella and other congenital infections. If you have symptoms such as fever or stiff neck, consult your doctor. A blood or spinal fluid test (to cultivate the bacteria) will show if you have listeriosis. During pregnancy, a blood test is the most reliable way to find out if you are infected.

Treatment
When infection occurs during pregnancy, antibiotics given promptly to the pregnant woman can often prevent infection of the fetus or newborn. Babies with listeriosis receive the same antibiotics as adults, although a combination of antibiotics is often used until physicians are certain of the diagnosis.

Even with prompt treatment, some infections result in death. In the elderly and people with other serious medical problems, these infections are more likely to be fatal.

Botulism

Cause
Botulism is a rare but serious foodborne disease caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. There are three main types of botulism: foodborne, wound, and infant. Foodborne botulism is caused by eating foods that contain the botulism toxin. Wound botulism, which is very rare, is caused by toxin produced from a wound infected with Clostridium botulinum. Infant botulism is caused by consuming the spores of botulinum bacteria, which grow in a child's intestines and release toxin. All forms of botulism can be deadly and are considered medical emergencies.

Symptoms
The most common symptoms of botulism include blurred vision, double vision, droopy eyelids, slowed or slurred speech, difficulty swallowing, dry mouth and muscle weakness. In infants with botulism the symptoms include poor feeding habits, constipation, weak crying, lethargy and poor muscle tone. These are all symptoms of the muscle paralysis caused by the toxin from the Clostridium botulinum bacteria. If these symptoms are untreated, they may lead to paralysis of the arms, legs, trunk and respiratory muscles. Symptoms from foodborne botulism, usually develop between 18 to 36 hours after consuming contaminated food, but symptoms can occur as early as six hours or as late as a week.

Diagnosis
Diagnosis is made by presence of appropriate neurologic symptoms and by laboratory tests that detect the toxin or by culture of Clostridium botulinum from the patients stool.

Treatment
The respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks, plus intensive medical and nursing care in a hospital. After several weeks the paralysis slowly improves. If diagnosed in its early stages, foodborne botulism can be treated with an antitoxin that blocks the toxin circulating in the blood. This can prevent a patient's condition from worsening, but recovery will still require a few weeks of rest and observation. Physicians may also try to remove any contaminated food left in the digestive system by inducing vomiting or by using enemas. Treatment for infants requires hospitalization and possibly care in an intensive care unit. The botulism antitoxin is not recommended for infants.

Prevention
Although there are very few cases of botulism poisoning each year, prevention is extremely important. Foodborne botulism has often been linking to home-canned foods with low acid content, such as asparagus, green beans, beets and corn. Cases have also been reported from more unusual sources such as chopped garlic in oil, chile peppers, tomatoes, improperly handled baked potatoes cooked in aluminum foil and home canned or fermented fish (such as sardines). Persons who home can should follow strict hygienic procedures to reduce contamination of foods. Because the botulism toxin is destroyed by high temperatures, person who eat home-canned food should boil the food for 10 minutes to ensure safety. Instructions on safe home canning can be obtained from the US Department of Agriculture (http://www.foodsafety.org/canhome.htmor www.usda.gov). Oils infused with garlic or herbs should be kept refrigerated. Potatoes that have been wrapped in aluminum foil while baking should be kept hot until they are served or refrigerated.

Because honey can contain spores of Clostridium botulinum, which has been a source of infection for infants, children less than 12 months old should not be fed honey. Honey is safe for persons 1 year of age and older.

How can I prevent foodborne illnesses?

General guidelines
Make sure that food from animal sources (meat, dairy, eggs) is cooked thoroughly or pasteurized. Avoid eating these foods raw or undercooked. Check expiration dates on meats before purchasing and again before preparing.

Carefully select and prepare fish and shellfish to ensure quality and freshness.

If you are served an undercooked meat or egg product in a restaurant, send it back for further cooking. You should also ask for a new plate.

Be careful to keep juices or drippings from raw meat, poultry, shellfish or eggs, from contaminating other foods.

Do not leave foods like eggs, meats, poultry, seafood, or milk, for extended periods of time at temperatures that permit bacteria to grow. Promptly refrigerate leftovers and food that is prepared in advance.

Wash your hands, cutting boards, and knives with antibacterial soap and warm to hot water after handling raw meat, poultry, seafood, or eggs. Do not use wooden cutting boards. Even when these cutting boards are thoroughly cleaned, they provide an environment where bacteria can grow.

Avoid raw (non-pasteurized) milk or foods made from raw milk.

Do not thaw foods at room temperature. Thaw foods in the refrigerator and use them promptly. Do not refreeze foods once they have been completely thawed.

Wash raw vegetables and fruits thoroughly before eating. Children under five years of age, people with weakened immune systems, and the elderly should avoid eating alfalfa sprouts until their safety can be assured. Methods to decontaminate alfalfa seeds and sprouts are being investigated.

Drink only pasteurized juice or cider. Commercial juice with an extended shelf life that is sold at room temperature (juice in cardboard boxes, vacuum sealed juice in glass containers) has been pasteurized, although this is generally not indicated on the label. Juice concentrates are also heated sufficiently to kill pathogens.

If you are ill with diarrhea or vomiting, do not prepare food for others--especially infants, the elderly, and those with weakened immune systems.

Mother's milk is the safest food for young infants. Breastfeeding prevents many foodborne illnesses and other health problems.

Guidelines for special populations
People at high risk for infection (pregnant women, people with weakened immune systems, infants, and the elderly) should do the following:

• Avoid soft cheeses such as feta, Brie, Camembert, blue-veined, and Mexican-style cheese. (Hard cheeses, processed cheeses, cream cheese, cottage cheese, or yogurt are safe.)
• Cook foods until they are steaming hot, especially leftover foods or ready-to-eat foods, such as hot dogs, before eating.

Although the risk of foodborne disease associated with foods from deli counters is relatively low, pregnant women and people with weakened immune systems may choose to avoid these foods or thoroughly reheat cold cuts before eating.

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 3/15/2005