Food Poisoning

Food poisoning is a general term for a variety of illnesses occurring after a person has eaten food contaminated by certain types of bacteria; these bacteria either directly damage tissue or create toxins with far-reaching effects. Food poisoning often provokes a combination of intestinal symptoms: nausea, vomiting, abdominal cramps, and diarrhea; headache or fever may also occur, depending on the bacteria involved. One food-borne illness—botulism—affects the central nervous system and is sometimes life-threatening.

Very often food poisoning looks and feels like common viral gastroenteritis (stomach flu), and the only due that food is the cause may be the simultaneous eruption of similar symptoms among family members or friends, especially if these people recently shared a meal or ate at the same restaurant. Unfortunately, food contaminated by these bacteria does not necessarily look, smell, or taste any different from uncontaminated food. As a result food poisoning usually catches its victims by surprise.

Staphylococcal food poisoning is the most common and often the most unpleasant food-related illness; fortunately it is the most short-lived. Staphylococci (“staph” for short) are best known for causing skin infections such as boils and impetigo. Someone with an infected wound or sore on the hands might introduce staph into food. If the food is warm—not hot or cold but about 100°F—the bacteria will multiply and produce a toxin that is resistant to cooking. (This is an important reason why warm foods should not sit for long periods of time. They should either be kept hot or directly refrigerated.)

Symptoms of staphylococcal food poisoning begin abruptly less than six hours after the meal and set off a combination of intense vomiting (usually the worst symptom), diarrhea, and severe abdominal cramps. The illness will end within 24 hours without specific treatment.

Campylobacter bacteria colonize wild, domestic and raw animals, especially poultry. Undercooked chicken, turkey, and waterfowl are common food sources for these bacteria, along with raw (unpasteurized) milk. Campylobacter infections begin with flulike symptoms: high fever and headache, nausea, vomiting, and abdominal cramps. Then comes diarrhea: frequent (up to twenty stools per day), usually watery, mucoid (containing mucus), or even bloody. Usually the illness subsides on its own but relapses are possible. If a stool test identifies campylobacter as the cause of illness, appropriate antibiotic treatment will shorten the duration of the symptoms as well as the shedding of bacteria, which might infect someone else. (Outbreaks in day-care centers have been reported.)

Salmonella are bacteria that can cause not only food poisoning but more serious, widespread infections (especially in newborns and infants), as well as typhoid fever. While typhoid is far less common in North America than in developing countries, salmonella food poisoning has been on the rise over the past two decades. Animals, especially fowl and reptiles, are carriers of many salmonella species but do not transmit the specific form that causes typhoid.

Meats, dairy products (including ice cream), undercooked eggs, and contaminated egg products used in other foods (such as custards and mayonnaise) can contain salmonella. One or two days after ingestion, fever, vomiting, and diarrhea begin. Older children may complain of a headache and abdominal cramps. If all goes well, symptoms resolve in a few days without treatment. In fact, a child who is stable and showing no other signs of trouble probably should not be given antibiotics for salmonella food poisoning because these drugs may prolong the time that the bacteria remain in the intestinal tract.

Of all the bacteria that cause food poisoning, salmonella is the most likely to enter the bloodstream (although this is rare), through which it can travel and infect bones, kidneys, heart, lungs, or joints. Salmonella can also cause meningitis if it infects the linings around the brain and spinal cord.

Since widespread salmonella can be a serious problem, infants younger than three months of age, as well as children with chronic medical problems (such as sickle-cell disease, immune deficiency, or heart or kidney disease) should be treated with appropriate antibiotics if these bacteria are isolated from their stool. Young infants or children who are severely ill with salmonella will require treatment in the hospital with intravenous fluids and antibiotics.

Salmonella is known for its capacity to remain in the intestinal tract for weeks or even months after the acute symptoms are gone. The child in this “carrier state” won’t be ill but can spread the bacteria to others, even after receiving antibiotics. Careful hand washing by adult caregivers and by the child himself (if he’s old enough) is extremely important in the wake of a salmonella infection.

E. coil normally live in the intestinal tract of humans without causing disease, but some strains are associated with a variety of diarrhea syndromes. A common form is mild but annoying traveler’s diarrhea, which normally resolves on its own. Other forms are more serious and are accompanied by fever, cramping, and bloody diarrhea. (E. coli species are also commonly involved in urinary tract infections, and in infants they may cause meningitis or other serious illness. Most of these occur independently of the diarrhea syndromes. One subtype can cause a serious combination of kidney failure, anemia, and clotting problems known as hemolytic-uremic syndrome. These particular bacteria and other dangerous forms of E. coli are known to contaminate ground beef and other foods.

Two distinct types of infections are caused by species of the bacteria called clostridium. Clostridium perfringens resides in soil, sewage, and the intestines of humans and animals. It is best known for contaminating food produced in large quantities, such as that cooked in restaurants, institutional kitchens, or school cafeterias, where food may sit for hours slightly warm or at room temperature. Stews, casseroles, and gravies are particularly prone to transmit this organism. Symptoms are unpleasant—abrupt onset of vomiting and explosive diarrhea—but normally resolve without specific treatment within a few days.

Clostridium botulinum is another story. This bacterium produces a potent toxin that causes botulism, but only under conditions in which there is no oxygen plus the right mix of chemicals. This contamination can occur within improperly canned foods such as corn, beets, peas, and green beans, as well as in honey contaminated with clostridium botulinum spores. Unlike other food poisonings, botulism affects the central nervous system. After an 8- to 36-hour incubation, fatigue and headache begin, followed by visual symptoms (droopy eyelids, double vision, dilated pupils). A few hours later, swallowing and speech may be affected. Paralysis can develop, and if muscles necessary for breathing are affected, respiratory failure and death could follow.

Infant botulism often occurs when babies under twelve months of age are given contaminated honey. They become constipated and lethargic, with a weak suck and cry, floppy muscle tone, and in some cases sudden failure to breathe (apnea).

A specific antitoxin can be given with food once the diagnosis is made, but long-term care, including intravenous or tube feeding and support using a ventilator, might be necessary for several weeks. Botulism is less likely to be fatal in children than in adults. Without a doubt this is an illness that you want your child to avoid.