Food
poisoning, or intoxication, is a group of disorders generally characterized by the symptoms of nausea, vomiting, and
loss of appetite (anorexia); fever and abdominal pain or discomfort (gastroenteritis); and diarrhea, in varying degrees. It may result from poisons, or toxins, produced by microorganisms in food; ingestion of heavy metals such as copper and mercury; and ingestion of natural poisons such as those found in some mushrooms and seafood. The Centers for Disease Control and Prevention (CDC) estimates that between 6 and 80 million cases of food-related illness occur annually in the United States. Many food poisonings go unreported, because most cases pass within a week, with few aftereffects.
Microorganisms
Campylobacter jejuni, a bacteria found in most poultry, is by far the most common cause of food
poisoning, with a CDC estimate of at least 4 million cases each year. Symptoms of nausea, vomiting, gastrointestinal discomfort, and fever may appear 2 to 5 days after eating undercooked chicken or drinking unpasteurized milk or
contaminated water.
The second most common bacterial food poisoning, with over 2 million cases annually, is caused by Salmonella, commonly found in meats, eggs, and milk. Symptoms appear 12 to 48 hours after eating contaminated food.
Certain rare strains of the bacteria Escherichia coli can cause food poisoning in young children, the elderly, and people with impaired immune systems. E. coli 0157:H7, normally found in the intestines and fecal matter of humans and animals, can survive in meat if the meat is not cooked past 155¡ F. A 1993 U.S. outbreak of this type of food poisoning, which affected over 450 people, was attributed to contaminated hamburgers that were cooked rare.
If food contaminated by the bacterium Clostridium botulinum is improperly canned or bottled, the bacteria are able to produce a toxin, which produces the disease botulism. The botulin toxin is absorbed and, within 8 to 36 hours after ingestion of the contaminated food, acts by paralyzing certain nerves that regulate muscle function. This results in respiratory failure, as the muscles that control breathing weaken. The mortality rate can be as high as 65 percent, with most fatalities occurring between the second and ninth day after ingestion of the toxin. Recovery is slow in survivors. Potent antitoxins, prepared from the plasma of horses, are most effective before the patient shows symptoms.
Diarrhea and vomiting may result from infection by the protozoan Entamoeba histolytica, acquired by eating uncooked vegetables or drinking contaminated water (amoebic dysentery). This food-borne infection usually develops within 12 to 48 hours of ingesting the protozoan. The loss of fluids resulting from diarrhea and vomiting can lead to dehydration, which can threaten the life of young or elderly patients. Treatment includes bed rest, fluids, and blood or plasma expanders if shock is impending.
Metals
Ingestion of heavy metals, such as lead and mercury, can cause acute nausea, vomiting, and diarrhea and may cause respiratory or nervous system damage over the long term. The severity of the symptoms depends on the irritant and the dose, as well as the resistance of the patient. Treatment includes bed rest, fluids, and blood or plasma expanders in severe cases where shock is anticipated.
Natural Poisons
The ingestion of naturally occurring poisons is involved in mushroom, or toadstool, poisoning; fish poisoning; shellfish poisoning; and poisoning from contaminants. Mushroom poisoning, from mushrooms such as Amanita phalloides or muscaria, can result in the symptoms of sweating, cramps, diarrhea, confusion, and sometimes convulsions. Patients usually recover within 24 hours. If the infecting mushroom is A. phalloides, however, liver damage is common, leading to jaundice; remissions may occur, but the mortality rate is about 60 percent or higher.
Fish poisoning can result from Pacific types such as sea bass, Caribbean types such as cavallas, Scrombroid types such as mackerel, and Tetraodon types such as puffers. Symptoms include numbness of the limbs, joint aches, chills, and fever. Muscle weakness and paralysis can also occur, and death may result within 24 hours. Mussels and clams may ingest a poisonous dinoflagellate (red tide) from June to October that produces a toxin not destroyed by cooking. Symptoms include nausea, vomiting, and abdominal cramps, and death can occur as a result of respiratory failure.