CHAPTER 21
Gastroenteritis
Gastroenteritis is inflammation of the lining of the stomach and small and large intestines. It is usually caused by infection with a microorganism but can also be caused by ingestion of chemical toxins or drugs.
The infection is usually caused by an infection but can be caused by ingesting toxins or drugs.
Typically, people have diarrhea, nausea, vomiting, and abdominal pain.
The diagnosis is based on some laboratory tests and a person’s history of recent contact with contaminated people, food, or water or antibiotic use.
Thoroughly washing the hands after a bowel movement or contact with fecal matter is the best way to prevent infection.
Antibiotics are used to eliminate only certain kinds of bacteria.
Gastroenteritis usually consists of mild to severe diarrhea that may be accompanied by loss of appetite, nausea, vomiting, cramps, and discomfort in the abdomen. Although gastroenteritis usually is not serious in a healthy adult, causing only discomfort and inconvenience, it can cause life-threatening
MICROORGANISMS THAT CAUSE GASTROENTERITIS
dehydration (see page 970) and electrolyte imbalance (see page 933) in the very ill or weak, the very young, and the very old. About 3 to 6 million children around the world die each year from infectious gastroenteritis.
Causes
Infections that cause gastroenteritis can be transmitted from person to person, especially if people with diarrhea do not thoroughly wash their hands after a bowel movement. Infection also can occur if people touch their mouth after touching an object (such as a diaper or toy) contaminated by infected stool. All such transmission involving infected stool is termed fecal-oral transmission. A person, and sometimes large numbers of people (in which case an outbreak of illness is called an epidemic), can also become infected by eating food or drinking water that has been contaminated by infected stool. Most foods can be contaminated with bacteria and cause gastroenteritis if not cooked thoroughly or pasteurized. Contaminated water is sometimes ingested in unexpected ways, such as when swimming in a pond contaminated by stool from an animal or in a swimming pool contaminated by stool from another person. In some cases, gastroenteritis is acquired through contact with animals that carry the infectious microorganism.
Did You Know…
Worldwide, about 3 to 6 million children die each year from gastroenteritis caused by an infection.
Infectious gastroenteritis may be caused by viruses, bacteria, or parasites. Chemical toxins and drugs can also cause gastroenteritis.
Viruses: Viruses are the most common cause of gastroenteritis in the United States. Certain viruses infect cells in the lining of the small intestine where they multiply and cause watery diarrhea, vomiting, and fever. Four categories of viruses cause most gastroenteritis: rotavirus, calicivirus (predominantly the norovirus), and less commonly, astrovirus, and enteric (intestinal) adenovirus.
Rotavirus (see page 1782) is the most common cause of severe, dehydrating diarrhea among young children. It usually affects those between the ages of 3 months and 15 months. Rotavirus is highly contagious. Most infections are spread by fecal-oral transmission. Adults may be infected after close contact with an infected infant, but the illness is generally mild. During the winter in temperate climates, rotavirus causes most cases of diarrhea that are serious enough to send infants and toddlers to the hospital. Each year in the United States, a wave of rotavirus illness begins in the Southwest in November and ends in the Northeast in March.
Norovirus most commonly infects older children and adults. Infections occur year-round. Most people are infected after swallowing contaminated food or water. Because norovirus is highly contagious, infection can easily be spread from person to person.
Astrovirus can infect people of all ages but usually infects infants and young children. Infection is most common in the winter and is spread by fecal-oral transmission.
Adenovirus most commonly affects children under the age of 2. Infections occur year-round and increase slightly in the summer. The infection is spread by fecal-oral transmission.
Other viruses (such as cytomegalovirus and enterovirus) can cause gastroenteritis in people who have an impaired immune system.
Bacteria: Bacterial gastroenteritis is less common than viral gastroenteritis.
Some bacteria (such as certain strains of Escherichia coli [E. coli], Campylobacter, Shigella, and Salmonella) invade the lining of the small intestine or colon. There, they damage cells, causing tiny sores (ulcerations) that bleed, and allow a considerable leakage of fluid containing proteins, electrolytes, and water. The diarrhea contains white and red blood cells and sometimes visible blood.
Salmonella and Campylobacter are the most common bacterial causes of diarrhea in the United States. Both infections are most frequently acquired from undercooked poultry. Unpasteurized milk is also a possible source. Campylobacter is occasionally transmitted by dogs or cats with diarrhea. Salmonella can be transmitted by undercooked eggs and by having contact with reptiles (such as turtles or lizards).
Species of Shigella are the third most common bacterial cause of diarrhea in the United States and are usually transmitted person to person, although food-borne epidemics occur.
Several different subtypes of E. coli cause diarrhea. Enterohemorrhagic E. coli is the most significant subtype of E. coli in the United States and causes hemorrhagic colitis (see page 150) and sometimes hemolytic-uremic syndrome (see page 1042). The strain E. coli O157:H7 is the most common strain of this subtype in the United States. Undercooked ground beef, unpasteurized milk and juice, and contaminated water are possible sources. Person-to-person transmission is common in day care centers. Another subtype of E. coli (called enterotoxigenic E. coli) produces two toxins that cause watery diarrhea. This subtype is the most common cause of traveler’s diarrhea (see page 152). A third subtype of E. coli also causes watery diarrhea. It was once a common cause of diarrhea outbreaks in nurseries but is now rare. A fourth subtype of E. coli causes bloody or nonbloody diarrhea, primarily in developing countries. It is rare in the United States.
Other bacteria (such as Staphylococcus aureus, Bacillus cereus, and Clostridium perfringens) produce a toxin that can be present in contaminated food. The toxin can cause gastroenteritis without causing a bacterial infection. These toxins generally cause severe nausea, vomiting, and diarrhea. Symptoms begin within 12 hours of ingestion of contaminated food and lessen within 36 hours.
Several other bacteria cause gastroenteritis, but most are rare in the United States. Yersinia enterocolitica can cause gastroenteritis or a syndrome that mimics appendicitis. A person is infected after ingesting undercooked pork, unpasteurized milk, or contaminated water. Several Vibrio species (such as Vibrio parahaemolyticus) cause diarrhea after ingestion of undercooked seafood. Vibrio cholerae, which is responsible for the watery diarrhea that is the main symptom of cholera, sometimes causes severe dehydrating diarrhea in developing countries. Listeria causes food-borne gastroenteritis. Aeromonas is acquired from swimming in or drinking contaminated fresh water or briny, salty water. Plesiomonas shigelloides can cause diarrhea in people who have eaten raw shellfish or traveled to tropical regions in developing countries.
Parasites: Certain intestinal parasites, particularly Giardia lamblia, stick to or invade the lining of the intestine and cause nausea, vomiting, diarrhea, and a general sick feeling. The resulting infection, called giardiasis, is more common in cold climates but occurs in every region of the United States and throughout the world. If the disease becomes persistent (chronic), it can keep the body from absorbing nutrients, a condition known as a malabsorption syndrome. Infection is usually spread through person-to-person contact (often in day care centers) or from contaminated water.
Another intestinal parasite, called Cryptosporidium parvum, causes watery diarrhea that is sometimes accompanied by abdominal cramps, nausea, and vomiting. The resulting infection, called cryptosporidiosis, is usually mild in otherwise healthy people, but it may be severe or even fatal in people with a weakened immune system. It is most commonly acquired by drinking contaminated water.
Other parasites that can cause symptoms similar to those of cryptosporidiosis include Cyclospora cayetanensis and, in people with an impaired immune system, Isospora belli and a collection of organisms referred to as microsporidia. Entamoeba histolytica causes amebiasis, an infection of the large intestine and sometimes the liver and other organs. Amebiasis is a common cause of bloody diarrhea in developing countries and occasionally occurs in the United States.
Chemical Gastroenteritis: Gastroenteritis may result from ingesting chemical toxins. These toxins are usually produced by a plant, such as poisonous mushrooms, or by certain kinds of exotic seafood and thus are not the product of an infection. Gastroenteritis due to chemical toxicity can also occur after ingesting water or food contaminated by chemicals such as arsenic, lead, mercury, or cadmium. Heavy-metal poisoning frequently causes nausea, vomiting, abdominal pain, and diarrhea. Eating large amounts of acidic foods, such as citrus fruits and tomatoes, gives some people gastroenteritis.
Gastroenteritis as a Side Effect of Drugs
Nausea, vomiting, and diarrhea are common side effects of many drugs. Common culprits include antacids containing magnesium as a major ingredient, antibiotics, chemotherapy drugs, radiation therapy, colchicine (for gout), digoxin (usually used for heart failure or certain irregular heart rhythms), drugs used to remove or destroy internal parasitic worms, and laxatives. Laxative abuse can lead to weakness, vomiting, diarrhea, electrolyte loss, and other disturbances. Antibiotic use may cause Clostridium difficile–induced diarrhea.
Recognizing that a drug is causing gastroenteritis can be difficult. In mild cases, a doctor can have a person stop taking the drug and later start taking it again. If the symptoms subside when the person stops taking the drug and resume when the person starts taking the drug again, then the drug may be the cause of the gastrointestinal symptoms. In severe cases of gastroenteritis, a doctor may instruct the person to stop taking the drug permanently.
Symptoms
The type and severity of the symptoms depend on the type and quantity of microorganism or toxin ingested. Symptoms also vary according to the person’s resistance. Symptoms often begin suddenly—sometimes dramatically—with a loss of appetite, nausea, or vomiting. Audible rumbling of the intestine and abdominal cramping may occur. Diarrhea is the most common symptom and may be accompanied by visible blood and mucus. Loops of intestine may be painfully swollen (distended) with gas. The person may have a fever, feel generally sick, and experience aching muscles and extreme exhaustion.
Severe vomiting and diarrhea can lead to marked dehydration (see page 970). Symptoms of dehydration include weakness, decreased frequency of urination, dry mouth, and, in infants, lack of tears when crying. Excessive vomiting or diarrhea can result in low levels of potassium in the blood (hypokalemia). Low blood pressure and a rapid heart rate can also develop. Low levels of sodium in the blood (hyponatremia) also may develop, particularly if the person replaces lost fluids by drinking fluids that contain little or no salt, such as water and tea. Water and electrolyte imbalances are potentially serious, especially in the young, the old, and people with chronic diseases. Shock and kidney failure can occur in severe cases.
Diagnosis
The diagnosis of gastroenteritis is usually obvious from the symptoms alone, but the cause often is not. Sometimes other family members or coworkers have recently been ill with similar symptoms. Other times, gastroenteritis can be traced to contaminated water or inadequately cooked, spoiled, or contaminated food, such as raw seafood or mayonnaise left out of the refrigerator too long. Recent travel, especially to certain foreign countries, and recent antibiotic use may give clues as well.
If the symptoms are severe or last for more than 48 hours, stool samples may be cultured and examined in a laboratory for white blood cells and bacteria, viruses, or parasites.
If the symptoms persist beyond a few days, a doctor may need to examine the large intestine with a colonoscope (a flexible viewing tube used to view the lower part of the digestive tract) to determine whether the person has a disease such as ulcerative colitis.
Prevention
A rotavirus vaccine given by mouth is now available that is safe and effective against most strains of rotavirus. This vaccine is now part of the recommended infant vaccination schedule and is given at 2, 4, and 6 months of age (see art on page 1685).
For infants, a simple and effective way to prevent gastroenteritis is breastfeeding. Caregivers should wash their hands thoroughly with soap and water after changing diapers, and diaper-changing areas should be disinfected with a freshly prepared solution of household bleach (1/4 cup bleach diluted in 1 gallon of water). Children with diarrhea should be excluded from day care centers for the duration of their symptoms. Children infected with E. coli that causes bloody diarrhea or Shigella should also have two negative stool cultures before they are allowed to return to the center.
Because most infections that cause gastroenteritis are transmitted by person-to-person contact, particularly through direct or indirect contact with infected stool, good hand washing with soap and water after a bowel movement is the most effective means of prevention. To prevent food-borne infections, hands should be washed before touching food, knives and cutting boards used to cut raw meat should be washed before use with any other food, meat and eggs should be cooked thoroughly, and leftovers should be refrigerated promptly after cooking. Only pasteurized dairy products and pasteurized apple juice should be used. Travelers should try to avoid possibly contaminated food and drink.
Treatment
Usually the only treatment needed for gastroenteritis is getting bed rest and drinking an adequate amount of fluids. Even a person who is vomiting should drink as much as can be tolerated, taking small frequent sips. If vomiting or diarrhea is prolonged or the person becomes severely dehydrated, fluids and electrolytes given by vein (intravenously) may be needed. Because children can become dehydrated more quickly, they should be given fluids with the appropriate mix of salts and sugars. Any of the commercially available solutions designed to replace lost fluids and electrolytes (rehydration solutions) are satisfactory. Carbonated beverages, teas, sports drinks, beverages containing caffeine, and fruit juices are not appropriate. If the child is breastfed, breastfeeding should continue. Drugs that control severe vomiting are not generally given to young children. For adults, a doctor may give a drug, either as an injection or as a suppository, to control severe vomiting.
As the symptoms subside, the person may gradually add foods to the diet. Traditionally, bland foods such as cereal, gelatin, bananas, rice, applesauce, and toast are given, but there is no evidence that these are superior to other foods. If the diarrhea continues for 24 to 48 hours and there is no blood in the stool to indicate a more serious bacterial infection, the doctor may prescribe a drug to control the diarrhea, such as diphenoxylate, or instruct the person to use an over-the-counter drug, such as loperamide. Again, these drugs usually are not given to children under the age of 5.
Because antibiotics can cause diarrhea and may encourage the growth of organisms resistant to antibiotics, they are rarely appropriate, even when a known bacterium is causing gastroenteritis. Antibiotics may be used, however, when certain bacteria, such as Campylobacter, Shigella, and Vibrio, are the cause, and for people who have traveler’s diarrhea.
Parasitic infections are treated with antiparasitic drugs such as metronidazole and nitazoxanide.
Some bacteria are naturally found in the body and promote the growth of good bacteria (probiotics). The use of probiotics, such as lactobacillus (normally found in the mouth, digestive tract, and vagina), is generally safe and may relieve symptoms. They can be given in the form of yogurt with active cultures.
Hemorrhagic Colitis
Hemorrhagic colitis is a type of gastroenteritis in which certain strains of the bacterium Escherichia coli (E. coli) infect the large intestine and produce a toxin (Shiga toxin) that causes bloody diarrhea and other serious complications.
Hemorrhagic colitis can occur in people of all ages but is most common among children and older people. In North America, the most common strain of E. coli that causes hemorrhagic colitis is E. coli O157:H7. These bacteria naturally occur in the intestines of healthy cattle. Outbreaks can be caused by eating undercooked ground beef or by drinking unpasteurized milk or juice and contaminated water. The disease can be transmitted from person to person, particularly among children in diapers.
E. coli toxins damage the lining of the large intestine. If they are absorbed into the bloodstream, they can also affect other organs, such as the kidney.
Symptoms
Severe abdominal cramps begin suddenly along with watery diarrhea, which typically becomes bloody within 24 hours. The diarrhea usually lasts 1 to 8 days. Fever is usually absent or mild but occasionally can exceed 102° F (38.9° C).
About 2 to 7% of people with hemorrhagic colitis develop a severe complication called hemolytic-uremic syndrome (see page 1042). Symptoms include anemia (characterized by fatigue, weakness, and light-headedness) caused by the destruction of red blood cells (hemolytic anemia), a low platelet count (thrombocytopenia), and sudden kidney failure. Some people with hemolytic-uremic syndrome also develop complications of nerve or brain damage, such as seizures or strokes. These complications typically develop in the second week of illness and may be preceded by increasing fever. Hemolytic-uremic syndrome is more likely to occur in children younger than 5 years and in older people. Even without hemolytic-uremic syndrome and its complications, hemorrhagic colitis may cause death in older people.
Diagnosis
A doctor usually suspects hemorrhagic colitis when a person reports bloody diarrhea. To make the diagnosis, a doctor has stool specimens tested for strains of E. coli. Sometimes, the doctor performs a stool test to detect the toxin produced by the E. coli. Other tests, such as colonoscopy, may be performed if a doctor suspects that other diseases may be causing the bloody diarrhea.
Treatment
The most important aspect of treatment is drinking enough fluids. Sometimes so much fluid is lost, however, that a doctor has to replace them intravenously. Antibiotics are not given because they increase the risk of developing hemolytic-uremic syndrome. People who develop complications are likely to require intensive care in the hospital and may need kidney dialysis (see page 265).
Staphylococcal Food Poisoning
Staphylococcal food poisoning results from eating food contaminated with toxins produced by certain types of staphylococci, resulting in diarrhea and vomiting.
The staphylococci bacteria grow in food, in which they produce toxins. Thus, staphylococcal food poisoning does not result from ingesting the bacteria but rather from ingesting the toxins that are already present in the contaminated food. Typical contaminated foods include custard, cream-filled pastry, milk, processed meats, and fish. The risk of an outbreak is high when food handlers with skin infections contaminate foods that are undercooked or left at room temperature.
Symptoms and Diagnosis
Symptoms usually begin abruptly with severe nausea and vomiting starting about 2 to 8 hours after the contaminated food is eaten. Other symptoms may include abdominal cramping, diarrhea, and sometimes headache and fever. Severe fluid and electrolyte loss may cause weakness and very low blood pressure (shock). Symptoms usually last less than 12 hours, and recovery is usually complete. Occasionally, staphylococcal food poisoning is fatal, especially in the very young, the very old, and people weakened by long-term illness.
The symptoms are usually all a doctor needs to diagnose gastroenteritis. A more specific diagnosis of staphylococcal food poisoning may be suspected when other people who ate the same food are similarly affected and when the disorder can be traced to a single source of contamination. To confirm the diagnosis, a laboratory analysis must identify staphylococci in the suspected food, but this analysis is not usually performed.
Prevention and Treatment
Careful food preparation can prevent staphylococcal food poisoning. Anyone who has a skin infection should not prepare food for others until the infection heals. Food should be consumed immediately or refrigerated and not kept at room temperature.
Treatment usually consists of only drinking an adequate amount of fluids. A doctor may give an antinausea drug, either as an injection or as a suppository, to help control severe nausea and vomiting. Sometimes so much fluid is lost that fluids have to be given intravenously.
Clostridium perfringens Food Poisoning
Clostridium perfringens food poisoning results from eating food contaminated by the bacterium Clostridium perfringens. Once in the small intestine, the bacterium releases a toxin that often causes diarrhea.
Some strains cause mild to moderate disease that gets better without treatment, whereas other strains cause severe gastroenteritis that can damage the small intestine and sometimes lead to death. Contaminated meat is usually responsible for outbreaks of Clostridium perfringens food poisoning. Some strains cannot be destroyed by cooking the food thoroughly, whereas others can.
Symptoms
The gastroenteritis starts about 6 to 24 hours after contaminated food is eaten. The most common symptoms are watery diarrhea and abdominal cramps. Although usually mild, the infection also can cause abdominal pain, abdominal expansion (distention) from gas, severe diarrhea, dehydration, and a severe decrease in blood pressure (shock). Symptoms usually last about 24 hours.
Diagnosis and Treatment
A doctor usually suspects the diagnosis when a local outbreak of the disease has occurred. The diagnosis is confirmed by testing contaminated food or the stool of affected people for Clostridium perfringens.
To prevent infection, leftover cooked meat should be refrigerated promptly and reheated thoroughly before serving. The person is given fluids and is encouraged to rest. Antibiotics are not given.
Traveler’s Diarrhea
Traveler’s diarrhea (turista) is characterized by diarrhea, nausea, and vomiting that commonly occur in travelers to areas of the world with poor water purification.
Traveler’s diarrhea can be caused by bacteria, parasites, or viruses.
Organisms that cause the disorder are usually acquired from food or water, especially in developing countries where the water supply may be inadequately treated.
Nausea, vomiting, abdominal cramping, and diarrhea can occur with any degree of severity.
Preventive measures include drinking only bottled carbonated beverages, avoiding uncooked vegetables or fruits, not using ice cubes, and using bottled water to brush teeth.
Treatment involves drinking plenty of fluids and sometimes taking antidiarrheal drugs or antibiotics.
Traveler’s diarrhea occurs when people are exposed to bacteria or, less commonly, parasites to which they have had little exposure and thus no immunity. The bacteria (or parasites) are usually acquired from food or water (including water used to wash foods). Traveler’s diarrhea occurs mostly in developing countries where the water supply is inadequately treated. The organisms most likely to cause traveler’s diarrhea are the types of Escherichia coli (E. coli) that produce certain toxins and some viruses such as norovirus, which has been a particular problem on some cruise ships.
Travelers who avoid drinking local water may still become infected by brushing their teeth with an improperly rinsed toothbrush, drinking bottled drinks with ice made from local water, or eating food that is improperly handled or washed with local water.
Symptoms and Diagnosis
Nausea, vomiting, intestinal rumbling, abdominal cramping, and diarrhea can occur in any combination and with any degree of severity. These symptoms begin 12 to 72 hours after ingesting contaminated food or water. Vomiting, headache, and muscle pain are particularly common in infections caused by norovirus. Most cases are mild and disappear without treatment within 3 to 5 days. Diagnostic tests are rarely needed.
Prevention
Travelers should patronize only those restaurants with a reputation for safety and should not consume any food or beverages from street vendors. Cooked foods that are still hot when served are generally safe. Salads containing uncooked vegetables or fruit and salsa left on the table in open containers should be avoided. Any fruit should be peeled by the traveler. Travelers should drink only bottled carbonated beverages or beverages made with water that has been boiled. Even ice cubes should be made with water that has been boiled. Buffets and fast food restaurants pose an increased risk of infection.
Preventive antibiotics are recommended only for people who are particularly susceptible to the consequences of traveler’s diarrhea, such as those whose immune system is impaired. The antibiotic most commonly recommended is ciprofloxacin.
Treatment
When symptoms occur, treatment includes drinking plenty of fluids and taking drugs to reduce stomach muscle spasms (such as loperamide). These drugs cannot be given to people who have a fever or bloody stools or to children under 2 years of age. In addition, antibiotics (for adults, ciprofloxacin, levofloxacin, azithromycin, or rifaximin; for children, azithromycin) and antidiarrheal drugs (such as loperamide) are usually recommended. Travelers are encouraged to seek medical care if they develop fever or blood in the stool.
Chemical Food Poisoning
Chemical food poisoning results from eating a plant or animal that contains a toxin.
The poisoning occurs after ingesting poisonous species of mushrooms or plants or contaminated fish or shellfish.
The most common symptoms are diarrhea, nausea, and vomiting and sometimes seizures and paralysis.
The diagnosis is based on symptoms and examination of the ingested substance.
Avoiding wild or unfamiliar mushrooms and plants and contaminated fish reduces the risk of poisoning.
Replacing fluids and ridding the stomach of the toxic substance are the best forms of treatment; however, some substances are deadly.
Mushroom (Toadstool) Poisoning
Many species of mushroom are poisonous. The potential for poisoning may vary within the same species, at different times of the growing season, and with cooking. It is difficult to differentiate poisonous from nonpoisonous mushrooms in the wild, even for highly knowledgeable people. Folklore rules are unreliable.
All poisonous mushrooms cause vomiting and abdominal pain. Other symptoms vary greatly depending on mushroom type. Generally, mushrooms that cause symptoms early (within 2 hours) of ingestion are less dangerous than those that cause symptoms later (usually after 6 hours).
Mushrooms that cause early gastrointestinal symptoms (such as Chlorophyllum molybdates, the little brown mushrooms that often grow on lawns) cause vomiting and diarrhea. The diarrhea is occasionally bloody. Some people have headaches or body aches. Symptoms usually go away within 24 hours.
Mushrooms that cause early symptoms that affect the brain and spine include hallucinogenic mushrooms, which contain the hallucinogen psilocybin. The most common are members of the Psilocybe genus, but some other mushrooms also contain psilocybin. Symptoms begin within 15 to 30 minutes of ingestion and include euphoria, enhanced imagination, and hallucinations. A rapid heart beat and high blood pressure often develop, and some children develop a fever. However, these symptoms go away without treatment, and serious consequences are rare, so specific treatment is usually not needed. However, if the person is very agitated, the doctor may prescribe a sedative (such as lorazepam).
In poisoning caused by many species of Inocybe and some species of Clitocybe, the dangerous substance is muscarine. Symptoms, which begin a few minutes to 2 hours after eating, may include increased tearing and salivation, narrowing (constriction) of the pupils, sweating, vomiting, stomach cramps, diarrhea, dizziness, confusion, coma, and, occasionally, seizures. Symptoms are usually mild and go away within 12 hours. Doctors give atropine intravenously to people who have severe symptoms, and nearly all people recover in 24 hours. Without treatment, death can occur in a few hours with severe poisoning.
Mushrooms that cause delayed gastrointestinal symptoms include Amanita phalloides and related types of mushroom (members of the Amanita, Gyromitra, and Cortinarius genera). Amanita phalloides causes 95% of mushroom poisoning deaths. Vomiting and diarrhea start in 6 to 24 hours. Sometimes the blood sugar level drops dangerously low. Symptoms subside for a few days, but then people develop liver failure and sometimes kidney failure. Liver failure causes the skin to turn yellow (jaundice). People with kidney failure may reduce or stop urination. Sometimes the symptoms disappear on their own, but about half of the people who have this type of poisoning die in 5 to 8 days. Those with liver failure may survive if given a liver transplant.
Chinese Restaurant Syndrome
What is popularly called the Chinese restaurant syndrome refers to symptoms such as facial pressure, chest pain, burning sensations throughout the body, and anxiety after eating Chinese food. These symptoms are thought to be a hypersensitivity reaction to monosodium glutamate (MSG), a flavor enhancer often used in Chinese cooking. This reaction is uncommon.
Gyromitra mushrooms also cause delayed vomiting and diarrhea and a low blood sugar level. Other problems include brain toxicity (such as seizures) and, after a few days, liver and kidney failure.
Most Cortinarius mushrooms originate in Europe. Symptoms of gastroenteritis may last for 3 days. Kidney failure, with symptoms of flank pain and decreased urine output, may occur 3 to 20 days after ingestion. Kidney failure often resolves spontaneously.
Plant and Shrub Poisoning
A few commonly grown plants are poisonous. Highly toxic and potentially fatal plants include castor beans, jequirity beans, poison hemlock, and water hemlock, as well as oleander and foxglove, which contain digitalis glycosides. Few plant poisonings can be cured by specific antidotes.
Castor beans contain ricin, an extremely concentrated poison. Ricin has been used in assassination attempts. Castor bean seeds have a very tough shell so the bean must be chewed to release the poison. Jequirity beans can cause death after swallowing. Children can die after chewing only one bean. Poisoning from castor beans or jequirity beans may cause severe vomiting and diarrhea (often bloody) after a delayed period. People later become delirious and have seizures. They may become comatose and die. Doctors sometimes try to flush the beans out of the stomach and intestines before they are absorbed.
Hemlock poisoning can cause symptoms within 15 minutes. People develop a dry mouth and later a rapid heart beat, tremors, sweating, seizures, and
MODERATELY POISONOUS PLANTS
| PLANT | SYMPTOMS | TREATMENT |
| Aloe and related plants | Gastroenteritis (see page 145), kidney inflammation, and skin irritation | Supportive care* if the plant is swallowed and flushing (irrigation) with soap and water if the skin is irritated |
| Azalea | Cholinergic† symptoms | Supportive care* and atropine |
| Cactus and related plants | Infection and formation of abnormal lumps in the skin (granulomas) | Removal of plant spines |
| Caladium and related plants | Irritation of the mouth due to calcium oxalate crystals in the leaves | Supportive care* and use of milk or ice cream to help dissolve the irritant |
| Capsicum and related plants (peppers) | Irritation of the skin and mucous membranes | Supportive care,* irrigation, and possibly use of an agent to help dissolve the irritant |
| Colchicine (autumn crocus, meadow saffron, or glory lily) | Delayed gastroenteritis and malfunction (failure) of many organ systems | Supportive care* |
| Deadly nightshade | Anticholinergic‡ symptoms, a high body temperature, seizures, and hallucinations | Supportive care* For a very high body temperature or seizures, possibly physostigmine |
| Dumbcane (dieffenbachia) | Damage to the mouth due to calcium oxalate crystals in the leaves | Supportive care* and use of milk or ice cream to help dissolve the irritant |
| Fava beans | In people with a deficiency of the enzyme G6PD (which protects red blood cells), gastroenteritis, fever, headache, and hemolytic anemia | Supportive care* For severe anemia and poisoning, gradual removal and replacement of blood with equal volumes of fresh donor blood (exchange transfusion) considered |
| Green potatoes and potato sprouts | Gastroenteritis, hallucinations, and delirium | Supportive care* |
| Holly berries | Gastroenteritis | Supportive care* |
| Jimsonweed | Anticholinergic‡ symptoms, a high body temperature, seizures, and hallucinations | Supportive care* For a very high body temperature or seizures, possibly physostigmine |
| Lily of the valley | Too much potassium in blood and abnormal heart rhythms (arrhythmias) | Supportive care* and antibodies against digitalis |
| Mistletoe | Gastroenteritis | Supportive care* |
| Nettle | Stinging and burning of the skin | Supportive care* |
| Nightshade, common or woody | Gastroenteritis, hallucinations, and delirium | Supportive care* |
| Nightshade, deadly | Anticholinergic‡ symptoms, a high body temperature, seizures, and hallucinations | Supportive care* For a very high body temperature or seizures, possibly physostigmine |
| Philodendron and related plants | Damage to the mouth due to calcium oxalate crystals in the leaves | Supportive care* and use of milk or ice cream to help dissolve the irritant |
| Poinsettia | Mild irritation of the mucous membranes of the mouth, nasal passages, vagina, and urethra | Unnecessary |
| Poison ivy | Inflammation of the skin | See box on page 1286 |
| Pokeweed | Irritation of the mucous membranes of the mouth, nasal passages, vagina, and urethra and gastroenteritis | Supportive care* |
| Pothos | Damage to the mouth due to calcium oxalate crystals in the leaves | Supportive care* and use of milk or ice cream to help dissolve the irritant |
| Yew | Gastroenteritis Rarely, seizures, abnormal heart rhythms, and coma |
Supportive care* |
| *Supportive care may include intravenous administration of fluids, treatments to maintain body functions (such as drugs to lower fever), drugs if blood pressure drops, and a ventilator. | ||
| †Cholinergic symptoms include a slow heart rate, weakened contraction of the heart, difficulty breathing (because airways are constricted), flushing, abdominal cramps, diarrhea, increased urination and salivation, watery eyes, increased sweating, and muscle cramping. | ||
| ‡Anticholinergic symptoms include confusion, blurred vision, constipation, dry mouth, light-headedness, difficulty starting and continuing to urinate, and loss of bladder control. G6PD = glucose-6-phosphate dehydrogenase. |
||
muscle weakness. Water hemlock may cause vomiting and diarrhea, delirium, seizures, and coma.
Oleander, foxglove, and the similar but less toxic lily of the valley can cause vomiting and diarrhea, confusion, irregular heartbeat, and high levels of potassium in the bloodstream. These plants contain a substance very similar to the heart drug digoxin. Doctors sometimes treat people who are poisoned by these plants with a drug used to treat digoxin overdose.
Many other plants cause less serious toxic effects.
Seafood Poisoning
Gastroenteritis may be caused by eating bony fish or shellfish. There are 3 common types of poisoning caused by eating bony fish—ciguatera, tetrodotoxin, and scombroid.
Ciguatera Poisoning: This type of poisoning can occur after eating any of the more than 400 species of fish from the tropical reefs of Florida, the West Indies, or the Pacific. The toxin is produced by certain dinoflagellates, microscopic sea organisms that the fish eat and that accumulate in their flesh. Larger, older fish are more toxic than smaller, younger ones. The flavor of the fish is not affected. Current processing procedures, including cooking, cannot destroy the toxin. The initial symptoms—abdominal cramps, nausea, vomiting, and diarrhea—may begin 2 to 8 hours after the person eats the fish and last 6 to 17 hours. Later symptoms may include itchiness, a pins-and-needles sensation, headache, muscle aches, a reversal of sensations of hot and cold, and facial pain. For months afterward, the sensations may be disabling. Doctors sometimes try to treat affected people with intravenous mannitol (a drug that reduces swelling and pressure), but it is unclear whether this provides any benefit.
Tetrodotoxin Poisoning: Symptoms caused by the toxin in the puffer fish (fugu, a sushi delicacy), which is found most commonly in the seas surrounding Japan, are similar to those caused by fish in ciguatera poisoning. Death may result from paralysis of the muscles that regulate breathing. The toxin cannot be destroyed by cooking or freezing.
Scombroid Poisoning: After fish such as mackerel, tuna, bonito, skipjack, and blue dolphin (mahi mahi) have been caught, the tissues of the fish break down, producing high levels of histamine. When ingested, histamine causes immediate facial flushing. It can also cause nausea, vomiting, stomach pain, and hives (urticaria) a few minutes after the fish is eaten. Symptoms, which are often mistaken for a seafood allergy, usually last less than 24 hours. The fish may taste peppery or bitter.
Unlike other fish poisonings, this poisoning can be prevented by properly storing the fish after it is caught. Antihistamine drugs such as diphenhydramine and ranitidine may help.
Shellfish Poisoning: Shellfish poisoning can occur from June to October, especially on the Pacific and New England coasts. Shellfish such as mussels, clams, oysters, and scallops may ingest certain poisonous dinoflagellates at certain times when the water has a red cast, called the red tide. The dinoflagellates produce a toxin that attacks nerves (such toxins are called neurotoxins. The toxin, saxitoxin, which causes paralytic shellfish poisoning, persists even after the food has been cooked. The first symptom, a pins-and-needles sensation around the mouth, begins 5 to 30 minutes after eating. Nausea, vomiting, and abdominal cramps develop next, followed by muscle weakness. Occasionally, the weakness progresses to paralysis of the arms and legs. Weakness of the muscles needed for breathing may even be severe enough to cause death. Those who survive usually recover completely.
Contaminant Poisoning
Gastroenteritis may affect people who have ingested unwashed fruits and vegetables sprayed with arsenic, lead, or organic insecticides; acidic fluids served in lead-glazed pottery; or food stored in cadmium-lined containers.
Treatment
Most people with chemical food poisoning recover fully and rapidly with nothing more than replacement of fluids and electrolytes. As soon as symptoms begin, a person should try to consume large amounts of fluids. If fluids cannot be tolerated, the person needs to go to an emergency department for intravenous fluids.
If possible, it is often a good idea to rid the stomach of the toxic substance as quickly as possible. For most people, vomiting accomplishes this task. Saving a small amount of the first vomitus may be useful if tests are needed later. If a person cannot vomit adequately and symptoms are severe, a doctor may empty the stomach by placing a small tube through the nose or mouth into the stomach. A laxative helps to pass the toxins from the intestines more quickly.
Specific treatments are sometimes given when the toxin is known.