Gastroenteritis

Gastroenteritis (also known as gastric flu, stomach flu, stomach virus, although unrelated to influenza) is inflammation of the gastrointestinal tract, involving both the stomach and the small intestine and resulting in acute diarrhea and vomiting. It can be transferred by contact with contaminated food and water. The inflammation is caused most often^{[citation needed]} by an infection from certain viruses or less often^{[citation needed]} by bacteria, their toxins (e.g. SEB), parasites, or an adverse reaction to something in the diet or medication. Current death rates have come down significantly to approximately 1.5 million deaths annually in the year 2000, largely due to the global introduction of oral rehydration therapy^[1] and is a leading cause of death among infants and children under 5.^[2]

At least 50% of cases of gastroenteritis due to foodborne illness are caused by norovirus.^[3] Another 20% of cases, and the majority of severe cases in children, are due to rotavirus. Other significant viral agents include adenovirus^[4] and astrovirus.

Different species of bacteria can cause gastroenteritis, including Salmonella, Shigella, Staphylococcus, Campylobacter jejuni, Clostridium, Escherichia coli, Yersinia, Vibrio cholerae, and others. Some sources of the infection are improperly prepared food, reheated meat dishes, seafood, dairy, and bakery products. Each organism causes slightly different symptoms but all result in diarrhea. Colitis, inflammation of the large intestine, may also be present.

Risk factors include consumption of improperly prepared foods or contaminated water and travel or residence in areas of poor sanitation. It is also common for river swimmers to become infected during times of rain as a result of contaminated runoff water.^[5]

Contents [hide] 1 Classification 1.1 Bacterial gastroenteritis 1.2 Viral gastroenteritis 2 Symptoms and signs 3 Diagnosis 4 Prevention 5 Management 5.1 Rehydration 5.2 Diet 5.3 Medications 5.4 Alternative medicine 6 Complications 7 Epidemiology 8 History 9 See also 10 References 11 External links

[edit] Classification

Infectious gastroenteritis is caused by a wide variety of bacteria and viruses. It is important to consider infectious gastroenteritis as a diagnosis per exclusionem. A few loose stools and vomiting may be the result of systemic infection such as pneumonia, septicemia, urinary tract infection and even meningitis. Surgical conditions such as appendicitis, intussusception and, rarely, even Hirschsprung's disease may mislead the clinician. Endocrine disorders (e.g. thyrotoxicosis and Addison's disease) are disorders that can cause diarrhea. Also, pancreatic insufficiency, short bowel syndrome, Whipple's disease, coeliac disease, and laxative abuse should be excluded as possibilities.^[6]

[edit] Bacterial gastroenteritis

For a list of bacteria causing gastroenteritis, see above. Pseudomembranous colitis is an important cause of diarrhea in patients often recently treated with antibiotics. Traveler's diarrhea is usually a type of bacterial gastroenteritis.

If gastroenteritis in a child is severe enough to require admission to a hospital, then it is important to distinguish between bacterial and viral infections. Bacteria, Shigella and Campylobacter, for example, and parasites like Giardia can be treated with antibiotics.

[edit] Viral gastroenteritis

Viruses causing gastroenteritis include rotavirus, norovirus, adenovirus and astrovirus. Viruses do not respond to antibiotics and infected children usually make a full recovery after a few days.^[7] Children admitted to hospital with gastroenteritis routinely are tested for rotavirus A to gather surveillance data relevant to the epidemiological effects of rotavirus vaccination programs.^[8][9] These children are routinely tested also for norovirus, which is extraordinarily infectious and requires special isolation procedures to avoid transmission to other patients. Other methods, electron microscopy and polyacrylamide gel electrophoresis, are used in research laboratories.^[10][11]

[edit] Symptoms and signs

Gastroenteritis often involves stomach pain or spasms, diarrhea and/or vomiting, with noninflammatory infection of the upper small bowel, or inflammatory infections of the colon.^{[12][6][13][14]}

The condition is usually of acute onset, normally lasting 1–6 days, and is self-limiting.

• Nausea and vomiting
• Diarrhea
• Loss of appetite
• Fever
• Headaches
• Abnormal flatulence
• Abdominal pain
• Abdominal cramps
• Bloody stools (dysentery - suggesting infection by amoeba, Campylobacter, Salmonella, Shigella or some pathogenic strains of Escherichia coli^[4])
• Fainting and Weakness
• Heartburn

The main contributing factors include poor feeding in infants. Diarrhea is common, and may be followed by vomiting. Viral diarrhea usually causes frequent watery stools, whereas blood stained diarrhea may be indicative of bacterial colitis. In some cases, even when the stomach is empty, bile can be vomited up.

A child with gastroenteritis may be lethargic, suffer lack of sleep, run a low fever, have signs of dehydration (which include dry mucous membranes), tachycardia, reduced skin turgor, skin color discoloration, sunken fontanelles, sunken eyeballs, darkened eye circles, glassy eyes, poor perfusion and ultimately shock.

[edit] Diagnosis

Gastroenteritis is diagnosed based on symptoms, a complete medical history and a physical examination. An accurate medical history may provide valuable information on the existence or inexistence of similar symptoms in other members of the patient's family or friends. The duration, frequency, and description of the patient's bowel movements and if they experience vomiting are also relevant and these question are usually asked by a physician during the examination. ^[15]

No specific diagnostic tests are required in most patients with simple gastroenteritis. If symptoms including fever, bloody stool and diarrhea persist for two weeks or more, examination of stool for Clostridium difficile may be advisable along with cultures for bacteria including Salmonella, Shigella, Campylobacter and enterotoxic Escherichia coli. Microscopy for parasites, ova and cysts may also be helpful.^{[citation needed]}

A complete medical history may be helpful in diagnosing gastroenteritis. A complete and accurate medical history of the patient includes information on travel history, exposure to poisons or other irritants, diet change, food preparation habits or storage and medications. Patients who travel may be exposed to E. Coli infections or parasite infections contacted from beverages or food. Swimming in contaminated water or drinking from suspicious fresh water such as mountain streams or wells may indicate infection from Giardia - an organism found in water that causes diarrhea.

Food poisoning must be considered in cases when the patient was exposed to undercooked or improperly stored food. Depending on the type of bacteria that is causing the condition, the reactions appear in 2 to 72 hours. Detecting the specific infectious agent is required in order to establish a proper diagnosis and an effective treatment plan.

The doctor may want to find whether the patient has been using broad-spectrum or multiple antibiotics in their recent past. If so, they could be the cause of an irritation of the gastrointestinal tract.

During the physical examination, the doctor will look for other possible causes of the infection. Conditions such as appendicitis, gallbladder disease, pancreatitis or diverticulitis may cause similar symptoms but a physical examination will reveal a specific tenderness in the abdomen which is not present in gastroenteritis.

Diagnosing gastroenteritis is mainly an exclusion procedure. Therefore in rare cases when the symptoms are not enough to diagnose gastroenteritis, several tests may be performed in order to rule out other gastrointestinal disorders. These include rectal examinations, complete blood count, electrolytes and kidney function tests. However, when the symptoms are conclusive, no tests apart from the stool tests are required to correctly diagnose gastroenteritis especially if the patient has traveled to at-risk areas.

[edit] Prevention

Percentage of rotavirus tests with positive results, by surveillance week, United States, July 2000--June 2009.

Since 2000, the implementation of a rotavirus vaccine has decreased the number of cases of diarrhea due to rotavirus in the United States.^[16]

Gastroenteritis may be prevented through immunization. ^[17] The U.S. Food and Drug Administration approved in 2006 a rotavirus vaccine called Rotateq that may be given to infants aged 6 to 32 weeks to prevent getting infected with viral gastroenteritis. ^[18] The vaccines may however have side effects that are similar to the mild flu symptoms.

Different types of vaccinations are available for Salmonella typhi and Vibrio cholera and which may be administered to people who intend traveling in at-risk areas. However, the vaccines that are currently available are effective only on rotavirual gastroenteritis.

Doctors recommend that food be properly cooked and stored to prevent gastroenteritis. Avoid suspect food or drink. Thoroughly wash both hands before eating and after using the bathroom or changing diapers. Viral gastroenteritis is a highly contagious disease and thus avoiding crowded spaces such as markets, theaters or shopping centers may also help in preventing infection for those who have weak resistance. Bleaching soiled laundry and household surfaces may help prevent spreading bacteria. ^[19]

[edit] Management

Gastroenteritis is usually an acute and self-limited disease that does not require pharmacological therapy.^[20] The objective of treatment is to replace lost fluids and electrolytes. Oral rehydration is the preferred method of replacing these losses in children with mild to moderate dehydration.^[21] Metoclopramide and ondansetron however may be helpful in children.^[22]

[edit] Rehydration

The primary treatment of gastroenteritis in both children and adults is rehydration, i.e., replenishment of water and electrolytes lost in the stools. This is preferably achieved by giving the person oral rehydration therapy (ORT) although intravenous delivery may be required if a decreased level of consciousness or an ileus is present.^[23][24] Complex-carbohydrate-based oral rehydration therapy such as those made from wheat or rice may be superior to simple sugar-based ORS.^[25]

Sugary drinks such as soft drinks and fruit juice are not recommended for gastroenteritis in children under 5 years of age as they may make the diarrhea worse.^[20] Plain water may be used if specific ORS are unavailable or not palatable.^[20]

[edit] Diet

It is recommended that breastfed infants continue to be nursed on demand and that formula-fed infants should continue their usual formula immediately after rehydration with oral rehydration solutions. Lactose-free or lactose-reduced formulas usually are not necessary.^[26] Children receiving semisolid or solid foods should continue to receive their usual diet during episodes of diarrhea. Foods high in simple sugars should be avoided because the osmotic load might worsen diarrhea; therefore substantial amounts of soft drinks, juice, and other high simple sugar foods should be avoided.^[26] The practice of withholding food is not recommended and immediate normal feeding is encouraged.^[27] The BRAT diet (bananas, rice, applesauce, toast and tea) is no longer recommended, as it contains insufficient nutrients and has no benefit over normal feeding.^[28]

[edit] Medications

Antiemetics

Antiemetic drugs may be helpful for vomiting in children. Ondansetron has some utility with a single dose associated with less need for intravenous fluids, fewer hospitalizations, and decreased vomiting.^[29][30][31] Metoclopramide also might be helpful.^[32] However there was an increased number of children who returned and were subsequently admitted in those treated with ondansetron.^[33] The intravenous preparation of ondansetron may be given orally.^[34]

Antibiotics

Antibiotics are not usually used for gastroenteritis, although they are sometimes used if symptoms are severe (such as dysentery)^[35] or a susceptible bacterial cause is isolated or suspected.^[36] If antibiotics are decided on, a fluoroquinolone or macrolide is often used.^[13] Pseudomembranous colitis, usually caused by antibiotics use, is managed by discontinuing the causative agent and treating with either metronidazole or vancomycin.^[13][14]

Antimotility agents

Antimotility drugs have a theoretical risk of causing complications; clinical experience, however, has shown this to be unlikely.^[6][13] They are thus discouraged in people with bloody diarrhea or diarrhea complicated by a fever.^[12] Loperamide, an opioid analogue, is commonly used for the symptomatic treatment of diarrhea.^[13] Loperamide is not recommended in children as it may cross the immature blood brain barrier and cause toxicity. Bismuth subsalicylate (BSS), an insoluble complex of trivalent bismuth and salicylate, can be used in mild-moderate cases.^[6][13]

Antispasmotics

Butylscopolamine (Buscopan) is useful in treating crampy abdominal pain.^[37]

[edit] Alternative medicine

Probiotics

Some probiotics have been shown to be beneficial in preventing and treating various forms of gastroenteritis.^[28] They reduce both the duration of illness and the frequency of stools.^[38] Fermented milk products (such as yogurt) also reduce the duration of symptoms.^[39]

Zinc

The World Health Organization recommends that infants and children receive a dietary supplement of zinc for up to two weeks after onset of gastroenteritis.^[40] A 2009 trial however did not find any benefit from supplementation.^[41]

[edit] Complications

Dehydration is a common complication of diarrhea. It can be made worse with the withholding fluids or the administration of juice / soft drinks.^[42] Malabsorption of lactose, the principal sugar in milk, may occur. Though it may increase the diarrhea,^[43] however, mothers should continue breastfeeding.

[edit] Epidemiology

Disability-adjusted life year for diarrhea per 100,000 inhabitants.

no data

≤50

50-100

100-200

200-300

300-400

400-500

500-750

750-1000

1000-1250

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≥5000

Every year worldwide rotavirus in children under 5, causes 111 million cases of gastroenteritis and nearly half a million deaths. 82% of these deaths occur in the world's poorest nations.^[44]

In 1980 gastroenteritis from all causes caused 4.6 million deaths in children with most of these occurring in the third world.^[14] Lack of adequate safe water and sewage treatment has contributed to the spread of infectious gastroenteritis. Current death rates have come down significantly to approximately 1.5 million deaths annually in the year 2000, largely due to the global introduction of oral rehydration therapy.^[45]

The incidence in the developed world is as high as 1-2.5 cases per child per year^{[citation needed]} and is a major cause of hospitalization in this age group.

Age, living conditions, hygiene and cultural habits are important factors. Aetiological agents vary depending on the climate. Furthermore, most cases of gastroenteritis are seen during the winter in temperate climates and during summer in the tropics.^[14]

[edit] History

Before the 20th century, the term "gastroenteritis" was not commonly used. What would now be diagnosed as gastroenteritis may have instead been diagnosed more specifically as typhoid fever or "cholera morbus", among others, or less specifically as "griping of the guts", "surfeit", "flux", "colic", "bowel complaint", or any one of a number of other archaic names for acute diarrhea.^[46] Historians, genealogists, and other researchers should keep in mind that gastroenteritis was not considered a discrete diagnosis until fairly recently.

U.S. President Zachary Taylor died of gastroenteritis on July 9, 1850.^[47]