Gastroenteritis

Gastroenteritis (also known as gastro, gastric flu, tummy bug in some countries, and stomach flu, although unrelated to influenza) is inflammation of the gastrointestinal tract, involving both the stomach and the small intestine (see also gastritis and enteritis) and resulting in acute diarrhea. The inflammation is caused most often by an infection from certain viruses or less often by bacteria, their toxins, parasites, or an adverse reaction to something in the diet or medication. Worldwide, inadequate treatment of gastroenteritis kills 5 to 8 million people per year, and is a leading cause of death among infants and children under 5.

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

Different species of bacteria can cause gastroenteritis, including Salmonella, Shigella, Staphylococcus, Campylobacter jejuni, Clostridium, Escherichia coli, Yersinia, 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.

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.

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.

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

Traveler's diarrhea is usually a type of bacterial gastroenteritis.

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. 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. 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.

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.

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

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

Diagnosis

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.

Prevention

A rotavirus vaccine has between 2000 and 2009 decreased the number of cases of diarrhea due to rotavirus in the United States.

Management

The objective of treatment is to replace lost fluids and electrolytes. Oral rehydration is the preferred treatment of fluid and electrolyte losses caused by diarrhea in children with mild to moderate dehydration.

Rehydration

The primary treatment of gastroenteritis in both children and adults is rehydration, i.e., replenishment of water and electrolytes lost in the stools. Depending on the degree of dehydration, this can be done by giving the person oral rehydration therapy (ORT) or through intravenous delivery. Complex-carbohydrate-based Oral Rehydration Salts (ORS) such as those made from wheat or rice have been found to be superior to simple sugar-based ORS.

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. Plain water may be used if specific ORS are unavailable or not palatable.

Diet

Centers for Disease Control and Prevention (CDC) recommends that breastfed infants continue to be nursed on demand and that formula-fed infants should continue their usual formula immediately upon rehydration with ORS in amounts sufficient to satisfy energy and nutrient requirements and at the usual concentration. Lactose-free or lactose-reduced formulas usually are not necessary.

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, soft drinks (carbonated or flat), juice, gelatin desserts, and other high simple sugar foods should be avoided. The practice of withholding food is not recommended and immediate normal feeding is encouraged.

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.

Pharmacologic therapy

Gastroenteritis is usually an acute and self-limited disease that does not require pharmacologic therapy.

Antibiotics
Antibiotics are usually not useful for gastroenteritis, although they are sometimes used if symptoms are severe or a susceptible bacterial cause is isolated or suspected. If antibiotics are decided on, a fluoroquinolone or macrolide is often used.

Pseudomembranous colitis, usually caused by antibiotics use, is managed by discontinuing the causative agent and treating with either metronidazole or vancomycin.

Antimotility agents
Antimotility drugs have a theoretical risk of causing complications, clinical experience however has shown this to be unlikely. They are thus discouraged in people with bloody diarrhea or diarrhea complicated by a fever.

Loperamide, an opioid analogue, is commonly used for the symptomatic treatment of diarrhea. Loperamide is not recommended in children as it may cross the blood brain barrier due to its immaturity and cause toxicity.

Bismuth subsalicylate (BSS), an insoluble complex of trivalent bismuth and salicylate, can be used in mild-moderate cases.

Antiemetic drugs
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. Metoclopramide also might be helpful.

Alternative medications

Probiotics
Some probiotics have been shown to be beneficial in preventing and treating various forms of gastroenteritis. Fermented milk products (such as yogurt) also reduce the duration of symptoms.

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. A 2009 trial however did not find any benefit from supplementation.

Complications

Dehydration is a common complication of diarrhea. It can be made worse with the withholding fluids or the administration of juice / soft drinks. Malabsorption of lactose, the principal sugar in milk, may occur. It may increase the diarrhea, however, is not a reason to discontinue breastfeeding.

Epidemiology

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.

In 1980 gastroenteritis from all causes caused 4.6 million deaths in children with most of these occurring in the third world. 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.

The incidence in the developed world is as high as 1-2.5 cases per child per year 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.

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. 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.

Translation

The word "Gastroenteritis" occurs as such in the following languages: English, German, Spanish, Indonesian.

Translation(s) in other languages: Bulgarian: Гастроентерит, Czech: Gastroenteritida, French: Gastro-entérite, Italian: Gastroenterite, Dutch: Buikgriep, Japanese: 嘔吐下痢症, Polish: Wirusowe zakażenia przewodu pokarmowego, Portuguese: Gastroenterite, Russian: Гастроэнтерит, Simple English: Stomach flu, Finnish: Gastroenteriitti, Swedish: Mag-tarmkatarr, Chinese: 腸胃炎.