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Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin with loss of the normal stretchiness of the skin and irritable behaviour. This can progress to decreased urination, loss of skin color, a fast heart rate, and a decrease in responsiveness as it becomes more severe. Loose but non-watery stools in babies who are exclusively breastfed, however, are normal.

The most common cause is an infection of the intestines due to either a virus, bacteria, or parasite—a condition also known as gastroenteritis. These infections are often acquired from food or water that has been contaminated by feces, or directly from another person who is infected. The three types of diarrhea are: short duration watery diarrhea, short duration bloody diarrhea, and persistent diarrhea (lasting more than two weeks, which can be either watery or bloody). The short duration watery diarrhea may be due to cholera, although this is rare in the developed world. If blood is present, it is also known as dysentery. A number of non-infectious causes can result in diarrhea. These include lactose intolerance, irritable bowel syndrome, non-celiac gluten sensitivity, celiac disease, inflammatory bowel disease such as ulcerative colitis, hyperthyroidism, bile acid diarrhea, and a number of medications. In most cases, stool cultures to confirm the exact cause are not required.

Diarrhea can be prevented by improved sanitation, clean drinking water, and hand washing with soap. Breastfeeding for at least six months and vaccination against rotavirus is also recommended. Oral rehydration solution (ORS)—clean water with modest amounts of salts and sugar—is the treatment of choice. Zinc tablets are also recommended. These treatments have been estimated to have saved 50 million children in the past 25 years. When people have diarrhea it is recommended that they continue to eat healthy food and babies continue to be breastfed. If commercial ORS is not available, homemade solutions may be used. In those with severe dehydration, intravenous fluids may be required. Most cases; however, can be managed well with fluids by mouth. Antibiotics, while rarely used, may be recommended in a few cases such as those who have bloody diarrhea and a high fever, those with severe diarrhea following travelling, and those who grow specific bacteria or parasites in their stool. Loperamide may help decrease the number of bowel movements but is not recommended in those with severe disease.

About 1.7 to 5 billion cases of diarrhea occur per year. It is most common in developing countries, where young children get diarrhea on average three times a year. Total deaths from diarrhea are estimated at 1.26 million in 2013—down from 2.58 million in 1990. In 2012, it was the second most common cause of deaths in children younger than five (0.76 million or 11%). Frequent episodes of diarrhea are also a common cause of malnutrition and the most common cause in those younger than five years of age. Other long term problems that can result include stunted growth and poor intellectual development.

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Diarrhea or diarrhoea (from the Greek

, δια dia “through” + ρέω rheo “flow” meaning “flowing through”)<ref>

</ref> is the condition of having three or more loose or liquid bowel movements per day.<ref name=WHO2010>

</ref> The most common cause is gastroenteritis.

Oral rehydration solutions (ORS) with modest amounts of salts and zinc tablets are the treatment of choice and have been estimated to have saved 50 million children in the past 25 years.<ref name=WHO2010a/> In cases where ORS is not available, homemade solutions are often used.

It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and electrolyte disturbances such as potassium deficiency or other salt imbalances. In 2009 diarrhea was estimated to have caused 1.1 million deaths in people aged 5 and over<ref>Straits Times:Diarrhoea kills 3 times more

</ref> and 1.5 million deaths in children under the age of 5.<ref name=WHO2010a>

</ref>

Definition

File:Bristol stool chart.svg

indicate diarrhea]] Diarrhea is defined by the World Health Organization as having three or more loose or liquid stools per day, or as having more stools than is normal for that person.<ref name=WHO2010/>

Acute diarrhea is defined as an abnormally frequent discharge of semisolid or fluid fecal matter from the bowel, lasting less than 14 days, by World Gastroenterology Organisation.<ref name=“WGO”>

</ref>

Secretory

Secretory diarrhea means that there is an increase in the active secretion, or there is an inhibition of absorption. There is little to no structural damage. The most common cause of this type of diarrhea is a cholera toxin that stimulates the secretion of anions, especially chloride ions. Therefore, to maintain a charge balance in the lumen, sodium is carried with it, along with water. In this type of diarrhea intestinal fluid secretion is isotonic with plasma even during fasting.<ref name=“webmd.com”>

</ref> It continues even when there is no oral food intake.

Osmotic

Osmotic diarrhea occurs when too much water is drawn into the bowels. If a person drinks solutions with excessive sugar or excessive salt, these can draw water from the body into the bowel and cause osmotic diarrhea.<ref name=WHOtreatmentdiarrhoea2005>

</ref> Osmotic diarrhea can also be the result of maldigestion (e.g., pancreatic disease or Coeliac disease), in which the nutrients are left in the lumen to pull in water. Or it can be caused by osmotic laxatives (which work to alleviate constipation by drawing water into the bowels). In healthy individuals, too much magnesium or vitamin C or undigested lactose can produce osmotic diarrhea and distention of the bowel. A person who has lactose intolerance can have difficulty absorbing lactose after an extraordinarily high intake of dairy products. In persons who have fructose malabsorption, excess fructose intake can also cause diarrhea. High-fructose foods that also have a high glucose content are more absorbable and less likely to cause diarrhea. Sugar alcohols such as sorbitol (often found in sugar-free foods) are difficult for the body to absorb and, in large amounts, may lead to osmotic diarrhea.<ref name=“webmd.com”/> In most of these cases, osmotic diarrhea stops when offending agent (e.g. milk, sorbitol) is stopped.

Exudative

Exudative diarrhea occurs with the presence of blood and pus in the stool. This occurs with inflammatory bowel diseases, such as Crohn's disease or ulcerative colitis, and other severe infections such as E. coli or other forms of food poisoning.<ref name=“webmd.com”/>

Motility-related diarrhea is caused by the rapid movement of food through the intestines (hypermotility). If the food moves too quickly through the gastrointestinal tract, there is not enough time for sufficient nutrients and water to be absorbed. This can be due to a vagotomy or diabetic neuropathy, or a complication of menstruation

. Hyperthyroidism can produce hypermotility and lead to pseudodiarrhea and occasionally real diarrhea. Diarrhea can be treated with antimotility agents (such as loperamide). Hypermotility can be observed in people who have had portions of their bowel removed, allowing less total time for absorption of nutrients.

Inflammatory

Inflammatory diarrhea occurs when there is damage to the mucosal lining or brush border, which leads to a passive loss of protein-rich fluids and a decreased ability to absorb these lost fluids. Features of all three of the other types of diarrhea

can be found in this type of diarrhea. It can be caused by bacterial infections, viral infections, parasitic infections, or autoimmune problems such as inflammatory bowel diseases. It can also be caused by tuberculosis, colon cancer, and enteritis.

Dysentery

Generally, if there is blood visible in the stools, it is not diarrhea, but dysentery. The blood is trace of an invasion of bowel tissue. Dysentery is a symptom of, among others, Shigella, Entamoeba histolytica, and Salmonella.

Differential diagnosis

File:Stomach colon rectum diagram.svg

.]]

Diarrhea is most commonly due to viral gastroenteritis with rotavirus, which accounts for 40% of cases in children under five.<ref name=WHO2010a/> (p.&nbsp;17) In travelers however bacterial infections predominate.<ref name=“pmid16267716”/> Various toxins such as mushroom poisoning and drugs can also cause acute diarrhea.

Chronic diarrhea can be the part of the presentations of a number of chronic medical conditions affecting the intestine. Common causes include ulcerative colitis, Crohn's disease, microscopic colitis, celiac disease, irritable bowel syndrome and bile acid malabsorption.

Infections

There are many causes of infectious diarrhea, which include viruses, bacteria and parasites.<ref name=“pmid18813221”>

</ref> Norovirus is the most common cause of viral diarrhea in adults,<ref name=“pmid19084472”>

</ref> but rotavirus is the most common cause in children under five years old.<ref name=“pmid19457420”>

</ref> Adenovirus types 40 and 41,<ref name=“pmid1962727”>

</ref> and astroviruses cause a significant number of infections.<ref name=“pmid12442031”>

</ref>

Campylobacter spp. are a common cause of bacterial diarrhea, but infections by Salmonella spp., Shigella spp. and some strains of Escherichia coli are also a frequent cause.<ref name=“pmid19116615”>

</ref>

In the elderly, particularly those who have been treated with antibiotics for unrelated infections, a toxin produced by Clostridium difficile often causes severe diarrhea.<ref name=“pmid19528959”>

</ref>

Parasites do not often cause diarrhea except for the protozoan Giardia, which can cause chronic infections if these are not diagnosed and treated with drugs such as metronidazole,<ref name=“pmid18394362”>

</ref> and Entamoeba histolytica.<ref name=“pmid16973041”>

</ref><ref name=“pmid19370624”>

</ref>

Other infectious agents such as parasites and bacterial toxins also occur.<ref name=“pmid16267716”>

</ref> In sanitary living conditions where there is ample food and a supply of clean water, an otherwise healthy person usually recovers from viral infections in a few days. However, for ill or malnourished individuals, diarrhea can lead to severe dehydration and can become life-threatening.<ref name=“pmid12608880”>

</ref>

Malabsorption

Malabsorption is the inability to absorb food fully, mostly from disorders in the small bowel, but also due to maldigestion from diseases of the pancreas.

Causes include:

Inflammatory bowel disease

The two overlapping types here are of unknown origin:

  • Ulcerative colitis is marked by chronic bloody diarrhea and inflammation mostly affects the distal colon near the rectum.
  • Crohn's disease typically affects fairly well demarcated segments of bowel in the colon and often affects the end of the small bowel.

Irritable bowel syndrome

Another possible cause of diarrhea is irritable bowel syndrome (IBS) which usually presents with abdominal discomfort relieved by defecation and unusual stool (diarrhea or constipation) for at least 3 days a week over the previous 3 months.<ref>

</ref> Symptoms of diarrhea-predominant IBS can be managed through a combination of dietary changes, soluble fiber supplements, and/or medications such as loperamide or codeine. About 30% of patients with diarrhea-predominant IBS have bile acid malabsorption diagnosed with an abnormal SeHCAT test.<ref>

</ref>

Other causes

Pathophysiology

Evolution

According to two researchers, Nesse and Williams, diarrhea may function as an evolved expulsion defense mechanism. As a result, if it is stopped, there might be a delay in recovery.<ref>

</ref> They cite in support of this argument research published in 1973 which found that treating Shigella with the anti-diarrhea drug (Co-phenotrope, Lomotil) caused people to stay feverish twice as long as those not so treated. The researchers indeed themselves observed that: “Lomotil may be contraindicated in shigellosis. Diarrhea may represent a defense mechanism”.<ref>

</ref>

Diagnostic approach

The following types of diarrhea may indicate further investigation is needed:

  • In infants
  • Moderate or severe diarrhea in young children
  • Associated with blood
  • Continues for more than two days
  • Associated non-cramping abdominal pain, fever, weight loss, etc.
  • In food handlers, because of the potential to infect others;
  • In institutions such as hospitals, child care centers, or geriatric and convalescent homes.

A severity score is used to aid diagnosis in children.<ref name=“pmid2371542”>

</ref>

Prevention

A rotavirus vaccine decrease the rates of diarrhea in a population.<ref name=WHO2010a/> New vaccines against rotavirus, Shigella, ETEC, and cholera are under development, as well as other causes of infectious diarrhea.

Probiotics decrease the risk of diarrhea in those taking antibiotics.<ref>

</ref> In institutions and in communities, interventions that promote hand washing lead to significant reductions in the incidence of diarrhea.<ref>

</ref>

Management

In many cases of diarrhea, replacing lost fluid and salts is the only treatment needed. This is usually by mouth – oral rehydration therapy – or, in severe cases, intravenously.<ref name=WHO2010a/> Diet restrictions such as the BRAT diet are no longer recommended.<ref>

</ref> Research does not support the limiting of milk to children as doing so has no effect on duration of diarrhea.<ref>

</ref> To the contrary, WHO recommends that children with diarrhea continue to eat as sufficient nutrients are usually still absorbed to support continued growth and weight gain and that continuing to eat speeds also recovery of normal intestinal functioning.<ref name=WHOtreatmentdiarrhoea2005/> CDC recommends that children and adults with cholera also continue to eat.<ref name = CDCmanualCholera/>

Medications such as loperamide (Imodium) and bismuth subsalicylate may be beneficial; however they may be contraindicated in certain situations.<ref name=“pmid18192963”>

</ref>

Fluids

Oral Rehydration Solution (ORS) can be used to prevent dehydration. Standard home solutions such as salted rice water, salted yogurt drinks, vegetable and chicken soups with salt can be given. Home solutions such as water in which cereal has been cooked, unsalted soup, green coconut water, weak tea (unsweetened), and unsweetened fresh fruit juices can have from half a teaspoon to full teaspoon of salt (from one-and-a-half to three grams) added per liter. Clean plain water can also be one of several fluids given.<ref name=WHOtreatmentdiarrhoea2005/> There are commercial solutions such as Pedialyte, and relief agencies such as UNICEF widely distribute packets of salts and sugar. A WHO publication for physicians recommends a homemade ORS consisting of one liter water with one teaspoon salt (3 grams) and two tablespoons sugar (18 grams) added<ref name=WHOtreatmentdiarrhoea2005/> (approximately the “taste of tears”<ref name=2010WorldCupTravellersGuide>A GUIDE ON SAFE FOOD FOR TRAVELLERS, WELCOME TO SOUTH AFRICA, HOST TO THE 2010 FIFA WORLD CUP (bottom left of page 1).</ref>). Rehydration Project recommends adding the same amount of sugar but only one-half a teaspoon of salt, stating that this more dilute approach is less risky with very little loss of effectiveness.<ref name=RehydrationProject>Rehydration Project, http://rehydrate.org/ Homemade Oral Rehydration Solution Recipe.</ref> Both agree that drinks with too much sugar or salt can make dehydration worse.<ref name=WHOtreatmentdiarrhoea2005/><ref name=RehydrationProject/>

Appropriate amounts of supplemental zinc and potassium should be added if available. But the availability of these should not delay rehydration. As WHO points out, the most important thing is to begin preventing dehydration as early as possible.<ref name=WHOtreatmentdiarrhoea2005/> In another example of prompt ORS hopefully preventing dehydration, CDC recommends for the treatment of cholera continuing to give Oral Rehydration Solution during travel to medical treatment.<ref name = CDCmanualCholera>Community Health Worker Training Materials for Cholera Prevention and Control, CDC, slides at back are dated 11/17/2010. Page 7 states “ . . . Continue to breastfeed your baby if the baby has watery diarrhea, even when traveling to get treatment. Adults and older children should continue to eat frequently.”</ref>

Vomiting often occurs during the first hour or two of treatment with ORS, especially if a child drinks the solution too quickly, but this seldom prevents successful rehydration since most of the fluid is still absorbed. WHO recommends that if a child vomits, to wait five or ten minutes and then start to give the solution again more slowly.<ref name=WHOtreatmentdiarrhoea2005/>

Drinks especially high in simple sugars, such as soft drinks and fruit juices, are not recommended in children under 5 years of age as they may increase dehydration. A too rich solution in the gut draws water from the rest of the body, just as if the person were to drink sea water.<ref name=WHOtreatmentdiarrhoea2005/><ref name=NICE2009>

</ref> Plain water may be used if more specific and effective ORT preparations are unavailable or are not palatable.<ref name=NICE2009/> Additionally, a mix of both plain water and drinks perhaps too rich in sugar and salt can alternatively be given to the same person, which the goal of providing a medium amount of sodium overall.<ref name=WHOtreatmentdiarrhoea2005/> A nasogastric tube can be used in young children to administer fluids if warranted.<ref name=Webb2005>

</ref>

Eating

WHO recommends a child with diarrhea continue to be fed. Continued feeding speeds the recovery of normal intestinal function. In contrast, children whose food is restricted have diarrhea of longer duration and recover intestinal function more slowly. A child should also continue to be breastfed. The WHO states “Food should never be withheld and the child's usual foods should not be diluted. Breastfeeding should always be continued.”<ref name=WHOtreatmentdiarrhoea2005/> And in the specific example of cholera, CDC also makes the same recommendation.<ref name = CDCmanualCholera/> In young children who are not breast-feed and live in the developed world, a lactose free diet may be useful to speed recovery.<ref>

</ref>

Medications

While antibiotics are beneficial in certain types of acute diarrhea, they are usually not used except in specific situations.<ref>

</ref><ref name=CE08/> There are concerns that antibiotics may increase the risk of hemolytic uremic syndrome in people infected with H7.<ref>

</ref> In resource poor countries, treatment with antibiotics may be beneficial.<ref name=CE08>

</ref> However, some bacteria are developing antibiotic resistance, particularly Shigella.<ref>

</ref> Antibiotics can also cause diarrhea, and antibiotic-associated diarrhea is the most common adverse effect of treatment with general antibiotics.

While bismuth compounds (Pepto-Bismol) decreased the number of bowel movements in those with travelers' diarrhea, they do not decrease the length of illness.<ref>

</ref> These agents should only be used if bloody diarrhea is not present.<ref>

</ref>

Anti motility agents like loperamide are effective at reducing the duration of diarrhea.<ref name=CE08/> Codeine is used in the treatment of diarrhea to slow down peristalsis and the passage of fecal material through the bowels – this means that more time is given for water to reabsorb back into the body, which gives a firmer stool, and also means that feces is passed less frequently.<ref name=“codeinephos1”>

</ref>

Bile acid sequestrants such as cholestyramine can be effective in chronic diarrhea due to bile acid malabsorption. Therapeutic trials of these drugs are indicated in chronic diarrhea if bile acid malabsorption cannot be diagnosed with a specific test, such as SeHCAT retention.

Alternative therapies

Zinc supplementation benefits children suffering from diarrhea in developing countries, but only in infants over six months old. This supports the World Health Organisation guidelines for zinc, but not in the very young.<ref>

</ref>

Probiotics reduce the duration of symptoms by one day and reduced the chances of symptoms lasting longer than four days by 60%.<ref>

</ref> The probiotic lactobacillus can help prevent antibiotic associated diarrhea in adults but possibly not children.<ref>

</ref> For those who with lactose intolerance, taking digestive enzymes containing lactase when consuming dairy products is recommended.

Epidemiology

File:Diarrhoeal diseases world map - DALY - WHO2004.svg

for diarrhea per 100,000&nbsp;inhabitants in 2004.<ref>

</ref>

]]

World wide in 2004 approximately 2.5 billion cases of diarrhea occurred which results in 1.5 million deaths among children under the age of five.<ref name=WHO2010a/> Greater than half of these were in Africa and South Asia.<ref name=WHO2010a/> This is down from a death rate of 5 million per year two decades ago.<ref name=WHO2010a/> Diarrhea remains the second leading cause of infant mortality (16%) after pneumonia (17%) in this age group.<ref name=WHO2010a/>

References

diarrhea.txt · Last modified: 2020/03/12 18:33 (external edit)