Diarrhea

Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day.^[2] It often lasts for a few days and can result in dehydration due to fluid loss.^[2] Signs of dehydration often begin with loss of the normal stretchiness of the skin and irritable behaviour.^[2] This can progress to decreased urination, loss of skin color, a fast heart rate, and a decrease in responsiveness as it becomes more severe.^[2] Loose but non-watery stools in babies who are exclusively breastfed, however, are normal.^[2]

The most common cause is an infection of the

The word diarrhea is from the Ancient Greek διάρροια from διά dia "through" and ῥέω rheo "flow".

Diarrhea is the spelling in American English, whereas diarrhoea is the spelling in British English.

Slang terms for the condition include "the runs", "the squirts" (or "squits" in Britain^[13]) and "the trots".^[14][15]

The word is often pronounced as /ˌdaɪəˈriːə/ DY-ə-REE-ə.

Definition

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.^[2]

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 Organization.^[16] Acute diarrhea that is watery may be known as AWD (Acute Watery Diarrhoea.)^[17]

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

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.[21] 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.^[19]

Dysentery

If there is blood visible in the stools, it is also known as dysentery. The blood is a trace of an invasion of bowel tissue. Dysentery is a symptom of, among others, Shigella, Entamoeba histolytica, and Salmonella.^[19]

Health effects

Diarrheal disease may have a negative impact on both physical fitness and mental development. "Early childhood malnutrition resulting from any cause reduces physical fitness and work productivity in adults,"

In the latter stages of human digestion, ingested materials are inundated with water and digestive fluids such as gastric acid, bile, and digestive enzymes in order to break them down into their nutrient components, which are then absorbed into the bloodstream via the intestinal tract in the small intestine. Prior to defecation, the large intestine reabsorbs the water and other digestive solvents in the waste product in order to maintain proper hydration and overall equilibrium.^[25] Diarrhea occurs when the large intestine is prevented, for any number of reasons, from sufficiently absorbing the water or other digestive fluids from fecal matter, resulting in a liquid, or "loose", bowel movement.^[26]

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.^[36]

In the elderly, particularly those who have been treated with antibiotics for unrelated infections, a toxin produced by

Parasites, particularly protozoa e.g., Cryptosporidium spp., Giardia spp., Entamoeba histolytica, Blastocystis spp., Cyclospora cayetanensis, are frequently the cause of diarrhea that involves chronic infection. The broad-spectrum antiparasitic agent nitazoxanide has shown efficacy against many diarrhea-causing parasites.^[38]

Other infectious agents, such as

Open defecation is a leading cause of infectious diarrhea leading to death.^[40]

Poverty is a good indicator of the rate of infectious diarrhea in a population. This association does not stem from poverty itself, but rather from the conditions under which impoverished people live. The absence of certain resources compromises the ability of the poor to defend themselves against infectious diarrhea. "Poverty is associated with poor housing, crowding, dirt floors, lack of access to clean water or to sanitary disposal of fecal waste (sanitation), cohabitation with domestic animals that may carry human pathogens, and a lack of refrigerated storage for food, all of which increase the frequency of diarrhea ... Poverty also restricts the ability to provide age-appropriate, nutritionally balanced diets or to modify diets when diarrhea develops so as to mitigate and repair nutrient losses. The impact is exacerbated by the lack of adequate, available, and affordable medical care."^[41]

One of the most common causes of infectious diarrhea is a lack of clean water. Often, improper fecal disposal leads to contamination of groundwater. This can lead to widespread infection among a population, especially in the absence of water filtration or purification. Human feces contains a variety of potentially harmful human

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:^{[citation needed]}

• enzyme deficiencies or mucosal abnormality, as in
  celiac disease (gluten intolerance), lactose intolerance (intolerance to milk sugar, common in non-Europeans), and fructose malabsorption
  .
• pernicious anemia, or impaired bowel function due to the inability to absorb vitamin B₁₂,
• loss of pancreatic secretions, which may be due to cystic fibrosis or pancreatitis,
• structural defects, like short bowel syndrome (surgically removed bowel) and radiation fibrosis, such as usually follows cancer treatment and other drugs, including agents used in chemotherapy; and
• certain drugs, like orlistat, which inhibits the absorption of fat.

Inflammatory bowel disease

The two overlapping types here are of unknown origin:

• 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 three days a week over the previous three months.^[49] Symptoms of diarrhea-predominant IBS can be managed through a combination of dietary changes, soluble fiber supplements and medications such as loperamide or codeine. About 30% of patients with diarrhea-predominant IBS have bile acid malabsorption diagnosed with an abnormal SeHCAT test.^[50]

Other diseases

Diarrhea can be caused by other diseases and conditions, namely:

• Chronic ethanol ingestion^[51]
• Hyperthyroidism^[52]
• Certain medications^[52]
• Bile acid malabsorption^[52]
• Ischemic bowel disease: This usually affects older people and can be due to blocked arteries.
• Microscopic colitis, a type of inflammatory bowel disease where changes are seen only on histological examination of colonic biopsies.
• colon
  produce a secretory diarrhea.
• Hormone-secreting tumors: some hormones, e.g. serotonin, can cause diarrhea if secreted in excess (usually from a tumor).
• Chronic mild diarrhea in infants and toddlers may occur with no obvious cause and with no other ill effects; this condition is called
  toddler's diarrhea
  .
• Environmental enteropathy
• Radiation enteropathy following treatment for pelvic and abdominal cancers.

Medications

Over 700 medications, such as penicillin, are known to cause diarrhea.^[53][54] The classes of medications that are known to cause diarrhea are laxatives, antacids, heartburn medications, antibiotics, anti-neoplastic drugs, anti-inflammatories as well as many dietary supplements.^[19]

Pathophysiology

Evolution

According to two researchers,

• 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
  travelers
• 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.^[58]

When diarrhea lasts for more than four weeks a number of further tests may be recommended including:^[59]

• Complete blood count and a ferritin if anemia is present
• Thyroid stimulating hormone
• celiac disease
• Fecal calprotectin to exclude inflammatory bowel disease
• Clostridioides difficile
• A colonoscopy or fecal immunochemical testing for cancer, including biopsies to detect microscopic colitis
• Testing for
  bile acids
  depending on availability
• Hydrogen breath test looking for lactose intolerance
• Further tests if
  pelvic radiation disease or small intestinal bacterial overgrowth
  suspected.

A 2019 guideline recommended that testing for ova and parasites was only needed in people who are at high risk though they recommend routine testing for giardia.^[60] Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were not recommended.^[60]

Epidemiology

Worldwide in 2004, approximately 2.5 billion cases of diarrhea occurred, which resulted in 1.5 million deaths among children under the age of five.^[1] Greater than half of these were in Africa and South Asia.^[1] This is down from a death rate of 4.5 million in 1980 for gastroenteritis.^[62] Diarrhea remains the second leading cause of infant mortality (16%) after pneumonia (17%) in this age group.^[1]

The majority of such cases occur in the developing world, with over half of the recorded cases of childhood diarrhea occurring in Africa and Asia, with 696 million and 1.2 billion cases, respectively, compared to only 480 million in the rest of the world.^[63]

Infectious diarrhea resulted in about 0.7 million deaths in children under five years old in 2011 and 250 million lost school days.^[64][65] In the Americas, diarrheal disease accounts for a total of 10% of deaths among children aged 1–59 months while in South East Asia, it accounts for 31.3% of deaths.^[66] It is estimated that around 21% of child mortalities in developing countries are due to diarrheal disease.^[67]

Prevention

Sanitation

Numerous studies have shown that improvements in drinking water and sanitation (WASH) lead to decreased risks of diarrhoea.^[68] Such improvements might include for example use of water filters, provision of high-quality piped water and sewer connections.^[68]

In institutions, communities, and households, interventions that promote hand washing with soap lead to significant reductions in the incidence of diarrhea.^[69] The same applies to preventing open defecation at a community-wide level and providing access to improved sanitation.^[64][70] This includes use of toilets and implementation of the entire sanitation chain connected to the toilets (collection, transport, disposal or reuse of human excreta).

There is limited evidence that safe disposal of child or adult feces can prevent diarrheal disease.^[71][72]

Hand washing

Basic sanitation techniques can have a profound effect on the transmission of diarrheal disease. The implementation of hand washing using soap and water, for example, has been experimentally shown to reduce the incidence of disease by approximately 30–48%.^[73][74][69] Hand washing in developing countries, however, is compromised by poverty as acknowledged by the CDC: "Handwashing is integral to disease prevention in all parts of the world; however, access to soap and water is limited in a number of less developed countries. This lack of access is one of many challenges to proper hygiene in less developed countries." Solutions to this barrier require the implementation of educational programs that encourage sanitary behaviours.^[75]

Water

Given that water contamination is a major means of transmitting diarrheal disease, efforts to provide clean water supply and improved sanitation have the potential to dramatically cut the rate of disease incidence. In fact, it has been proposed that we might expect an 88% reduction in child mortality resulting from diarrheal disease as a result of improved water sanitation and hygiene.^[42][76] Similarly, a meta-analysis of numerous studies on improving water supply and sanitation shows a 22–27% reduction in disease incidence, and a 21–30% reduction in mortality rate associated with diarrheal disease.^[77]

Chlorine treatment of water, for example, has been shown to reduce both the risk of diarrheal disease, and of contamination of stored water with diarrheal pathogens.^[78]

Vaccination

Immunization against the pathogens that cause diarrheal disease is a viable prevention strategy, however it does require targeting certain pathogens for vaccination. In the case of Rotavirus, which was responsible for around 6% of diarrheal episodes and 20% of diarrheal disease deaths in the children of developing countries, use of a Rotavirus vaccine in trials in 1985 yielded a slight (2–3%) decrease in total diarrheal disease incidence, while reducing overall mortality by 6–10%. Similarly, a Cholera vaccine showed a strong reduction in morbidity and mortality, though the overall impact of vaccination was minimal as Cholera is not one of the major causative pathogens of diarrheal disease.^[79] Since this time, more effective vaccines have been developed that have the potential to save many thousands of lives in developing nations, while reducing the overall cost of treatment, and the costs to society.^[80][81]

Rotavirus vaccine decreases the rates of diarrhea in a population.^[1][82] New vaccines against rotavirus, Shigella, Enterotoxigenic Escherichia coli (ETEC), and cholera are under development, as well as other causes of infectious diarrhea.^{[medical citation needed]}

Nutrition

Dietary deficiencies in developing countries can be combated by promoting better eating practices. Zinc supplementation proved successful showing a significant decrease in the incidence of diarrheal disease compared to a control group.^[83][84] The majority of the literature suggests that vitamin A supplementation is advantageous in reducing disease incidence.^[85] Development of a supplementation strategy should take into consideration the fact that vitamin A supplementation was less effective in reducing diarrhea incidence when compared to vitamin A and zinc supplementation, and that the latter strategy was estimated to be significantly more cost effective.^[86]

Breastfeeding

Breastfeeding practices have been shown to have a dramatic effect on the incidence of diarrheal disease in poor populations. Studies across a number of developing nations have shown that those who receive exclusive breastfeeding during their first 6 months of life are better protected against infection with diarrheal diseases.^[87] One study in Brazil found that non-breastfed infants were 14 times more likely to die from diarrhea than exclusively breastfed infants.^[88] Exclusive breastfeeding is currently recommended for the first six months of an infant's life by the WHO,^[89][90] with continued breastfeeding until at least two years of age.^[90]

Others

Oral rehydration solution (ORS) (a slightly sweetened and salty water) 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.^[20] 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^[20] (approximately the "taste of tears"^[98]). 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.^[99] Both agree that drinks with too much sugar or salt can make dehydration worse.^[20][99]

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.^[20] 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.^[95]

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.^[20]

Drinks especially high in simple sugars, such as

The 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. The WHO states "Food should never be withheld and the child's usual foods should not be diluted. Breastfeeding should always be continued."[20] In the specific example of cholera, the CDC makes the same recommendation.^[95] Breast-fed infants with diarrhea often choose to breastfeed more, and should be encouraged to do so.^[20] In young children who are not breast-fed and live in the developed world, a lactose-free diet may be useful to speed recovery.^[102] Eating food containing fibers may help.^[103]

Medications

Antidiarrheal agents can be classified into four different groups: antimotility, antisecretory, adsorbent, and anti-infectious.

Diosmectite, a natural aluminomagnesium silicate clay, is effective in alleviating symptoms of acute diarrhea in children,^[111] and also has some effects in chronic functional diarrhea, radiation-induced diarrhea, and chemotherapy-induced diarrhea.^[52] Another absorbent agent used for the treatment of mild diarrhea is kaopectate.

Racecadotril an antisecretory medication may be used to treat diarrhea in children and adults.^[104] It has better tolerability than loperamide, as it causes less constipation and flatulence.^[112] However, it has little benefit in improving acute diarrhea in children.^[113]

Zinc supplementation may benefit children over six months old with diarrhea in areas with high rates of malnourishment or zinc deficiency.[115] This supports the World Health Organization guidelines for zinc, but not in the very young.

A Cochrane Review from 2020 concludes that probiotics make little or no difference to people who have diarrhea lasting 2 days or longer and that there is no proof that they reduce its duration.^[116] The probiotic lactobacillus can help prevent antibiotic-associated diarrhea in adults but possibly not children.^[117] For those with lactose intolerance, taking digestive enzymes containing lactase when consuming dairy products often improves symptoms.

See also

• Dysentery – Inflammation of the intestine causing diarrhea with blood
• Fernando Mazariegos – Guatemalan scientist (1938–2018)

References

External links

Wikipedia's health care articles can be viewed offline with the Medical Wikipedia app.

• WHO fact sheet on diarrhoeal disease