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Diarrhea (also spelled diarrhoea) is a condition in which the sufferer has frequent and watery bowel movements. This condition can be a symptom of injury, disease or food poisoning and is usually accompanied by abdominal pain, and often nausea and vomiting. (British spelling is Diarrhoea.)

It is most commonly caused by myriad viral infections but is also often the result of bacterial toxins and sometimes even infection. In sanitary living conditions and with ample food and water available, an otherwise healthy patient typically recovers from the common viral infections in a few days and at most a week. However, for ill or malnourished individuals diarrhea can lead to severe dehydration and can become life-threatening without treatment.

Diarrhea can also be a symptom of more serious diseases, such as dysentery, cholera, or botulism and can also be indicative of a chronic syndrome such as Crohn's disease. It is also an effect of severe radiation sickness.

Symptomatic treatment for diarrhea involves the patient consuming adequate amounts of water to replace that lost, preferably mixed with electrolytes to provide essential salts and some amount of nutrients.

Need to discuss anti-diarrhea drug treatment.

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What is diarrhoea?

NOTE: The comments in this page are written from an Australian perspective but are probably applicable to most Western countries.

Diarrhoea is a very common symptom and is usually understood to mean increase numbers of watery stools. While this is usually the case, it is possible to have watery stools than usual with only normal volume or to have have more frequent small stools with normal volume (hyper defacation, pseudo-diarrhoea, or faecal incontincence). For this reason there is a more formal definition of diarrhoea (in the adult) of stools weighing greater than 200g/day. (In practice we would hardly ever measure faecal weight except as a part of the faecal fat test for malabsorption.)

Since minor diarrhea is very common and rarely of great significance the main medical problem is to decide when it needs investigation or treatment.

Diarrhea that needs medical involvement

  • Diarrhea in infants.
  • Moderate or severe diarrhea in young children.
  • Diarrhea associated with blood.
  • Diarrhea that continues for more than 2 weeks.
  • Diarrhea that is associated with more general illness such as non-cramping abdominal pain[?], fever, weight loss[?], etc.
  • Diarrhea in homosexual males (tends to be more severe and may be associated with AIDS)
  • Diarrhea in travelers (more likely to have exotic infections such as parasites)
  • Diarrhea in food handlers (potential to infect others)
  • Diarrhea in institutions (Hospitals, child care, mental health institutes, geriatric and convalescent homes etc).

Since most people will ignore very minor diarrhea, a patient who actually presents to a doctor is likely to have diarrhoea that is more severe than usual.

Acute Diarrhea

This may defined as diarrhea that lasts less than 2 weeks.

This can nearly always be presumed to be infective although this proven in a minority of cases.

It is often reasonable to reassure a patient, ensure adequate fluid intake and wait and see. In more severe cases or where it is important to find the cause of the illness stool cultures are instituted.

The most common organisms found are Campylobacter (an organism of animal or chicken origin), salmonella (also often of animal origin), Cryptosporidiosis[?] (animal origin), Giardia Lamblia[?] (lives in drinking water). Shigella (dysentery) is less common and usually human in origin. Cholera is rare in Western countries. It is more common in travellers and is usually related to contaminated water (its ultimate source is probably sea water). E Coli[?] is probably a very common cause of diarrhea, especially in travelers, but it can be difficult to detect using current technology. The types of E. coli vary from area to area and country to country.

Viruses, particulary rotavirus is common in children. (Viral diarrhea is probably over-diagnosed by non-doctors). The Norwalk virus is rare.

Toxins and food poisoning can cause diarrhea. These include staphylococcal toxin (see Staphylococcus)(often milk products due to an infected wound in workers), and Bacillus cereus (eg rice in Chinese takeways). Often ?food poisoning? is really salmonella infection.

Diarrhea is a common side effect of drugs (especially antibiotics). Clostridia difficule is a potentially serious infection that is often related to antiobiotic use.

Parasites and worms sometime cause diarrhea but often present with weight loss, irritiablility, rashes or anal itching. The commonest is pinworm (mostly of nuisance value rather than a severe medical illness). Other worms such as hook worm, ascaris and tapeworm are more medically significant and may cause weight loss, anaemia, general unwellness and allergic problems. Amoebic dysentery[?] due to Entaeomeba histolytica[?] is an important cause of bloody diarrhoea in travellers and also sometimes in western countries which requires appropriate and complete medical treatment.

Chronic Diarrhea

Infective diarrhoea

It is not uncommon for diarrhea to persist. Diarrhea due to some organisms may persist for years without significant long term illness. More commonly a diarrhea will slowly ameliorate but the patient becomes a carrier (harbours the infection without illness). This is often an indication for treatment, especially in food workers or institution workers.

Parasites (worms and amoebae) should always be treated. Salmonella is the most common persistent bacterial organism in humans.

Non infective diarrhoea

These tend to be more severe medical illnesses. Malabsorption[?]: This is due to the inability to absorb food, mostly in the small bowel but also due to the pancreas.

Causes include celiac disease (intolerance to gluten, a wheat product), lactose intolerance (Intolerance to milk sugar, common in non-Europeans), Pernicious anaemia (impaired bowel function due to the inability to absorb vitamin B12), loss of pancreatic secretions (may be due to cystic fibrosis or pancreatitis), short bowel syndrome (surgically removed bowel), radiation fibrosis (usually following cancer treatment), other drugs such as chemotherapy.

Chronic inflammatory diseases

There are of unknown origin but a likely to be abnormal immune responses to infection. There is some overlap but the two types are ulcerative colitis and Crohn's disease.

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.

Other important causes

  • Ischaemic bowel disease[?]. This usually affects older people and can be due to blocked arteries.
  • Bowel cancer[?]: Some (but NOT all) bowel cancers may have associated diarrhea. (Cancer of the or large colon is most common)
  • Hormone-secreting tumours: Some hormones can cause diarrhea if excreted to excess (usually from a tumour).

Treatment of diarrhea

  1. Do nothing except ensure adequate fluids. This is the most appropriate treatment in most cases of minor diarrhea.
  2. Anti-diarrhea drugs: Use cautiously as they are said to prolong the illness and may increase the risk of a carrier state. They are useful in some cases, however, when it is important that you don't have diarrhea (e.g. when traveling on a bus).
  3. Antibiotics: Antibiotics may be required if they can be effective and the patient is medically ill. They are sometimes also indicated for workers with carrier states in order to clear up an infection so that the person can resume work. Parasites require appropriate antibiotics.
  4. Intravenous fluids[?] or a "drip": Sometimes, especially in children, dehydration can be life theatening and intravenous fluid may be required.
  5. Dietary manipulation: especially avoid wheat products with celiac disease.
  6. Hygiene and sometime isolation: Hygiene is important in limiting spread of the disease.

See also: Gastroenterology

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