Definition of 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.
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 toxinthat 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. It continues even when there is no oral food intake.
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. 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. In most of these cases, osmotic diarrhea stops when offending agent (e.g. milk, sorbitol) is stopped.
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.
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 avagotomy 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 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.
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.
Cause of Diarrhea
Diarrhea is most commonly due to viral gastroenteritis with rotavirus, which accounts for 40% of cases in children under five. (p. 17) In travelershowever bacterial infections predominate. 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 includeulcerative colitis, Crohn’s disease, microscopic colitis, celiac disease, irritable bowel syndrome and bile acid malabsorption.
There are many causes of infectious diarrhea, which include viruses, bacteria and parasites. Norovirus is the most common cause of viral diarrhea in adults, but rotavirus is the most common cause in children under five years old. Adenovirus types 40 and 41, and astroviruses cause a significant number of infections.
The bacterium Campylobacter is a common cause of bacterial diarrhea, but infections by Salmonellae, Shigellae and some strains of Escherichia coli(E.coli) are frequent.
In the elderly, particularly those who have been treated with antibiotics for unrelated infections, a toxin produced by Clostridium difficile often causes severe diarrhea.
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, andEntamoeba histolytica.
Other infectious agents such as parasites and bacterial toxins also occur.nIn 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.
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.
- enzyme deficiencies or mucosal abnormality, as in food allergy and food intolerance, e.g. 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 inchemotherapy; and
- certain drugs, like orlistat, which inhibits the absorption of fat.
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. 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.
- Diarrhea can be caused by chronic ethanol ingestion.
- 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 only seen on histological examination of colonic biopsies.
- Bile salt malabsorption (primary bile acid diarrhea) where excessive bile acids in the colon produce a secretory diarrhea.
- Hormone-secreting tumors: some hormones (e.g., serotonin) can cause diarrhea if excreted 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.
Signs and Symptoms of Diarrhea
Signs and symptoms associated with diarrhea may include:
- Frequent, loose, watery stools
- Weight loss
- Abdominal cramps
- Abdominal pain
- Blood in the stool
- Nausea and vomiting
When to see a doctor ;
If you’re an adult, see your doctor if:
- Your diarrhea persists beyond three days
- You have symptoms of dehydration – excessive thirst, very dry mouth, very little or no urination
- You have severe abdominal or rectal pain
- You have bloody or black stools
- Your temperature is over 39C (102 F)
Call your doctor if your child’s diarrhea doesn’t improve within 24 hours or if you witness any of the following:
- A child hasn’t had a wet diaper in three or more hours
- A child has a fever of more than 102 F (39 C)
- A child has bloody or black stools
- A child has a dry mouth or cries without tears
- A child is unusually sleepy, drowsy, unresponsive or irritable
- A child has a sunken appearance to the abdomen, eyes or cheeks
- The child’s/baby’s skin does not flatten after being pinched
Risk Factors for Diarrhea
Factors that can increase your chance of getting diarrhea include:
- Having a severely weakened immune system, such as with AIDS or after an organ transplant
- Traveling to a developing country where the water and food supply may be contaminated
- Taking certain medications, apart from antibiotics
- Being so much anxiety
- Consuming too much alcohol
- Consuming too much coffee
Diagnosis of Diarrhea
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 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.
Prevention from Dierrhea
A rotavirus vaccine decrease the rates of diarrhea in a population. 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. In institutions and in communities, interventions that promote hand washing lead to significant reductions in the incidence of diarrhea
Treatment of Diarrhea
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. Diet restrictions such as the BRAT diet are no longer recommended. Research does not support the limiting of milk to children as doing so has no effect on duration of diarrhea. 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. CDC recommends that children and adults with cholera also continue to eat.
Medications such as loperamide (Imodium) and bismuth subsalicylate may be beneficial; however they may be contraindicated in certain situations.
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. 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 (approximately the “taste of tears”). 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. Both agree that drinks with too much sugar or salt can make dehydration worse.
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. 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.
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.
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. Plain water may be used if more specific and effective ORT preparations are unavailable or are not palatable. 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. A nasogastric tube can be used in young children to administer fluids if warranted.
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. A 2005 WHO manual for physicians and other senior health workers is quite emphatic regarding this point: “Food should never be withheld and the child’s usual foods should not be diluted. Breastfeeding should always be continued.” And in the specific example of cholera, CDC also makes the same recommendation.
While antibiotics are beneficial in certain types of acute diarrhea, they are usually not used except in specific situations. There are concerns that antibiotics may increase the risk ofhemolytic uremic syndrome in people infected with Escherichia coli O157:H7. In resource poor countries, treatment with antibiotics may be beneficial. However, some bacteria are developing antibiotic resistance, particularly Shigella. 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. These agents should only be used if bloody diarrhea is not present.
Anti motility agents like loperamide are effective at reducing the duration of diarrhea. 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.
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.
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.
Probiotics reduce the duration of symptoms by one day and reduced the chances of symptoms lasting longer than four days by 60%. The probiotic lactobacillus can help prevent antibiotic associated diarrhea in adults but possibly not children. For those who with lactose intolerance, taking digestive enzymes containing lactase when consuming dairy products is recommended.