Acute, Diarrhea and dysentery Definition of Diarrhea? Severity of diarrhea Differential Diagnosis(etiology & mechanism) Pathogenesis of Infectious Diarrhea Toddler's diarrhea Traveler diarrhea Distinguishing Features between Secretory and Osmotic Complications of diarrhea Diagnosis ( history , Physical examination and Laboratory testing) Treatment Foods to Avoid as Part of the "Diarrheal Diet“ Foods to Include as Part of the "Diarrheal Diet Prevention

Acute, Diarrhea and dysentery Acute diarrhea is a major problem when it occurs with malnutrition or in the absence of basic medical care. Bacterial agents tend to cause much more severe illness and typically are seen in outbreaks or in regions with poor public sanitation. Bacterial enteritis should be suspected when there is dysentery (bloody, mucous stools with fever) and whenever severe symptoms are present. These infections can be diagnosed by stool culture or other assays for specific pathogens. Chronic diarrhea lasts more than 2 weeks and has a wide range of possible causes, including more difficult to diagnose serious and benign conditions.

What Is Diarrhea Parents use the word diarrhea to describe loose or watery stools, excessively frequent stools, or stools that are large in volume. Constipation with overflow incontinence can be mislabeled as diarrhea. A more exact definition is excessive daily stool liquid volume (>10 mL stool/kg body weight/day). When assessing a child with diarrhea, the pediatrician should ask about stool texture, volume, and frequency.

Severity of diarrhea: The number of bowel motion can be taken as parameter for severity . Diarrhea can be mild (4-6 motion/day), moderate (6-10 motion/day) or sever (more than 10motion/day). The volume of motion and the character of the stool(formed, soft, loose , very loose, watery or bloody)should also be considered . big volume of watery diarrhea are serious and can easily lead to dehydration.

Pathogenesis of Infectious Diarrhea Enteropathogens can lead to either an inflammatory or noninflammatory response in the intestinal mucosa Enteropathogens elicit noninflammatory diarrhea through; enterotoxin production by some bacteria, destruction of villus (surface) cells by viruses, adherence by parasites, Some viruses, such as rotavirus, target the microvillus tips of the enterocytes. This can result in villus shortening and loss of enterocyte absorptive surface.or by protein NSP4 acts as a viral enterotoxin Inflammatory diarrhea is usually caused by bacteria that directly invade the intestine or produce cytotoxins with consequent fluid, protein, and cells (erythrocytes, leukocytes) that enter the intestinal lumen.

In toxigenic diarrhea enterotoxin produced by Vibrio cholerae, increased mucosal levels of cAMP leads to secretion of H2O, Na+, K+, and HCO3- into the intestinal lumen. In addition, the entry of Na+ and consequently the entry of water into enterocytes are diminished but have no effect on glucose-stimulated Na+ absorption. In secretory cells from crypts, Cl-secretion is minimal in normal subjects and is activated by cyclic adenosine monophosphate (cAMP) in toxigenic and inflammatory diarrhea

ETEC(Enterotoxigenic Escherichia coli) colonizes and adheres to enterocytes of the small bowel via its surface fimbriae (pili) and induces hypersecretion of fluids and electrolytes into the small intestine through 1 of 2 toxins: the heat-labile enterotoxin (LT) or the heat-stable enterotoxin(ST). LT is structurally similar to the V. cholerae toxin, and activates adenylate cyclase, resulting in an increase in intracellular cyclic guanosine monophosphate (cGMP) In inflammatory diarrhea (e.g., Shigella spp. or Salmonella spp.) there is extensive histologic damage, resulting in altered cell morphology and reduced glucose-stimulated Na+ absorption

Differential Diagnosis Diarrhea may be classified by etiology or by physiologic mechanisms (secretory or osmotic). Etiologic agents include viruses, bacteria or their toxins, chemicals, parasites, malabsorbed substances, and inflammation. Secretory diarrhea: occurs when the intestinal mucosa directly secretes fluid and electrolytes into the stool. This secretion may be the result of inflammation as in Crohn's disease or UC, or a chemical stimulus. Cholera is a secretory diarrhea stimulated by the enterotoxin of Vibrio cholerae.

This toxin causes increased levels of cAMP within enterocytes, leading to secretion into the small bowel lumen. Secretion also is stimulated by mediators of inflammation and by various hormones, such as vasoactive intestinal peptide secreted by a neuroendocrine tumor (neuroblastoma).

Osmotic diarrhea occurs after malabsorption of ingested substances malabsorption of the undigested substances creates an osmotic effect which pull water into the bowel lumen. A classic example is lactose intolerance Fermentation of some of these malabsorbed substances often can occur in the colon, resulting in gas production, cramps, and acidic stools. Osmotic diarrhea also can result from maldigestion, such as that seen with pancreatic insufficiency, or with malabsorption caused by intestinal injury.

Certain nonabsorbable laxatives, such as polyethylene glycol and magnesium hydroxide (milk of magnesia) also cause osmotic diarrhea.

Toddler's diarrhea The most common cause of loose stools in early childhood is chronic nonspecific diarrhea, commonly known as toddler's diarrhea. This condition is defined by frequent watery stools in the setting of normal growth and weight gain and is caused by excessive intake of fruit juices that contain non-digestible carbohydrates. Diarrhea typically improves tremendously when the child's beverage intake is reduced or changed.

Distinguishing Features Normal stools are isosmotic that is, they have the same osmolarity as body fluids. Stools are isosmotic because of the relatively free exchange of water across the intestinal mucosa. Osmoles present in the stool are a mixture of electrolytes and other osmotically active solutes. To determine whether the diarrhea is osmotic or secretory, the osmotic gap is calculated: Stool osmotic gap =290-2( Na + k )= 50

The formula for the osmotic gap assumes that the stool is isosmotic (an osmolarity of 290 mOsm/L). Stool sodium and potassium are measured, added together, and multiplied by 2 to account for their associated anions. This result is subtracted from 290. Secretory diarrhea is characterized by an osmotic gap of less than 50 because most of the dissolved substances in the stool are electrolytes. A number significantly higher than 50 defines osmotic diarrhea and indicates that malabsorbed substances other than electrolytes account for fecal osmolarity.

Another way to differentiate between osmotic and secretory diarrhea is to stop all feedings and observe. If the diarrhea stops completely while the patient is receiving nothing by mouth (NPO), the patient has osmotic diarrhea. A child with cholera, a pure secretory diarrhea, would continue to have massive stool output. Neither of these methods for classifying diarrhea works perfectly because most diarrheal illnesses are a mixture of secretory and osmotic components.

Traveler's diarrhea Traveler's diarrhea (TD) is the most common illness affecting travelers. An estimated 10 million people—20% to 50% of international travelers—develop it annually.[TD is defined as three or more unformed stool in 24 hours passed by a traveler, commonly accompanied by abdominal cramps, nausea, and bloating. Its diagnosis does not imply a specific organism, but Enterotoxigenic Escherichia coli is the most commonly isolated pathogen. — Most cases are self-limited; treatment is not routinely prescribed nor the pathogen identified unless symptoms become severe or persistent

History The history should include: the onset of diarrhea, number and character of stools, estimates of stool volume, presence of other symptoms, such as blood in the stool, fever, and weight loss . a list of medications being used should be obtained. Factors that seem to worsen or improve the diarrhea should be determined. Symptoms of dehydration (UOP, thirsty, grade of consciousness)

Physical examination Physical examination should be thorough, with a focus on the abdominal examination. Is there abdominal distention or tenderness? Are bowel sounds hyperactive? Is there blood in the stool on rectal examination? Signs of dehydration

Laboratory testing Laboratory testing should include general stool examination, stool culture and complete blood count if bacterial enteritis is suspected. If diarrhea occurs after a course of antibiotics, a Clostridium difficile toxin assay should be ordered; if stools are reported to be oily or fatty, fecal fat content should be checked. Tests for specific diagnoses should be sent when appropriate, such as serum antibody tests for celiac disease or colonoscopy for suspected UC. A trial of lactose restriction for several days is helpful to rule out lactose intolerance, or a more specific test, such as lactose breath hydrogen analysis, can be performed.

Differential Diagnosis of Diarrhea Infant Child Adolescent Acute Common: Gastroenteritis Gastroenteritis Gastroenteritis Systemic infection Food poisoning Food poisoning Antibiotic associated Systemic infection Antibiotic associated Overfeeding Antibiotic associated Rare  Primary disaccharidase Toxic ingestion Hyperthyroidism deficiency Hirschsprung toxic colitis Adrenogenital syndrome  

Infant Child Adolescent Chronic Common : secondary lactase secondary lactase Irritable bowel syndrome deficiency deficiency Cow's milk/soy protein Inflammatory bowel intolerance  disease Chronic nonspecific diarrhea Irritable bowel syndrome Lactose intolerance  of infancy (toddler's diarrhea) Celiac disease Giardiasis Celiac disease Lactose intolerance Laxative abuse Cystic fibrosis Giardiasis AIDS enteropathy Inflammatory bowel disease AIDS enteropathy AIDS enteropathy  

Infant Child Rare: Primary immune defects Acquired immune defects Familial villous atrophy Secretory tumor Secretory tumors Pseudo-obstruction Congenital chloridorrhea Primary bowel tumor Acrodermatitis enteropathica Lymphangiectasia Abetalipoproteinemia Eosinophilic gastroenteritis Short bowel syndrome Intractable diarrhea syndrome Autoimmune enteropathy

Causes of bloody diarrhea Shigella Escherichia coli Salmonella Campylobacter Yarsinia Entamoeba histolytica Intussusception should be excluded

Complications of diarrhea Dehydration Electrolytes disturbances Acidosis Malnutrition Spared of infection; including vulvovaginitis, urinary tract infection, endocarditis, osteomyelitis, meningitis, pneumonia, hepatitis, peritonitis and septicemia Reactive arthritis; Salmonella, Shigella, Yersinia, Campylobacter, Guillain-Barre syndrome; Campylobacter Glomerulonephritis; Shigella, Campylobacter, Yersinia IgA nephropathy; Campylobacter Erythema nodosum; Yersinia, Campylobacter, Salmonella Hemolytic uremic syndrome; Shigella dysenteriae 1, Escherichia coli O157:H7. Hemolytic anemia; Campylobacter, Yersinia

Treatment Treatment of complication While antibiotics are beneficial in certain type of acute diarrhea they are usually not used except in specific situations. There are concerns that antibiotics may increase the risk of hemolytic uremic syndrome . In poor countries treatment with antibiotics may be beneficial. However, some bacteria are developing antibiotic resistance, particularly Shigella .(What are the indications of antibiotics in acute diarrhea?) The addition of zinc to oral rehydration solution has been proven effective in children with acute diarrhea in developing countries and is recommended by the WHO. However, no evidence suggests efficacy in children living in developed countries, in which the prevalence of zinc deficiency is assumed to be extremely low.

Foods to Avoid as Part of the "Diarrheal Diet" While you are waiting for the diarrhea to end, you should avoid foods that can make it worse, for example: Milk and milk products (except yogurt), such as ice cream or cheese High-fat or greasy foods, such as fried foods Very sweet foods, such as cakes and cookies Foods that have a lot of fibers, such as citrus fruits

Foods to Include As you recover from a bout of diarrheal, the best foods to start eating are easily digested, high-carbohydrate foods. These include: Bananas have high potassium Applesauce or even whole apples are a great source of pectin Plain rice Boiled potatoes Toast Crackers Cooked carrots Baked chicken without the skin or fat. BARTTY is a mnemonic for bananas, applesauce, rice, ,toast, tea and yogurt)

Prevention Many developing countries struggle with huge disease burdens of diarrhea where a wider approach to diarrhea prevention may be required. Promotion of Exclusive Breast-feeding: prevent 13% of all deaths of children <5 yr of age. Improved Complementary Feeding Practices; Complementary foods in developing countries are generally poor in quality and often are heavily contaminated. Vitamin A supplementation reduces all-cause childhood mortality by 21% and diarrhea-specific mortality by 31% Rotavirus Immunization; overall protective efficacy against rotavirus gastroenteritis ranged from 49% to 61%, Improved Water and Sanitary Facilities and Promotion of Personal Hygiene Improved Case Management of Diarrhea