Acute Diarrhoea Definition Increased frequency and water content of stools than is normal for the individual Usually: > 3 stools per day Descriptive Watery, mucoid, dysenteric Pathogenetic: Infective, non-infective

Acute Infective Diarrhoea Epidemiology and predisposition Aetiology Virus (commonest: Rotavirus) Bacteria - Invasive Enterotoxigenic Parasites Fungi

Pathogenesis of Diarrhoea Depends on pathogen VIRUS DIARRHOEA (eg Rotavirus) Effect on villus structure and function Enzyme damage Significant effect on digestion and absorption Secretion-absorption imbalance

Pathogenesis of Bacterial Diarrhoea without mucosal injury mediated by: Enterotoxins Adhesins with mucosal injury mediated by: Adhesins Invasins Cytotoxins

Paediatric Diarrhoea Emerging issues Food borne organisms of increasing importance with contamination of stored/transported food Campylobacter Poultry, meat Salmonella Poultry, Dairy Produce Yersinia Meat Bacillus cereus Reheated cereals Vibrio parahaemolyticus Fish products Unhygienic handling of food Esch coli 0157 mince meat Staph aureus

Mechanisms of acute diarrhoea Osmotic eg Lactose intolerance Secretory eg Cholera Mixed secretory-osmotic eg Rotavirus Mucosal inflammation eg Invasive bacteria Motility disturbance

Effects of Diarrhoea Dehydration Biochemical disturbances Sodium, Potassium Metabolic acidosis Blood glucose Uraemia Convulsions Severe gut damage : ileus, NEC, PLE

Clinical patterns Some associated features depend on pathogen: Rotavirus Invasive bacteria Toxigenic bacteria Fever, abdominal pain, early or late vomiting, other symptoms

Management of diarrhoea Replace the fluids and electrolytes which are lost Drug therapy has very little place Antibiotic Antisecretory Antimotility Nutritional management Follow-up to ensure recovery

Chronic diarrhoea Diarrhoea can be categorized as: Acute: less than days Persistent: More than days Chronic: More than days (Persistent diarrhoea often a prolonged course of acute insult - different management)

Chronic diarrhoea With failure to thrive and excessive stool water losses Small intestinal mucosal injury With failure to thrive but without excessive stool water losses Malabsorption syndromes Without failure to thrive Motility disorder

Small intestinal mucosal injury Initiating acute insult - infection Contributing malnutrition, young age, feeding problem Acute diarrhoea does not stop Leads to malnutrition Aggravation by unmodified food Immunological consequences Contributes big percentage of deaths from diarrhoeal disease

Diarrhoea in symptomatic HIV infection Chronic diarrhoea: AIDS-defining condition Severe mucosal damage with multiple defects of digestion and absorption Associated infections Intestinal super-infection with cryptosporidium, salmonella, opportunists Protein-losing enteropathy can mask hyperglobulinaemia

Lactose intolerance Development of symptoms following lactose exposure due to lactase deficiency Luminal fermentation of undigested lactose Acid diarrhoea with lactose in stools Diagnosed: History, low stool pH, positive reducing sugars Relative lactase deficiency at birth improves with time Needs feed change only with failure to thrive

Lactose intolerance Congenital deficiency very rare Watery, acid diarrhoea from birth Genetic primary adult lactase deficiency very common in Africa Acquired deficiency common in severe gastroenteritis, malnutrition Usually self-limiting without treatment Feed change with persistent high stool water output

Fat malabsorption Diagnosis : stool microscopy, quantitative Pancreatic deficiency (eg cystic fibrosis) Increased appetite cf intestinal disease Greasy floating stools, foul-smelling Treated with enzyme replacement Bile salt deficiency (chronic liver disease) Bile salt deconjugation Bacterial overgrowth in gut disease Treated with “bowel cocktail”

Food allergy Not equivalent to food intolerance Requires exposure and sensitization before symptoms develop GIT and/or skin, nose, resp. symptoms Not common 1 - 4% of children, most < 2yr Careful diagnosis Atopic family history, allergy tests, food elimination and challenge Beware nutritional adequacy of elimination diets

Food intolerance Symptoms after ingestion of food, the word does not indicate the pathology. Can be: Allergic or immunological Allergic enteropathy Biochemical - enzyme deficiencies Lactose intolerance Chemical Laxative, salicylate

Coeliac disease Gluten-induced enteropathy : gliadin fraction of wheat protein Symptoms after exposure to wheat Genetic factors : HLA-B8 Auto-immune disorder Villous atrophy with malabsorption Resultant malnutrition Anti-Endomysium, -gliadin IgA, jejunal biopsies Total wheat product exclusion lifelong

Motility disorders Irritable bowel syndrome, Toddler diarrhoea Between 6 months and 4 years Normal growth and weight gain Intermittent episodes, not at night Stools get progressively more loose through the day, may contain undigested vegetables Family history of “spastic colon” Reassurance most important