DR.V.PADMAM.D,FRCP(Glasgow).

PROFESSOR OF MEDICINE SREE BALAJI MEDICAL COLLEGE

Epidemiology of DiarrhoeaLeading cause of illness and death among

children in developing countries.estimated 1.3 thousand million episodes and

4 million deaths occur each year in under-fives.

Main cause of death from acute diarrhoea is dehydration. Other important causes of death are dysentery and undernutrition.

DefinitionsAcute Diarrhoea

sudden onset and lasts less than two weeks 90% are infectious in etiology 10% are caused by medications, toxin ingestions,

and ischemia

Chronic Diarrhoea Diarrhoea which lasts for more than 4 weeks Most of the causes are non-infectious

Persistent Diarrhoea -Diarrhoea lasting between 2 to 4 weeks

Classifications of DiarrhoeaDuration- ( Acute, Chronic)Causes- ( infectious, post-infectious, drugs,

endocrine, factitious)Chronic Dirrhoea- Pathophysiologic mechanism (osmotic, secretory, inflammatory,

abnormal motility)

Mechanism of DiarrhoeaOsmotic DiarrhoeaSecretory DiarrhoeaInflammatory DiarrhoeaAbnormal Motility Diarrhoea

Osmotic DiarrhoeaMechanism : -retention of water in the bowel as a result of an

accumulation of non‐absorbable water‐soluble compounds

-cease with fasting, discontinue oral agentsCauses :

-Purgatives like magnesium sulfate or magnesium containing antacids

-especially associated with excessive intake of sorbitol and mannitol.

-Disaccharide intolerance -Generalized malabsorption

Secretory DiarrhoeaMechanism :

Active intestinal secretion of fluid and electrolytes as well as decreased absorption.

Large volume, painless, persist with fastingCauses :

Cholera enterotoxin, heat labile E.coli enterotoxin

Vasoactive Intestinal Peptide hormone in Verner-Morrison syndrome

Bile salts in colon following ileal resectionLaxatives like docusate sodiumCarcinoid tumours

Inflammatory Diarrhoea

Mechanism : -damage to the intestinal mucosal cell leading to

a loss of fluid and blood -pain, fever, bleeding, inflammatory

manifestations

Causes : -- Immunodeficiency patient

Infective conditions like Shigella dysentryInflammatory conditions

Ulcerative colitis and Crohns disease

Abnormal Motility DiarrhoeaMechanism : -Increased frequency of defecation due to

underlying diseases -large volume, signs of malabsorption

(steatorrhoea)Causes :

Diabetes mellitus- autonomic neuropathyPost vagotomyHyperthyroid diarrhoeaIrritable Bowel Syndrome

EtiologyNon- inflammatory :enterotoxin productionVillus destructionAdherence to surfaceInflammatory:Direct invasioncytotoxins

Mucosal adherence- Bacteria adhere to specific

receptors on the mucosa, e.g. adhesions at the tip of the pili or fimbriae

- Mode of action: effacement of intestinal mucosa causing lesions, produce secretory diarrhoea as a result of adherence

- Causing moderate watery diarrhoea

- e.g. enteropathogenic E.coli

Mucosa Invasion- The bacteria penetrate into the intestinal

mucosa, destroying the epithelial cells and causing dysentery

- e.g. Shigella spp. Enteroinvasive E.coli

Campylobacter spp

Toxin Productioni) Enterotoxins- toxin produced by bacteria adhere to the intestinal

epithelium, induce excessive fluid secretion into the bowel lumen, results in watery diarrhoea without physically damaging the mucosa.

- Some enterotoxin preformed in the food can cause vomiting

- e.g Staph.aureus (enterotoxin B)Bacillus cereusVibrio cholerae

ii) Cytotoxins- damage the intestinal mucosa and sometimes vascular

endothelium, leads to bloody diarrhoea with inflammatory cells, decreased absorptive ability.

- e.g. Salmonella spp. Campylobacter spp.Enterohaemorrhagic E.coli 0157

BacterialCampylobacter jejuniSalmonella sp.ShigellaEscherichia coliStaphylococcal enterocolitisBacillus cereusClostridium perfringensClostridium botulinumGastrointestinal tuberculosis

ViralRotavirusNorovirusAdenovirus

Protozoa

• Entamoeba histolytica• Cryptosporidium

• Giardia intestinalis• Schistosomiasis

1. TravelersTourists to Latin America, Africa, and

Asia develop “traveler's diarrhea” commonly due to enterotoxigenic Escherichia coli, Campylobacter, Shigella, and Salmonella.

Visitors to Russia may have increase risk of Giardia-associated diarrhea.

Visitors to Nepal may acquire Cyclospora.

Campers, backpackers, and swimmers in wilderness areas may become infected with Giardia.

Consumers of Certain FoodDiarrhea closely following food

consumption may suggest infection with Salmonella or Campylobacter from

chicken;Enterohemorrhagic Escherichia coli

(O157:H7) from undercooked hamburger Bacillus aureus from fried riceS. aureus from mayonnaise or creamsSalmonella from eggsVibro species, acute hepatitis A or B from

(raw) seafood

Clinical FeaturesDiarrhoea

WateryBloody

Cramping abdominal painNausea, +/- VomitingFeverLoss of appetiteLethargyShock

Extraintestinal manifestationReactive arthritis :Salmonella ,shigella ,

Yersinia, campylobacter C.difficileGuillain-Barre Syndrome: campylobacterGlomerulonephritis:Shigella ,

campylobacter ,YersiniaIgA nephropathy :campylobacterErythema nodosum: Yersinia ,campylobacter,

salmonellaHemolytic anemia : Yersinia ,campylobacterHUS: shigella , E. coli

Bacterial causes of watery diarrhoea and dysentery

Watery diarrhoeaDysentery- Vibrio cholerae - Shigella spp- Enterotoxigenic E.coli (ETEC) - Yersinia

enterocolitica- Enteropathogenic E.coli (EPEC) - Campylobacter spp- Salmonella spp. - Salmonella spp.- Clostridium difficile - Clostridium difficile- Clostridium perfringens - Enteroinvasive E.coli- Campylobacter jejuni - Enterohaemorrhagic- Bacillus cereus E.coli (EHEC)- Staphylococus aureus

+ profuse vomiting

Diurnal variation No relationship to time of day: Infectious

Diarrhea Morning Diarrhea and after meals

Gastric cause Functional bowel disorder (e.g. irritable

bowel) Inflammatory Bowel Disease

Nocturnal Diarrhea (always organic) Diabetic Neuropathy Inflammatory Bowel Disease

Weight Loss Despite normal appetite

Hyperthyroidism Malabsorption

Associated with fever Inflammatory Bowel Disease

Weight loss prior to Diarrhea onset Pancreatic Cancer Tuberculosis Diabetes Mellitus Hyperthyroidism Malabsorption

Acute Diarrhoea Viral,Bacterial, Protozoa (90%) Medications Laxatives or diuretic

abuse Ingestion of

environmental preformed toxin such as seafood

Ischemic Colitis Graft versus Host

Chronic Diarrhoea Irritable Bowel

Syndrome Diverticular disease Colorectal Cancer Bowel Resection Malabsorption Inflammatory Bowel

Disease Celiac Disease Carcinoid tumour

DIFFERENTIAL DIAGNOSISFood intolerance e.g. Lactose intolerance, Inorganic agents like Sodium nitrite, Organic substances like Mushrooms and

shellfish, Drugs e.g. Laxatives and Antibiotics, Emotional stress.

Diagnostic MethodsStool samples : fresh collectedMucous,bld,white cellsOva & parasites:Recent travel to endemic area,-ve stool cultures,diarrhea > 1wkPart of an outbreak ImmunocompromisedStool cultures:As early as possibleSuspected HUSBloody diarrheaoutbreaks

Diagnostic MethodsStool cultures :Routine : Salmonella,

shigella,yersinia,campylobacter.Toxin assays: C. difficle,E.coliSpecial stains:Aeromonas, cryptosporidium & vibrio

sp.Duodenal aspirate & Biopsy: Giardia,

Isospora,cryptosporidium.ELISAE.M.Colonoscopy & sigmoidoscopy.

DRUG INDUCED DIARRHOEAAntibioticsLaxativesAntihypertensivesLactulose AntineoplasticsAntiretroviral drugsMagnesium

containing compounds

Anti arrhythmicsNSAIDsColchicineAntacidsAcid reducing

agentsProstaglandin

analogs

Antibiotic-induced diarrheaunexplained onset of diarrhea that occurs

with the administration of any antibioticdue to disruption of normal intestinal flora,

which leads toeither proliferation of pathogenic

microorganisms or impairment of the metabolic functions of the microflora

Endocrine causesDiabetic autonomic neuropathyThyrotoxicosisNeuroendocrine tumours ~ Zollinger Ellison syndrome ~ VIPoma ~ Somatostatinoma ~ Carcinoid syndrome ~ Medullary carcinoma of thyroid

Hypokalaemia Depletional hyponatraemia Hypernatraemia Hypophosphataemia Hypomagnesemia Dehydration Hypovolaemic shock

Acute Diarrhoea : ManagementAccess Hydration StatusEncourage fluids intake Consider antibiotics if ill or frail Consider referring if very ill, diabetic on insulin

or metformin Children and Elderly are especially prone to

dehydration. A child should be encouraged by their preferred

diet. Breastfeeding should be continued and alternate

with ORS

Oral Rehydration TherapySodium chloride 3.5 gTrisodium citrate dehydrate 2.9 g(or sodium bicarbonate 2.5g)Potassium chloride 1.5gGlucose 20 gTo be dissolved in one litre of clean drinking water

encourage fluid intake e.g. salt + glucose drink to assist in co-transport of sodium into the epithelial cells via the SGLT1 protein, which enhances water and sodium re-absorption in small intestines.