ACUTE DIARRHEA

By: Ritu Rajan

Diarrhea Definition

Term ‘diarrhea’ (Greek) means ‘to flow through’

Diarrhea is defined as a change in consistency and frequency of stool, i.e. liquid or watery stools, that occur > 3 times a day.

However it is the recent change in consistency & character of stools rather than the number of stools that is more important.

If there is associated blood in the stools, it is termed as dysentery.

ClassificationDiarrhoea is classified as:-On the basis of duration:-Acute ------------------------------------------ if <1weeks,

Persistent ----------------------------------- if 1–2 weeks,

Chronic -------------------------------------- if >2weeks

On the basis of site of pathologySmall Bowel Diarrhea

Large Bowel Diarrhea (Dysentery/ Colitis/ Invasive diarrhea)

What is not a diarrhea ???????

Frequent defecation but with formed stool.Semi-liquid stool at breast feeding.Stool just after feeding (in 1st year infants) Yellow-green liquid stool on 3rd – 6th days

after birth .

Epidemiology of childhood diarrhea Globally it is the 2nd most common cause of child deaths. Diarrhea accounts for 9% of all under five deaths. A loss of more than 0.71 million child live per year. It killed more than 1,600 children under five years of age

every day. Most of these deaths occurs among children less than 2 years. For a children aged under 5 years a median of 3 episodes of

diarrhea occurred per child year.

Cont.…

In India Acute diarrheal disease account for about 8% of death

in under 5 years age group. During the year 2013, about 10.7 million cases with

1,535 deaths were reported in India.

EDIDEMILOGICAL DETERMINANTSETIOLOGYBacterial Viral ParasiticOthers

COMMON CAUSES OF DIARRHEA- BACTERIA Escherichia coli:

(ETEC,EPEC,EIEC, EHEC, EAEC),

Shigella: S.sonnei, S.flexneri, S.boydii & S.dysenteriae,

Vibrio cholera, Salmonella, Campylobacter

species

Areomanas species Bacillus cereus Clostridium difficile

& pefringens, Staphylococcus

aureus, Vibrio

parahemolyticus, Yersinia

enterocolitica, Plesiomonas

shigelloides

COMMON CAUSES OF DIARRHEA- VIRUS

Rotavirus Human caliciviruses: Norovirus spp.;Sapovirus spp. Enteric adenoviruses Astroviruses, Coronaviruses, Cytomegalovirus, Picornavirus

COMMON CAUSES OF DIARRHEA- PARASITE

Giardia lamblia,Cryptosporidium parvum,Entamoeba histolytica,Cyclospora caytanensis,Isospora belli,Balandidium coli,Blastocystis hominis,Encephalitozoon intestinalis ,Trichuris trichiura

COMMON CAUSES OF DIARRHEA-OTHERS

• Metabolic diseaseHyperthyroidismDiabetes mellitusPancreatic insufficiency

• Food allergyLactose intolerance

• Antibiotics• Irritable bowel syndrome

CRYTOSPORIDIUM

ST OR ST/LT ETECSHIGELLA SPP.

ADENOVIRUS

AREOMONAS SPP.

EPEC

NOROVIRUS

V.CHOLERAE

E.HISTOLYTICA

ROTAVIRUS

For age group0-11 months

CRYTOSPORIDIUMST OR ST/LT ETEC

SHIGELLA SPP.

ADENOVIRUS

AREOMONAS SPP.

EPEC

NOROVIRUS

V.CHOLERAE

SAMONALLA

ROTAVIRUS

For age group12-23 months

ROTAVIRUS

CRYTOSPORIDIUM

ST OR ST/LT ETEC

SHIGELLA SPP.

E. HISTOLYTICA

AREOMONAS SPP.

NOROVIRUS

SAPOVIRUS

V.CHOLERAE

SAMONELA

For age group24-59 months

Risk factors Poor sanitation Personal hygiene Non availability of safe drinking water Unsafe food preparation &practices Lack of exclusive or predominant breast feeding Malnutrition (with micronutrient malnutrition vitamin A & zinc deficiency) Measles Hypo- or achlorhydria Selective IAg deficiency HIV

SEASONALITY

Disease Common season

Cholera Winter

Rotavirus diarrhea Winter

Shigellosis Dry summer and rainy season

Modes of transmission Most of the diarrheal agents are transmitted by the faecal-

oral route.•Faecal-oral transmission may be: water- borne;

food –borne: ordirect transmission which implies via fingers, or fomites

or dirt which may be ingested by young children

Physiological disturbance in diarrhea TOTAL BODY WATER (TBW) 65%-75%

ECF (25%) ICF (45%)

CIRCULATING BLOOD

INTESTINAL FLUID

SECRETION

DIARRHEA LOOSE FROM ECFWHICH IS RICH IN SODIUM & LOW POTTASSIUM

LOSS OF WATER FROM BOBY

REDUCTION OR SHRINKAGE OF ECF VOLUME

EXCESSIVE SODIUM LOSS IN STOOLS

RELATIVE DECLINE IN SERUM SODIUM

FALL IN ECF OSMOLALITY

MOVEMET OF WATER FROM ECF TO ICF CAUSES FURTHER SHRINKAGE OF ALREADY REDUCE ECF

COMPARTEMENT

HYPONATREMIC DEHYDRATION

 Mechanisms of DiarrheaPRIMARY MECHANISM DEFECTSecretory Decreased absorption, increased

secretion, electrolyte transportOsmotic Maldigestion, transport defects ingestion

of unabsorbableIncreased motility Decreased transit timeDecreased motility Defect in neuromuscular unit(s) Stasis

(bacterial overgrowth)Decreased surface area (osmotic, motility)

Mucosal invasion

Decreased functional capacity

Decreased Inflammation, decreased colonic reabsorption, increased motility

VIRAL AGENTS CAUSING diarrheaGASTROENTERITISMAJOR VIRUSES OTHER VIRUSES (MINOR):

1. Rotavirus2. Enteric adenoviruses3. Noroviruses : a. Norwalk-like

viruses b. Calicivirus c. Astrovirus

1. Coronaviruses2. Parvoviruses

ROTAVIRUS

Family Reoviridae

Genus Rotavirus

ROTAVIRUS

• 60-80nm in size

• Non-enveloped virus

• Double capsid

• EM appearance of a wheel with radiating spokes

• Icosahedral symmetry• double stranded (ds) RNA in 11 segments

•Genome is composed of 11 segments of double-stranded RNA,

six structural VP1-7

coding for proteins

six nonstructural NSP1-6

PATHOGENESISTRANSMISSION:- Person to person via the faeco-oral routeAfter oral inoculation ---------- infect cells in the villi and enterocytes of small intestine -------- leads to cell death and sloughing of villus ---------- ---resulting in villus blunting ----------causes loss of absorptive function due to the destruction of mature enterocytes --------- causes osmotic diarrhea Also produces secretory diarrheaRotavirus --------- opening of calcium channel ---------- influx of calcium and efflux of sodium and water (NSP4)INTRAENTROCYE CALCIUM ALSO LEAD TO CELL DEATH

WATER FOLLOWS THE MOVEMENT OF ELECTROLYTES AND GLUCOSE

Glucose, Na+, K+, Cl-, Water

Gut lumen

Enterocyte

Villus Tip: Absorption

Crypt: Secretion

NORMAL STATE

NORMAL VILLI BLUNTED VILLI

Destruction of enterocytes:

rotavirus,

Defective absorption

Hypersecretion:

rotavirus,

IMBALANCE BETWEEN ABSORPTION AND SECRETION

ACUTE WATERY DIARRHEA (VIRAL)

Clinical features

Vomiting Diarrhea watery & without blood or visible mucus Fever Dehydration(lethargy and even shock) Transient lactose intolerance --- perianal excoriation

Bacterial AGENTS CAUSING diarrhea

Vibrio cholera (serogroups O1 & O139) Escherichia coli (EHEC,ETEC) Shigella Salmonella Campylobacter

cholera

Vibrio cholereamotile, gram negative, non spore forming

v.choleraeo139

o1Classic

Eltor

pathogenesis

Bacteria -------- reaches to small intestine -------- multiplying in intestinal epithelium -------- produces enterotoxin (CT) -------- attached to GM1(ganglioside receptor) -------- cAMP -------- fluid secretion (rich in k+ & bicarbonates)

CT also inhibit absorption of sodium and chloride Cause massive water and electrolyte loss.

CLINICAL FEATURE: CHOLERA

Rice-watery stool Marked dehydration Projectile vomiting No fever or abdominal pain Muscle cramps Hypovolemic shock Scanty urine

E.coliGram negative, rod shaped, motile by peritrichate flagella.Types of diarrheagenic E.coli:-

Enterotoxigenic E. coli (ETEC)Enteroinvasive E. coli (EIEC)Enteropathogenic E. coli (EPEC)Enterohemorrhagic E. coli (EHEC) (E. coli O157:H7)

Enteroaggregative E. coli (EAggEC)

Pathogenesis

CLINICAL FEATURE: E. COLI DIARRHEA

Watery stoolsVomiting is commonDehydration moderate to severeFever– often of moderate gradeMild abdominal pain

shigella

Gram negative, rod shaped, non motile, non capsulated.Cause bacillary dysentery.The major serotypes of Shigella that cause diarrhea are:

Dysenteriae type 1 or Shigella shigaShigella flexneriShigella sonneiShigella boydii

pathogenesis

Shigella spp.Superficial invasion of colonic mucosa

Which invade through M cell located over peyer patchesAfter phagocytosis

Transmigration of neutrophils in the lumen of colon

Neutrophilic necrosis & degranulation

Further breach of the epithelial barrier

Mucosal destruction

CLINICAL FEATURE:SHIGELLOSISFrequent passage of scanty amount of stools, mostly

mixed with blood and mucusModerate to high grade feverSevere abdominal crampsTenesmus– pain around anus during defecationUsually no dehydration

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