2Incidence:-The second most common cause of death in children <5 years.Account for 1.5 million death of children/year globally.(13% of all deaths).Every child <5 years has 3.6 episode of diarrhea/year.Mortality due to diarrhea has declined cause of Rotavirus vaccine, improved nutritional status, better management of disease.
3Etiology:- Feco-oral route transmission. Ingestion of contaminated food or water.Person to person transmission occur in pathogens infectious in small inoculum ,like Shigella,campylobacter,EHEC,Norovirus,Rotavirus, E.histolyticum and Giardia.Most common cause is viral like Rota,norovirus(Norwalk) then adenovirus and enteric viruses.
4Bacterial causes like salmonella,Shigella and E.Coli. Waterborne outbreaks of diarrhea caused by cryptosporidium commonly and others like:-Shigella, E.coli, Norovirus and Giardia.Antibiotics associated pseudomembranous colitis is due to Clostridium defficile.Usually all children acquired Rotavirus, enterovirus and Giardia lamblia in the first 5 years of life.
6Mechanism of Diarrhea:- Non-inflammatory Enterotoxin/AdherenceInflammatoryInvasion/cytotoxinPenetrationLocationProximal Small BowelColonDistal Small BowelIllnessWatery DiarrheaDysenteryEnteric FeverStool ExaminationNo fecal leukocytesMild or no lactoferrinFecal NeutrophillactoferrinFecal mononuclearleukocyteExampleV.cholera,E.coli (ETEC,EPEC,EAEC) ,Norwalk,Giardia,Staphaureus,Cl.perfringes.Shigella,E.coli(EIEC,EHEC) Salmonella enteritidis,Cl.defficile,E.histolytica.Salmonella typhiYersina Enterocolitica
7Osmotic diarrheaDef: Increased amounts of poorly absorped, osmotically active solutes in gut lumenInterferes with reabsorption of waterSolutes are ingestedmagnesiumsorbitolmalabsorption of food (mucosal injury, lactase deficiency)
8Secretory diarrheaExcess secretion of electrolytes, fluid across mucosaUsually coupled with decrease in absorptionWatery, high-volume diarrhea with dehydrationEnterotoxins: Cholera, E. coli, food poisoning, Rotavirus (?), Norwalk virus (?)
9Osmotic/Secretory VOLUME OF STOOL <200ml/24 hrs >200ml/24 hrs Response to fastingDiharrea stopsDiharrea continuesStool Na<70 mEq/l>70 mEqu/lReducing substancesPositiveNegativeStool pH<5>6
13In secretory Diharrea enterotoxin produced by microorganism cause inhibition of Na-Cl pump but not(glucose-Na) pump.In inflammatory diharrea extensive histological damage,release of cytokines leads to increase crypt secretion of Chloride ion by increasing c-AMP.Uncoupling of both Na-H,Hco3-CL –and Na-Glucose uptake.In Shigellosis superficial invasion of colonic mucosa and phagocytic activation with apoptosis and inflammatory interleukins release leading to neutrophilic degranulation.
14Risk Factors:- Environmental contamination of water and food. Young age.Immunedefficiency.Measles.Malnutrition.Lack of exclusive breast feeding.Vitamin A defficiency.Zink defficiency is known also to increase mortality in pneumonea,measles and diharrea.
15Complications:- Dehydration. Prolongation of diharrea with resultant malnutritionSecondary infections.Micronutrient defficiency(Zinc,Iron).Extraintestinal manifestations like reactive arthritis,GuillianBarre(C.jejeuni),glomerulonephritis,HUS and erythema nodosum(salmonella,campylobacter).
16Treatment:-ORS is considered the cornerstone in treatment because it has appropriate osmolality about 310 mos/Kg.ORS can’t be given in shock,ileus,vomiting,high stool output>10cclKGHome made remedies like carbonated beverages(soda),fruit juice are not suitable for rehydration or maintainance because of high osmolality and low Na concentration.
17Enteral feeding should be continued during recovery from episode of diarrhea. Although brush border of intestine is affected ,still satisfactory absorption of CHO,protiens and fats can occur.Once rehydration is complete food should be reintroduced to replace ongoing losses by emesis or diharrea.Breast feeding or non diluted formula should be given.Food like rice soup,vegetables,fruits and yogurt can be given in the recovery period.Fatty food or food high in simple sugars should be avoided.Energy given should be 100 Cal/Kg/d and proteins 2-3glKg/d.Acute lactose intolerance is seen in some patients ,so they should be given Lactose free formula like replacing some of milk requirements with yogurt or milk free diet like comminuted chicken or elemental milk.
20Additional therapy:-Zinc supplement reduce duration ,severity and prevent recurring diharrea.Probiotics like non-pathological bacteria,can restore beneficial intestinal flora,decrease proinflammatory cytokines and increase anti-inflammatory factorsLactobacillus bifidobacterium and lactobacillus rhamenosus reduced duration in Rota.
21Additional therapy:- Anti-motility(Loperamide) NO Role. Anti-emetics like phenothiazine, no role.Ondansetron is a selective anti 5HT receptors and a safe anti-emetic can be given as a single dose before ORS if there is vomiting.Antibiotics should not be given routinely because indiscriminate use lead to bacterial resistance and may prolong bacterial shedding
22Prevention:-Promotion of exclusive breast feeding so no other fluid or food should be given in 1st 6 months.Improved complementary feeding preparation with hygenic practice.Vit-A supplement.Rota virus immunization.oral live attenuated pentavalent vaccine.
23Viral causes of gastroenteritis RotavirusCalcivirus(Norwalk)Enteric AdenovirusAstrovirusOthers Torovirus,Coronavirus and Pesivirus
24Rotavirus Mostly in infants between3-24 months. Low infection inoculum size so person-person spread is common.All children exposed by age 4-5 yearsDouble stranded RNA virusSeveral groups (A-E )Most common cause of viral diarrhea
26PathogenesisSelectively infects &destroys villous tip cells in small intestine ,gastric mucosa is not affected.Villi have absorptive &digestive functions so both are affected in Rota viral infection.Viral enteritis enhance mucosal permeability to macro molecules leading to increase incidence of food allergy.Infants are more prone to infection because of decrease intestinal reserve , gastric acidity and lack of specific immunity.
27Transmission Fecal-oral Contaminated water supplies Poor hygiene Food Fomites
28Clinical manifestations:- Incubation period <48 hrs.Low grade fever,vomiting followed by diharrea lasting<one week,usually watery,no blood or white cells.Infants commonly develop dehydration.Malnourished children develop severe &prolonged illness.Newborns usually are asymptomatic some may develop NEC outbreaks in nurseries.
29Diagnosis of rotavirus Electron microscopySmall intestineStoolAntigen in stoolcommercial ELISAPCR, nucleic acid probesNo RBC or WBC in stool
33Norwalk virus “winter vomiting disease” 1968, Norwalk Cause 40% of nonbacterial epidemicsExplosive epidemicscamps, cruise ships, nursing homesFood borne illnessraw shellfish
34Norwalk virus: Clinical Features 24-48 hour incubation periodvomiting prominentdiarrhea 1-3 daysless severe than rotavirusSmall nm single stranded RNA virusMost common cause of GE outbreaks in older children &adultsSimilar to staph food poisoning
35How does Norwalk virus cause diarrhea? Infection affects proximal small bowelPatchy mucosal injuryMalabsorption? Excess secretion
36Other viruses causing gastroenteritis AdenovirusEnteric serotypes 40,4180-nm single stranded DNADo not cause respiratory symptomsCommon cause of GE in children and adultsProlonged course daysAstrovirusSecond common cause of viral GESingle stranded RNA 30-nm diameterSimilar to Rota infection but milder
38Bacterial Etiology:- Salmonella Two main species with many different serotypes(S.Enterica S.bongori)Serotypes are divided according to somatic O antigen and flagella H antigen.G-ve flagellated rods killed by heat.Transmitted by raw poultry,eggs,vegetables contaminated water.Person-person spread uncommon because of large inoculum size.
39Presentation Salmonellosis(acute enteritis): Incubation period 6-72 hrs.Nausea,vomiting,abdominal pain ,fever diharrhea,usually watery but st bloody.Rarely septicimia and septic shock.Extraintestinal manifestations like osteomyelitis,septic arthritis,meningitisUsually self limiting disease like food poisoning.
40Treatment:- Correct dehydration Antimotility drugs are contraindicated because they increase incidence of perforationAntibiotics are not used in simple enteritis because they increase resistance prolonged bacterial shedding &carrier state.
41Treatment:- Antibiotics are indicated in infants <3 months In patients with immune deficiencyIn patients with typhoid feverIn septicimia and localized infectionIn chronic carrier before cholycystectomy
42Shigella:-There are 4 species (S.dysenteriae S.sonnei S.flexneri S.bodyii)Aerobic non-motile G-ve rodsTransmitted by contaminated water and foodPerson-person is common ,because the inoculum size is only 100 bacteriaInvasion of colonic mucosa with production of enterotoxin
43Complications:-Acute bloody diarrhea( tenesmus,crampy pain with fever)Hemolytic uremic syndrome(acute renal failure,hemolytic anemie,thrombocytopenia)Neurological complications (lethargy,coma and convulsions)Reiter syndrome(conjunctivitis urethritis and arthritis)
44Treatment:- Fluid and electrolyte correction Antibiotics treatment in all children with shigellosis.Antibiotics are given to shorten duration of illness so the child will not be infectiousProlonged course if untreated with resultant malnutritionCeftriaxone is drug of choice
45Pseudomembranous Colitis :- Clostridium difficile is the causative bacteriaIt is found in colon as inactive spore formAntibiotics disrupt normal flora in intestine so dormant spores are activatedThey produce toxin that damage the colonic mucosa with production of membraneAntibiotics implicated mostly Clindamycin,Ampicillin,amxycillinOral metronidazole or Vancomycin is drug of choice
46AmebiasisTwo species that are genetically identical E.histolyticum and E.disparE.dispar usually asymptomatic carrierE.histolytica in 90% of cases are asymptomatic cyst passerInfection transmission is by cyst because they are resistant to cold and chlorinationTrophozoites are not infectiousPerson-person transmission can occur
47SymptomsAmebic dysentery with colicky abdominal pain frequent bowel motions,bloody diarrhea and tenesmusNo general signs and symptomsLow grade feverMay invade intestinal mucosa to cause abscess in liver and rarely in brainChronic amebic colitis indistinguishable from IBD
48TreatmentAll individuals with cyst or trophozoites in their stool whether symptomatic or not should be treatedMetronidazole is the drug of choice for invasive amebiasisIodoquinol and paromomycin is the treatment of choice for amebic cyst
49Giardia lambliaFlagellated protozoan infects the duodenum and proximal jejunumIt is found as cyst and trophozoites formcysts are enough to cause infectionWater and food borne infectionPerson-person infection is commonMost common intestinal parasiteCysts are resistant to chlorination but killed by boiling
50Symptoms Acute infectious diarrhea no mucus or blood in stool Chronic diarrhea leading to malabsorption and failure to thrive with fats and sugar in stoolMost infections are asymptomaticNo extra intestinal spreadDiagnosed by stool analysis or duodenal aspirate and biopsy
51Treatment Asymptomatic carriers are not treated Albendazole treatment for 5 daysOthers like metronidazole,furazolidone and paromomycin are effective treatmentInfections in pts who have agammaglobulinemia should be treated
52Antimicrobial Therapy:- OrganismAntimicrobial AgentIndications for RxCampylobacterErythromycin/QuinolonesEarly in the course of diseaseClostridium difficileMetronidazole/VancomycinModerate to severe diseaseE.coliTMP/SMZSevere or prolonged illnessNursery epidemicsSalmonellaCefotaxime/CeftriaxoneAmpicillin/TMP/SMXBacteremia,suppurationInfants<3mon,typhoid feverShigellaAmpicillin,CeftriaxoneCiprofloxacinAll cases +ve stoolGiardia lambliaMetronidazol/albendazolEntamoeba hisolyticumMetronidazol/iodoquinolTrophozytes/cyst