viral gastroenteritis

VIRAL GASTROENTERITISBy: Dr.Malak M. El-Hazmi (GI T Block , Microbiology : 2011 )

OBJECTIVESDef. of GEViral etiology of GE ( Structures )EpidemiologyClinical Features Lab diagnosisTreatment &Prevention (Vaccine)Rotavirus , Adenovirus , caliciviruses & Astrovirus .

Viruses associated with gastroenteritis

Etiologic agents in severe diarrheal illnesses requiring H of infants & young children Other viruses; Coronaviruses ,Toroviruses , Adenovirus & Enteroviruses

VGE Electron micrographs

Rotavirus AdenoviruscalicivirusAstrovirus

VIRAL GASTROENTERITIS

Epidemiology Distribution ; Worldwide in poor hygiene, overcrowding, and povertyAge ; Infants & young>>Older childrenTransmission ; Faecal-oral routeSeason ; Winter monthsEndemic inf ; Gp A rota & adeno 40,41Epidemic inf ; Norovirus VGE

Clinical Features VGEIP ;ShortSymptoms:D, V, Fever & abdominal crampsDehydration with Na Life threateningWinter vomiting disease: Vomiting > Diarrhoea Calicivirus

VGECell culture: [c/c]Fastidious growing poorly not used Electron microscopy: [EM]Catch all techMany disadvantages not usedSpecific test:ELISA for detection of viral ags in stool [rota , adeno , astro & caliciviruses] Lab diagnosis

VGETreatment:RehydrationPrevention: Sanitation & hygiene measuresNo vaccines except for rotavirus Management

ROTAVIRUSFamily:Reoviridae [Respiratory& Enteric Orphan]Description:11 segments dsRNADouble-layered icosahedralNonenveloped ~ 70 nmRNA dependent RNA polymerase7 groups [A-G]----- GpA most common

EpidemiologyRotaSpread:Faecal-oral routeAge: all age groupsSymptomatic inf ; 6 -24 ms.Peak ; Winter monthsInf ; Endemic

RotaPathogenesis

Clinical featuresRotaIntestinal inf:Infants & young children gastroenteritis or infantile GE IP = 1-2 dsWatery, nonbloody D,V & FDehydrationOutcomes VaryIn developed count. Mortality is lowIn developing count. Mortality is sig. ~1/2 of all GE cases AdmissionDeaths reported

Clinical featuresRotaIntestinal inf:Infants & young children GEOlder children+ adults asymptomaticImmuno ed hostschronic DExtra-intestinal inf:Encephalitis small n.

RotaSample; stool Immunoassay Most usedELISA , ICT& latex agglutinationEMGel electrophoresisRT.PCRCell culture

DiagnosisImmunochromatography Tech.

RotaManagementTreatment:RehydrationPrevention:Sanitation & hygiene measuresVaccine; LAV, oralRotashield ( withdrawn)RotarixRotaTeq*

Rotavirus

Structure EpidemiologyClinical Features Lab diagnosisTreatment Prevention (Vaccine)

ENTERIC ADENOVIRUSESFamily: AdenoviridaeDescription:Nonenveloped, icosahedral , dsDNAOnly V with a fiber protruding from each of the vertices of the capsidFiber Attachment Hemagglutinin Type-specific ag

ENTERIC ADENOVIRUSESClassification:Adenoviruses 6 subgenera[A-F] 51 serotypes Grow in C/CEnteric adenoviruses Subgenus F . 40&41serotypes . Fastidious

ENTERIC ADENOVIRUSESClinical feature:Longer IP Less severe than rotavirusProlonged illnessDiagnosis:Ag detection in stool by ELISA Immunochromatography Tech.

CalicivirusesFamily ; Caliciviridae [Calyx =cup]Description :NonenvelopedssRNA,+ve polarityIcosahedral capsid Two morphologic typesTypical caliciviruses (Sapoviruses)Small Rounded Structured Viruses . (Noroviruses)

EpidemiologyFaecal-oral route [water, shellfish]Outbreaks of GE in schools, camps &cruiseAll age gps Clinical featuresChildren vomiting [projectile]Adults diarrheaDiagnosisViral Ag in stool by ELISA

NOROVIRUS(Norwalk virus)

AstrovirusesFamily; Astroviridae [astro= a star]Description:NonenvelopedssRNA,+ve polarityIcosahedral capsid8 serotypes

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Reference books &the relevant page numbers Medical Microbiology.By: David Greenwood ,Richard Slack,John Peutherer and Mike Barer.17th Edition, 2007. Pages;545-551,565-571

Notes on Medical MicrobiologyBy ; Morag C. Timbury, A. Christine McCartney, Bishan Thakker and Katherine N. Ward (2002) Pages; 338 - 344

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