Hepatitis B and C乙型和丙型肝炎

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1、HepatitisBDefinitionØHepatitisBisinflammationofLivercausedbythehepatitisB virus (HBV)ØHBVisanenveloped virus containingapartiallydoublestranded,circularDNA genome,andclassifiedwithinthefamilyhepadnavirusClassification·AcuteHepatitis(95%)ØNewlyacquiredinfectionØ

2、Affectedindividualsnoticesymptomsapproximately1to4monthsafterexposuretothevirusØSymptomsresolveoverweekstomonthsandtheyarecuredoftheinfection·ChronicHepatitis(5%)ØHepatitisBvirustests(HBsAg+)arepositiveafter6monthsØInfectionwithHBVthatlastlongerthan6month.ØOnce

3、infected,nevergoaway.ØMightprogresstodevelopLivercirrhosisandhepatocellularcarcinoma.ØFatalThetransitionfromacutehepatitisBtochronichepatitisBsignifiesafailureoftheimmuneresponsetoeradicatethevirus.IncubationPeriod·Theincubationperiodisusually45-180dayswithanav

4、erageof60-90days.Transmissionroutes·Bloodandbloodproducts·NeedlestickinjuriesoHepatitisBishighlyinfectiousoSharingofneedlesamongIVdrugsabuser·SexualcontactsoAlmostallthebodyfluidsconsiststheproteinoSeminalfluidmaycontainofthevirus·VerticaltransmissionoVerticalt

5、ransmissionfrommaternaltochildduringdeliverythroughthebirthcanalRiskFactor·HighrisksexualbehaviourØUnprotectedsexwithmorethanonepartnerØUnprotectedsexwithsomeonewho'sinfectedwithhbvØSexualcontactwithsamegender·Shareneedlesduringintravenous(IV)druguse·Shareahous

6、eholdwithsomeonewhohasachronicHBVinfection·OccupationexposestohumanbloodØContaminatedbloodproductsØContaminatedsurgicalequipment·Receivehemodialysisforend-stagekidney(renal)disease·TraveltoregionswithhighinfectionratesofHBV,suchasAfrica,CentralandSoutheastAsia,

7、andEasternEuropePathogenesisØHBVenterthenewhost,infectlivercells,hepatocytes.ØThebindingoftheseviralantigenstohepatocytereceptorsinducesviralentrybyreceptor-mediatedendocytosisanduncoatsinthecytoplasmØWithinthecytoplasm,thecoreparticleoftheviriontranslocatesits

8、contentofviralDNAandDNApolymeraseintothehepatocytenucleusØTheDNAisthenorganizedtoformaviralmini-chromosome.ØOncewithinthecellnucleus,thehepatitisBgenomeistranscribedintomRNA