Medical Microbiology

RNAviruses 469

ofhumansandanimalsbyinoculatingnewbornmiceorcellcultureswith

braintissueorsaliva.

Becauseantibodyproductionbeginssolate,serodiagnosisisnotpractic-

able.Serologicalanalysisisusedtocheckforvaccineprotection.Usefultech-

nicaltoolsincludeanEIAorneutralizationtest(RFFIT,rapidfluorescentfocus

inhibitiontestincellcultures).Speciallaboratoriesareusedforthediagnos-

tictesting.

Epidemiology.Lyssavirustype 1 isendemictoNorthAmericaandEuropein

wildanimals(sylvaticrabies)andincertaintropicalareasindomesticpetsas

well,inparticulardogs(urbanrabies).Thereservoirfortheremaininglyssa-

virustypesarebloodsucking(hemovorous)aswellasfructivorousandinsec-

tivorousbats.

Thevirusisexcretedwiththesalivaofthediseasedorterminalincubator

animalandentersotheranimalsorhumansthroughscratchorbitewounds.

Thevirusishighlylabile,sotransmissiononcontaminatedobjectsisvery

rare.Human-to-humantransmissionhasnotbeenconfirmedwiththeexcep-

tionofcasesinwhichrabiesincornealdonorshadgoneunnoticed.

Prevention.Thelongincubationperiodoftherabiesvirus—inhumans

severalweekstoseveralmonths,dependingonthelocalizationandseverity

ofthebitewound—makespostexposureprotectivevaccinationfeasible.De-

velopmentofthevaccineoriginatedwithPasteur,whousedadeadvaccine

fromtheneuraltissuesofinfectedanimals.Useofthisoriginalrabiesvaccine

oftenresultedinseveresideeffectswithallergicencephalomyelitis.Thevac-

cinetypesinusetodayareproducedindiploidhumanembryonalcells

(HDCV=humandiploidcellvaccine),henfibroblastsorduckembryos.No

furtheradversereactionshavebeendescribedwiththesevaccines,sothat

earlierapprehensionsabouttherabiesvaccinearenolongerjustified.

Thepostexposureproceduredependsonthetypeofcontact,thespecies

andconditionofthebitinganimalandtheepidemiologicalsituation(Table

8. 7 ).Exposureisconstitutedbyabite,woundcontaminationwithsalivaor
   lickingofthemucosa,butnotbysimplepetting.Inendemicregions,anyan-
   imalthatbitesunprovokedmustbesuspectedofbeingrabid.
   Postexposureprophylaxisbeginswitharigorouswoundtoilet,themost
   importantpartofwhichisthoroughwashingoutofthewoundwithsoap,
   water,andadisinfectantagent.Passiveimmunizationwith 20 IU/kghuman
   rabiesimmunoglobulin(RIG)isthenbegun,wherebyhalfofthedoseisin-
   stilledaroundthewoundandtheotherhalfisinjectedi.m.Concurrently,
   activeimmunizationisstartedwithsixdosesofHDVCinjectedi.m.on
   days0,3, 7 , 1 4,30,and90.Thecurrenttherapeuticmeasuresaresummarized
   inTable8. 7.
   Important:postexposurevaccinationisapparentlyineffectiveagainstthe
   Africanviralstrains(types 2 – 4).

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Kayser, Medical Microbiology © 2005 Thieme