Medical Microbiology

RNAviruses 467

&RSvirusescausebronchiolitisorpneumonia,mainlyinchildrenuptosix

monthsofage,orrarelyuptotwoyears.Immunestatusappearstoplayan

importantroleinthecourseoftheinfection.Ithasbeendeterminedthatthe

courseofthediseaseismoresevereinchildrenwhohavereceiveddeadvac-

cinematerial(similarlytomeasles).Thisispresumablyduetoantibodies,in

thecaseofsmallchildrenthemother’santibodiesacquiredbydiaplacental

transport.Immunosuppressedpatients,forinstance,bonemarrowrecipi-

ents,arealsoatriskforRSV.

Diagnosis.Inadditiontoserodiagnosticmethods,directdetectiontestsbased

onimmunofluorescenceorenzymeimmunoassayareavailableforpara-

myxoviruses,someofthemquitesensitive.Paramyxovirusesreplicatereadily

incellculturesfromhumantissues.

Epidemiology.Paramyxovirusesaretransmittedbydropletinfection.Gener-

alizedcontaminationlevelsinthepopulation(exceptforNipahandHendra)

arealreadyveryhighinchildhood(90%in 1 0-year-oldchildrenforparain-

fluenzavirustypes 1 – 3).

NipahandHendravirusesarezoonosesthataretransmittedtohumans

fromanimals(Nipah:pigs,Hendra:horses).Variousdifferentanimalscanbe

infectedbythesepathogens,butbats(Pteropus)appeartobethenaturalre-

servoirforbothviruses.

Prevention.Attenuatedlivevaccinesareavailableformeaslesandmumps.The

deadvaccineshouldnotbeusedduetotheaggravatingeffectmentionedabove.

Novaccineshaveasyetbeendevelopedfortheotherparainfluenzaviruses.

Rhabdoviruses

&Amongtherhabdoviruses,thelyssaviruses,genotypes 1 – 7 ,arehuman

pathogens.Theyaretransmittedbythebiteofaninfectedanimalinits

salivaandinfections,oncefullymanifest,arealwayslethal(rabies,hydro-

phobia).Thereservoirfortype 1 isprovidedbywildanimalsingeneral

(foxes,etc.),bats(sylvaticrabies),and,inAsia,dogs(urbanrabies).Types

2 – 7 arerestrictedtoEurope,Asia,Africa,andAustraliawiththeirmain

reservoirinbats.

Diagnosis:directdetectionwithIFincorneacellsandskinbiopsies,post-

mortemisolationfrombraintissues.

Prevention:duetotheweek-longandevenmonth-longincubationperiod

(exceptintypes 2 – 4),postexposureprophylacticvaccinationwithcombined

active(deadvaccine)andpassive(humanimmunoglobulin)vaccinesis

possible.Pre-exposureprophylaxisintheformofdeadvaccineisadminis-

teredtopersonsathighrisk. &

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Kayser, Medical Microbiology © 2005 Thieme