Medical Microbiology

440 8 VirusesasHumanPathogen

Diagnosis.Detectionbymeansofelectronmicroscopyorantigenassayin

stool.

Epidemiology.Two-thirdsoftheadultpopulationinthetemperatezone

carryantibodiestotheNorwalkvirus.SRSVareregularlyimplicatedinminor

epidemicsandfamilyoutbreaks.ThetransmissionrouteoftheNorwalkvirus

hasbeendescribed:inadditiontothefecal-oralroute,wateranduncooked

foodsareinvolved.

HepatitisEViruses

Pathogen.AninfectiousinflammationoftheliverendemictoAsia,Central

America,andpartsofAfricaisapparentlytransmittedbythefecal-oralroute.

TheRNAgenomeoftheculpritagenthasnowbeensequencedandthevirus

inquestion,thehepatitisEvirus,hasbeenclassifiedwiththecaliciviruses.It

occursinatleast 13 variantsdividedintothreegroups.In-vitroculturingof

HEVhasnotsucceededtodate.

Pathogenesisandclinicalpicture.TheclinicalcourseofhepatitisEinfections

tendstobebenignandresemblesthatofhepatitisA.Itshowsnochronicity.

However,infectionsinthethirdtrimesterofpregnancyhavealethalityrate

of 10 – 40 %.

Diagnosis.Theantibodiescanbedetectedbymeansofanenzymeimmu-

noassay.Apparentlyduetocross-reactionswithothercaliciviruses,thespe-

cificityoftheresultsisuncertain.Adiagnosisisoftenarrivedatbasedon

clinicalevidenceandmedicalhistory(traveltoendemicareas).

Epidemiology.HEVcausesrepeatedoutbreaksofconsiderabledimensions

inthepartsoftheworldmentionedabove.Theinfectionscanbetracedto

contaminateddrinkingwater.HepatitisEisimportedtocentralEuropeas

atraveler’sinfection,althoughapparentlylessfrequentlythanhepatitisA.

Nospecificprophylacticmeasuresexist.

Togaviruses

&Thetogavirusfamily(Togaviridae)comprisestwogenera.Alphavirusinfec-

tionsaretransmittedbyarthropodsandareimportedtocentralEuropemainly

bytravelerstotropicalandsubtropicalcountries.Theirclinicalpicturesare

variable,butalmostalwaysincludejointpain(arthralgias).Themostimportant

representativeofthegenusRubivirusistherubellavirus,thecausativeagent

inGermanmeasles.Thisnormallyharmlesschildhooddiseasecancausesevere

embryopathiesduringthefirsttrimesterofpregnancy. &

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Kayser, Medical Microbiology © 2005 Thieme