Medical Microbiology

466 8 VirusesasHumanPathogen

Pathogenesisandclinicalpicture.

&Theparainfluenzavirusescauseflulikeinfections,mainlyinsmallchil-

dren,whichoccasionallyprogresstobronchitisorevenpneumonia.Occa-

sionally,adangerouscroupsyndromedevelops.Bacterialsuperinfections

arefrequent,asaretheusuallyharmlessreinfections.

&Inmumpsvirusinfectionsthevirusfirstreplicatesintherespiratory

tract,thencausesaviremia,afterwhichaparotitisisthemaindevelopment

aswellas,fairlyfrequently,mumpsmeningitis.Complicationsincludeinfec-

tionofvariousglandularorgans.Orchitiscanoccurinpostpubertyboyswho

contractmumps.

&Measles.Thepathogenesisofmeasleshasnotbeenfullyexplained.Itis

assumedthatthevirus,followingprimaryreplicationinlymphoidtissues,is

distributedhematogenouslyintwoepisodes.Thereaftertheoralmucosadis-

playsanenanthemandthetinywhite“Koplik’sspots.”Thenthefeveronce

againrisesandthetypicalmeaslesexanthemmanifests(Fig.8. 17 ).Possible

complicationsincludeotitisintheformofabacterialsuperinfectionaswell

aspneumoniaandencephalitis.Ararelatesequelofmeasles(onecaseper

millioninhabitants)issubacutesclerosingpanencephalitis(SSPE)inwhich

nucleocapsidsaccummulateinbraincells,wherebyfewornoviralprogeny

areproducedforlackofmatrixprotein.Thisdiseaseoccursbetweentheages

ofoneand20,involveslossofmemoryandpersonalitychanges,andusually

resultsindeathwithinsixto 12 months.

&NipahandHendravirusinfectionsarezoonosesendemictoSoutheast

Asia(Nipah)orAustralia(Hendra).Bothinfectionsresultinencephalitis

withrelativelyhighlethalityrates(upto 40 %)andinsomecasessevere

interstitialpneumonias.

MeaslesExanthem

Fig.8. 17 Thetypicalexanthemmani-

festsduring whatispresumablythe

second hematogenous disseminative

episodeofthemorbilliviruses.

8

Kayser, Medical Microbiology © 2005 Thieme