Medical Microbiology

HumansarethesolereservoirofT.vaginalis.Theparasitesaretransmitted

mainlyduringsexualintercourse.About 2 – 17 %offemaleneonatesbornof

infectedmotherscontractaperinatalinfection.

T.vaginalisishighlylabileoutsideofahost.Nonetheless,afewtropho-

zoitescansurviveforuptofivehoursinthewaterofnonchlorinatedthermal

bathsandforfiveminutesto 24 hoursintapwaterwithstandardchlorina-

tion;theyarekilledwithinafewminutesinswimming-poolwaterwithhigh

chlorineconcentrations(4 4 mg/l).Itisconceivablethatinfectionscouldbe

transmittedbywetbathingsuits,sponges,towels,etc.aswellasacquired

fromnonchlorinatedthermalbathsandpoorlymaintainedswimmingpools,

butthereisnoevidenceshowingthatthesearesignificantsourcesofinfec-

tion.

Clinicalmanifestations.Inwomen,T.vaginalisprimarilycolonizesthevagi-

nalmucosa,morerarelythatofthecervix.Inabout 20 – 50 %ofcasesthein-

fectionisasymptomatic,butvaginitiscandevelopafteranincubationperiod

oftwoto 24 days.Theinfectionresultsinproductionofapurulent,thin,yel-

lowishdischargeinwhichtrichomonads,puscells,andbacteriaarefound.

Theparasitesalsoentertheurethrainabout 75 – 90 %ofcases,wherethey

canalsocauseaninflammation,butonlyrarelyinfecttheurinarybladder

oruterus.Infectionsinmenareforthemostpartasymptomatic(50– 90 %),

buttheymayalsocauseasymptomaticurethritis,morerarelyinvolving

theprostateglandandseminalvesiclesaswell.Infectiondoesnotconferef-

fectiveimmunity.

Diagnosis.Afreshspecimenofvaginalorurethralsecretionismixedwith

physiologicalsalinesolutionandexaminedunderamicroscopefortrichomo-

nads.Thetrichomonadsarereadilyrecognizedbytheirtypicaltumbling

movements.Theroundtrichomonadforms,bycontrast,arehardlydistin-

guishablefromleukocytes.Trichomonadscanalsobeidentifiedinsmearpre-

parationsfollowingGiemsastainingorinanimmunofluorescencetestwith

monoclonalantibodies.Themostreliablediagnosticresultsareobtainedby

culturingspecimensinspecialliquidmedia.The“In-PouchTestSystem”

(BioMedDiagnostics)hasproveduseful:twoflexibleplasticchamberscon-

tainingculturemediumforcombinedmicroscopicandculturalanalysis.

Otherspecialmethodsarebasedondetectionofantigen(ELISA)orDNA

(PCR).

Therapyandprevention.Itisalwaysnecessaryforbothsexualpartnersto

receivetreatment.Effectivenitromidazolepreparationsfororalapplication—

inwomenvaginalapplication—includemetronidazole,tinidazoleandornida-

zole.Thesesubstancesarecontraindicatedinearlypregnancy.Preventive

measuresarethesameasforothervenerealdiseases.

482 9 Protozoa

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Kayser, Medical Microbiology © 2005 Thieme