Medical Microbiology

Epidemiology.ThereareepidemiologicaldifferencesbetweenT.gambiense

andT.rhodesiense(Table9. 2 ),themainonebeingthatT.rhodesiensepersists

inalatentenzooticcycleinwildanddomesticanimalsandisnormallytrans-

mittedbyGlossinafromanimaltoanimal,morerarelytohumans.T.gam-

biense,ontheotherhand,istransmittedmainlyfromhumantohumanby

thetsetseflies,althoughvariousanimalspecieshavealsobeenidentified

asreservoirhostsforT.gambiensestrains.

Clinicalmanifestations.Sleepingsicknessis,intheinitialphase,afebrile,

generalizeddiseasewithlymphadenopathyandislatercharacterizedby

meningoencephaliticsymptoms.Theinfectionrunsatwo-stage course:

thefebrile-glandularorhemolymphaticstage 1 andthemeningoencephalitic

stage2.Thedifferenceistherapeuticallysignificant.Instage 1 ,thetrypano-

somesmultiplyinthetissuefluidattheinoculationsite.Within 2 – 4 days

aninflammatory,edematousswellingcandevelop—theprimarylesionor

“trypanosomechancre,”whichthendisappearswithinaboutthreeweeks.

Withinaperiodofapproximatelytwoweeksthetrypanosomesenterthe

bloodstreamandlymphaticsystem.Later,inthesecondstage,theyalso

invadethecentralnervoussystem.Table9. 3 summarizesfurtherdetailsof

thedisease.

488 9 Protozoa

Table9. 2 EpidemiologicalDifferencesbetweenTrypanosomagambienseand

T.rhodesiense

Parameter T.gambiense T.rhodesiense

Distribution: WesternandcentralAfrica EasternandcentralAfrica

Vector: Glossinapalpalisgroup:

Moistbiotopes

G.morsitansgroup:

Savannabiotopes

Sitesoftransmission:

&Frequentlyfocal: Atrivers,lakes,

wateringholes,etc.

&Lesslocalized: Inmoistforestareas Savannas

Dominantcycle: Human!human Wildanddomesticruminants,

otherwildanimals!humans

Reservoirhosts

(forcertain

Trypanosomastrains)

Pigs,cattle,sheep,dogs,

asmallnumberofantelope

species

Antelopespecies,cattle,

sheep,goats,warthogs,lions,

hyenas,dogs,etc.

9

Kayser, Medical Microbiology © 2005 Thieme