Medical Microbiology

&Treatmentofacutedisease.Theclinicalsymptomsofmalariaarecaused

bytheasexualformsintheerythrocyticschizogoniccycle.Aclinicalcureis

thusachievedbyeliminatingtheseformsorstageswithso-calledschizonti-

cides(Table9. 6 ).Theantimalarialspreferredinthisindicationarefast-acting

schizonticidessuchasquinine,mefloquine,andhalofantrine(insomecoun-

triesartemisininderivativesaswell)aswellasquininecombinedwithdoxy-

cycline(especiallyincomplicatedtropicalmalaria)andvariouscombined

preparations(Table9. 6 ).Someoftheabovesubstancesarealsoeffective

againstchloroquine-resistantandmultiresistantPlasmodiumstrains.Chloro-

quine,aformermainstayofmalariatherapy,hasnowlostsomeofitsimpor-

tanceduetowidespreaddrugresistanceofplasmodia.

&Preventionofrelapses(radicalcure).Agentseffectiveagainstblood

schizontsdonoteliminatethelatenttissueforms(hypnozoites)ofPlasmo-

diumvivaxandPlasmodiumovaleintheliver.Topreventrelapses,tissue

formscanbeeliminatedwithprimaquineaftertheacutetherapyiscom-

pleted(Table9. 6 ).ThistherapyisnotrequiredforinfectionsbyP.falciparum

andP.malariaesincetheydonotproducehypnozoites.

Plasmodium 533

Table9. 6 Continued:AntimalarialAgents(aselection)

Chemicalgroup Spectrumofefficacy

anddrug

(P):usedforprophylaxis Asexual

bloodstages

Game-

tocytes

Liver

schizonts

Hypnozoites

ofP.vivax,

P.ovale

Drugcombinations

Atovaquone+proguanil(P) + VOM + –

Artemether+lumefantrine + + ni –

Chloroquine+proguanil(P) + VOM F –

Sulfadoxine^2

+pyrimethamine^3

+ VOM – –

Sulfadoxine^2

+pyrimethamine^3

+mefloquine

+ VOM – –

(^1) Effectiveness:+:effective;+/–:moderatelyeffective;?:questionablyeffective;
–:ineffective.
F:effectiveagainstP.falciparum;VOM:effectiveagainstP.vivax,P.ovale,P.malariae;
ni:noinformation
(^2) Dihydropteroatesynthetaseinhibitors(=sulfonamidesandsulfones)
(^3) Dihydrofolatereductaseinhibitors(=antifolates)
9
Kayser, Medical Microbiology © 2005 Thieme