Medical Microbiology

Recommendationstoavoidinfection:hygienicprecautionswhenhand-

lingoocystsexcreters(humans,animals)anddiagnosticspecimens,improve-

mentofcommunitydrinkingwaterprocessinginsomeareas.Theoocystsare

resistanttothestandardconcentrationsofchlorineorozoneindrinking

water,butcanbekilledbyheat(> 708 C)inafewminutes.

Plasmodium

Causativeagentofmalaria

&Malaria,themostfrequenttropicalparasitosis,isalsoofmedicalsignifi-

canceincentralEuropeandotherregionsasatravelers‘disease.Theinfection

iscausedbyplasmodia(Plasmodiumvivax,P.ovale,P.malariae,P.falciparum)

transmittedbythebiteofAnophelesmosquitoes.Aninfectioninitiallypre-

sentsinnonspecificsymptoms(headache,fatigue,nausea,fever).Untreated

malariatropica(causedbyP.falciparum)canquicklydeveloptoalethal

outcome.Therefore,itisimportanttoobtainanetiologicaldiagnosisas

quicklyaspossiblebymicroscopicdetectionoftheparasitesintheblood,

andtoinitiateeffectivetreatment.Prophylacticmeasuresareessentialfor

travelerstoregionswheremalariaisendemic(preventionofmosquitobites,

chemoprophylaxis). &

Occurrence.Malariaisoneofthemostsignificantinfectiousdiseasesofhu-

mans.AccordingtotheWHO(20 0 0, 200 4),thediseaseiscurrentlyendemic

inmorethan 100 countriesorterritories,mainlyinsub-SaharanAfrica,Asia,

Oceania,CentralandSouthAmerica,andintheCaribbean.About2.4billion

people(40%oftheworld’spopulation)liveinmalariousregions.Fig.9. 16

showsthegeographicdistributionofmalaria(WHO, 200 0).Theannualin-

cidenceofmalariaworldwideisestimatedtobe 300 – 500 millionclinical

cases,withabout 90 %oftheseoccurringinsub-SaharanAfrica(mostly

causedbyP.falciparum).Malariaaloneorincombinationwithotherdiseases

killsapproximately 1. 1 – 2.7millionpeopleeachyear,including 1 millionchil-

drenundertheageoffiveyearsintropicalAfrica.About 7000 casesofim-

portedmalariawerereportedinEuropeintheperiodfrom 1985 to 1 995,

wherebythedataareincomplete.

Parasites.FourPlasmodiumspeciesinfecthumansandcausedifferenttypes

ofmalaria:

&Plasmodiumvivax:tertianmalaria(malariatertiana),

&Plasmodiumovale:tertianmalaria(malariatertiana),

520 9 Protozoa

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Kayser, Medical Microbiology © 2005 Thieme