Medical Microbiology

Nematoda(Roundworms) 601

&Intestinalphase:incubationperiodofonetosevendays.Symptoms:nau-

sea,vomiting,gastrointestinaldisorderswithdiarrhea,mildfever,andother

symptoms.Aninapparentcourseisalsopossible.

&Extraintestinalphase:incubationperiodofsevenormoredays.Symp-

tomscausedbyinvasionofbodytissuesbyTrichinellalarvae:myositis

withmusclepainandstiffness,respiratoryandswallowingdifficulties,fever,

edemasoneyelidsandface,cutaneousexanthema.Fearedcomplicationsin-

cludemycocarditisandmeningoencephalitis.Furthercharacteristicfeatures

arebloodeosinophilia,raisedactivityofserumlactatedehydrogenase,myo-

kinaseandcreatinephosphokinase,andcreatinuria.Thisphaselastsabout

onetosixweeks.Itisfrequentlyfollowedbyrecovery,butrheumatoid

andothersymptomscanalsopersist(e.g.,cardiacmuscledamage).Lethal

outcomeisrare.

Diagnosis.Diagnosisduringtheintestinalphaseisdifficultandonlyrarely

trichinellaecanbefoundinstoolorduodenalfluid.Duringtheextraintestinal

phase,Trichinellalarvaearedetectableinmusclebiopsies(eitherbymicro-

scopyinpresspreparations,histologicallyorbyPCR-basedDNAdetection).

Beginninginthethirdweekp.i.serumantibodiesappear(Table 11. 5 ,p.626).

Clinicalchemistry(seeabove)furnishesfurtherdiagnosticdata.

Therapyandprevention.Therecommendeddrugsfortherapyaremeben-

dazoleoralbendazoleincombinationwithprednisolone(toalleviateallergic

andinflammatoryreactions)(WHO, 1 995).Heatexceeding 808 Ckillstrichi-

nellaeinmeat.Thesafestmethodsaretoboilorfrythemeatsufficiently

(deep-freezingmaybeunreliable,seeabove!).Importantdiseasecontrol

measuresincludeprophylacticinspectionofdomesticandwildanimal

meatforTrichinellainfectionandnotfeedingrawmeatwastestopiglivestock

andothersusceptibledomesticanimals.

InfectionsCausedbyNematodalLarvae

&LarvamigransexternaandLarvamigransinternaarediseasescausedby

migratingnematodelarvae.Thefirst(externa)isaskindisease,usually

causedbyzoonotichookwormsorStrongyloidesspecies.Inthesecond

type(interna),nematodelarvaemigrateintoinnerorgans,e.g.,intoxocarosis.

Intoxocarosistheinfectionresultsfromperoralingestionofinfectiveeggsof

roundwormsofthegenusToxocarathatarereleasedtotheenvironmentin

thefecesofdogs,foxes,andcats(infectionriskforchildrenoncontaminated

playgrounds!).Inhumans,migratingToxocaralarvaecancausedamageto

liver,lungs,CNS,andeyes.Additionaldiseasescausedbynematodelarvae

includeanisakiosis,angiostrongylosis,anddirofilariosis. &

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Kayser, Medical Microbiology © 2005 Thieme