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