Medical Microbiology

30 1 GeneralAspectsofMedicalMicrobiology

Continued:OtherZoonoses

Helminthiczoonoses Cercarialdermatitis;clonorchiosis;cysticercosis;dicro-

coeliosis;diphyllobothriosis;echinococcosis;fasciolosis;

hymenolepiosis;larvamigransinterna;opisthorchiosis;

paragonimosis;schistosomosis(bilharziosis);taeniosis;

toxocariosis;trichinellosis.

Zoonosescaused Fleainfestation;larvamigransexterna;miteinfestation;

byarthropods sandfleainfestation.

SourcesofInfection

Everyinfectionhasasource(Table 1. 11 ).Theprimarysourceofinfectionis

definedasthelocationatwhichthepathogenispresentandreproduces.Sec-

ondarysourcesofinfectionareinanimateobjects,materials,orthirdper-

sonscontributingtotransmissionofpathogensfromtheprimarysourceto

disposedpersons.

Table 1. 11 PrimarySourcesofInfection

Sourceofinfection Explanation

Infectedperson Themostimportantsource;asarule,pathogensare

excretedbytheorgansystemthroughwhichtheinfection

entered;therearesomeexceptions

Carriersduringincuba-

tion

Excretionduringincubationperiod;typicalofmanyviral

diseases

Carriersinconvales-

cence

Excretionafterthediseasehasbeenovercome;typicalof

entericsalmonelloses

Chroniccarriers Continuedexcretionforthreeormoremonths(evenyears)

afterdiseasehasbeenovercome;typicaloftyphoidfever

Asymptomaticcarriers Theycarrypathogenicgermsonskinormucosawithout

developing“infection”

Animalcarriers Diseasedorhealthyanimalsthatexcretepathogenicgerms

Environment Soil,plants,water;primarysourceofmicroorganismswith

naturalhabitatinthesebiotopes

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Kayser, Medical Microbiology © 2005 Thieme