Medical Microbiology

Rickettsia,Coxiella,Orientia,andEhrlichia 333

demicsareoccasionallyseenworldwide.Thesourcesofinfectionaredis-

easedlivestockthateliminatethecoxiellaeinurine,milk,orthroughthebirth

canal.Humansandanimalsareinfectedbyinhalingdustcontainingthe

pathogens.Specificpreventivemeasuresaredifficulttorealizeeffectively

sinceanimalsshowingnosymptomsmaybeexcreters.Activevaccination

ofpersonsexposedtotheseinfectionsintheirworkprovidesacertaindegree

ofimmunizationprotection.

Until 1987 ,ehrlichioseswerethoughttooccuronlyinanimals.Tickborne

Ehrlichiainfectionsinhumanshavenowbeenconfirmed.

Table4. 14 PathogensandClinicalPictureoftheEhrlichioses

Pathogen Vector/host Disease Clinicalpicture

Ehrlichia

chaffeensis

Ticks/deer,

dog

Humanmono-

cytotrophic

ehrlichiosis

(HME);

monocytesare

maintargetof

pathogen

Allehrlichiosespresentasmild

tooccasionallyseveremono-

nucleosis-likemultisystem

diseasewithheadache,fever,

myalgiasleukopenia,thrombo-

cytopenia,anaemia,andraised

transaminases. 20 – 30 %show

varioussymptomsinthegastro-

intestinaltractand/orrespiratory

tractand/orCNS.

Incubationtimebetween

5–1 0 days.

Antibioticsofchoicearethe

tetracyclines.

Cultivationfrombloodusingcell

culturesexhibitslowsensitivity.

Moleculartechniques(PCR)

betterforpathogendetection.

Useindirectimmunofluores-

cenceforantibodytiters.

Ehrlichia

ewingii

and

Anaplasma

phagocytophi-

lum

Ticks/dogs,

horse,other

animals

Humangranulo-

cytotrophic

ehrlichiosis

(HGE);granulo-

cytesaremain

targetof

pathogen

Neorickettsia

sennetsu

Hostunknown;

perhapsfish.

Transmission

fromeatingraw

fish

Sennetsufever;

occursinSouth-

eastAsia(Japan)

4

Kayser, Medical Microbiology © 2005 Thieme