Medical Microbiology

326 4 BacteriaasHumanPathogens

aretransmittedbythebodylouse.Preventioninvolveseradicationofthelice

withinsecticides.

B.duttonii,B.hermsii,andotherborreliaecauseendemicrelapsingfever,

whichisstillobservedtodayinAfrica,theNearandMiddleEast,andCentral

America.Thisisatickbornedisease.Hereagain,themainpreventivemeasure

iseliminationoftheinsectvectors(ticks)withinsecticides,especiallyinre-

sidentialareas.

Borreliaburgdorferi(LymeDisease)

Classification.Theetiologyofanincreaseintheincidenceofacutecasesof

arthritisamongyouthsintheLymeareaofConnecticutin 1977 wasatfirst

unclear.TheillnesswastermedLymearthritis.Itwasnotuntil 1981 that

hithertounknownborreliaewerefoundtoberesponsibleforthedisease.

TheywereclassifiedasB.burgdorferiin 1984 aftertheirdiscoverer.Analysis

ofthegenomeofvariousisolateshasrecentlyresultedinaproposaltosub-

classifyB.burgdorferisensulatointhreespecies:B.burgdorferisensustricto,

B.garinii,B.afzelii.

Morphologyandculture.Thesearethin,flexible,helicallywound,highly

motilespirochetes.TheycanberenderedvisiblewithGiemsastainingor

bymeansofdarkfieldorphasecontrastmicroscopymethods.

Theseborreliaecanbegrowninspecialculturemediumsat 358 Cforfiveto

10 days,althoughculturingtheseorganismsisdifficultandoftenunsuccessful.

Pathogenesisandclinicalpicture.Thepathogensaretransmittedbythe

biteofvarioustickspecies(seep. 60 7).Theincubation periodvaries

fromthreeto 30 days.Leftuntreated,thediseasegoesthroughthreestages

(Table4. 12 ),though individualcourses often deviate fromtheclassic

LymeDisease

Fig.4. 25 Erythema

chronicummigrans.

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Kayser, Medical Microbiology © 2005 Thieme