Rickettsial DiseasesRickettsial Diseases

General introductionGeneral introduction

Gram-negative, obligate Gram-negative, obligate intracellular cointracellular coccobacilliccobacilli bacteriabacteria that infect mammaol that infect mammaols and arthropodss and arthropods

Rickettsiae are transmitted in the Rickettsiae are transmitted in the arthroarthropodspods,which serves as both vector and r,which serves as both vector and reservioreservior

Both Both DNADNA and and RNARNA IIs sensitive to s sensitive to antibioticantibiotic..

Category of rickettsiaCategory of rickettsia

Genus Genus

Rickettsia, Coxiella ,Orientia,Ehrlichia BartonellaRickettsia, Coxiella ,Orientia,Ehrlichia Bartonella SpeciesSpecies

Rickettsia prowazekiiRickettsia prowazekii (epidemic typhus), (epidemic typhus), RickettsRickettsia typhiia typhi (endemic typhus), (endemic typhus), Rickettsia rickettsiiRickettsia rickettsii (sp (spotted fever), otted fever), Rochalimaea quintanaRochalimaea quintana (trench feve (trench fever), r), Coxiella burnetiiCoxiella burnetii (Q fever) (Q fever)

Bilogical featuresBilogical features

Variable shape, coccobacilVariable shape, coccobacillili

Gram negativeGram negative Microcapsule and slim layeMicrocapsule and slim laye

rr Culture : in york sacs of eCulture : in york sacs of e

mbryonated eggsmbryonated eggs

Replication cycle of Rickettsia andReplication cycle of Rickettsia and OrientiaOrientia

Antigenic structureAntigenic structure

LPSLPS

Rickettsia tsutsugamushiRickettsia tsutsugamushi

Coxiella burnetiiCoxiella burnetii (Q fever) (Q fever)

LPS smoothⅠLPS smoothⅠ LPS roughⅡLPS roughⅡ Weil-Felix reacrionWeil-Felix reacrion Surface protein(SPA)Surface protein(SPA)

TransmissionTransmission

Typhus, spotted fever and trench fever are Typhus, spotted fever and trench fever are transmitted via arthropod vectors;transmitted via arthropod vectors;

Q fever is acquired via inhalation or Q fever is acquired via inhalation or ingestion of contaminated milk or food. ingestion of contaminated milk or food.

PathogenesisPathogenesis

Virulence Virulence factorsfactors: : endotoxinendotoxin, , phospholipa phospholipase Ase A, and , and slime layerslime layer

SitesSites: : vascular system producing vasculitivascular system producing vasculitiss 血管炎血管炎

Characteristic triad of symptoms: fever, heCharacteristic triad of symptoms: fever, headache and rash (no rash with Q fever). adache and rash (no rash with Q fever).

Rickettsia prowazekiiRickettsia prowazekii普氏立克次体普氏立克次体

epidemic typhusepidemic typhus average incubation periods (days):8average incubation periods (days):8 the lousethe louse Respiratory tract and conjunctivaRespiratory tract and conjunctiva Latent period: 2 weeksLatent period: 2 weeks Abrupt onset,fever,chills,headache,Abrupt onset,fever,chills,headache,

myalgia,arthralgiamyalgia,arthralgia

Rickettsia typhiRickettsia typhi地方性斑疹伤寒立克次体地方性斑疹伤寒立克次体

endemic typhusendemic typhus 7-14 days7-14 days Mice Mice the louse&fleathe louse&flea Mouth,nose and conjunctivaMouth,nose and conjunctiva Gradual onset,fever,headache,myalgia,Gradual onset,fever,headache,myalgia,

coughcough

Rickettsia tsutsugamushiRickettsia tsutsugamushi恙虫病立克次体恙虫病立克次体

Tsutsugamushi disease(scrub typhus)Tsutsugamushi disease(scrub typhus) Mice Mice tsutsugamushitsutsugamushi Black eacharBlack eachar 焦痂焦痂

Coxiella burnettiCoxiella burnetti 贝纳柯斯体贝纳柯斯体 Q feverQ fever Cow and sheepCow and sheep ticktick High resistanceHigh resistance

abrupt onset ,fever,headache,chills,myalgia,granulomatous hepatitis

chronic diaease with subacute onset ,endocarditis,hepatic dysfunction

Replication of C. burnetii Replication of C. burnetii

Generalized Life Cycle ofGeneralized Life Cycle of Dermacentor variabilis and DerDermacentor variabilis and Der

macentor andersoni Ticksmacentor andersoni Ticks

Bartonella henselaeBartonella henselae 汉赛巴通汉赛巴通体体

CSD (cat scratch disease)CSD (cat scratch disease) Cat and dogCat and dog Conjunctiva inflammation and lymph node Conjunctiva inflammation and lymph node

swellswell

EhrlichiaEhrlichia 埃里希体属埃里希体属

Ehrlichia chaffeensis: human Ehrlichia chaffeensis: human monocytotropic ehrlichiosismonocytotropic ehrlichiosis

Ehrlichia sennetsu : human Ehrlichia sennetsu : human granulocytotropic ehrlichiosisgranulocytotropic ehrlichiosis

Replication of EhrlichiaReplication of Ehrlichia 埃里希埃里希体体

Proposed life cycle for the agent of Human GranuloProposed life cycle for the agent of Human Granulo

cytic Ehrlichiosiscytic Ehrlichiosis埃里希体病埃里希体病

DiagnosisDiagnosis

The use of The use of immunofluorescent antibodiesimmunofluorescent antibodies to exa to examine a biopsy can be diagnostic. mine a biopsy can be diagnostic.

The organism can be inoculated into The organism can be inoculated into tissue cultutissue culturere and grown over 4-7 days but this is very haza and grown over 4-7 days but this is very hazardous to personnel. rdous to personnel.

The The Weil-Felix testWeil-Felix test looks for the production of se looks for the production of serum antibody that is reactive against rum antibody that is reactive against ProteusProteus OX OX19, OX2 or OXK antigens but it is not always reli19, OX2 or OXK antigens but it is not always reliable. able.

ControlControl

Sanitary:Sanitary: Arthropod and rodent control Arthropod and rodent control Immunological:Immunological: No vaccines are currently No vaccines are currently

available.available. Chemotherapeutic:Chemotherapeutic: Tetracycline or chlora Tetracycline or chlora

mphenicol are drugs of choice. mphenicol are drugs of choice.