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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
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
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
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.