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RICKETTSIAORIENTIA
EHRLICHIA ANAPLASMA
COXIELLABARTONELLA
General introduction
Gram-negative, obligate intracellular coccobacilli bacteria that infect mammaols and arthropods
Rickettsiae are transmitted in the arthropods,which serves as both vector and reservior
Both DNA and RNA Is sensitive to antibiotic.
Category of rickettsia
Genus Rickettsia, Coxiella ,Orientia,Ehrlichia Bartonella Species Rickettsia prowazekii (epidemic typhus),
Rickettsia typhi (endemic typhus), Rickettsia rickettsii (spotted fever), Rochalimaea quintana (trench fever), Coxiella burnetii (Q fever)
Bilogical features
Variable shape, coccobacilli
Gram negative Microcapsule and slim
layer Culture : in york sacs of
embryonated eggs
Antigenic structure
LPS Rickettsia tsutsugamushi Coxiella burnetii (Q fever) LPS smoothⅠ LPS roughⅡ Weil-Felix reacrion Surface protein(SPA)
Transmission
Typhus, spotted fever and trench fever are transmitted via arthropod vectors;
Q fever is acquired via inhalation or ingestion of contaminated milk or food.
Pathogenesis
Virulence factors: endotoxin, phospholipase A, and slime layer
Sites: vascular system producing vasculitis血管炎
Characteristic triad of symptoms: fever, headache and rash (no rash with Q fever).
Rickettsia prowazekii普氏立克次体 epidemic typhus average incubation periods (days):8 the louse Respiratory tract and conjunctiva Latent period: 2 weeks Abrupt onset,fever,chills,headache, myalgia,arthralgia
Replication cycle of Rickettsia and Orientia
Rickettsia typhi地方性斑疹伤寒立克次体 endemic typhus 7-14 days Mice the louse&flea Mouth,nose and conjunctiva Gradual onset,fever,headache,myalgia, cough
Rickettsia tsutsugamushi恙虫病立克次体 Tsutsugamushi disease(scrub typhus) Mice tsutsugamushi Black eachar焦痂
Coxiella burnetti贝纳柯斯体 Q fever Cow and sheep tick High resistance
abrupt onset ,fever,headache,chills,myalgia,granulomatous hepatitis
chronic diaease with subacute onset ,endocarditis,hepatic dysfunction
Replication of C. burnetii
Generalized Life Cycle of Dermacentor variabilis and
Dermacentor andersoni Ticks
Bartonella henselae汉赛巴通体 CSD (cat scratch disease) Cat and dog Conjunctiva inflammation and lymph node
swell
Ehrlichia埃里希体属 Ehrlichia chaffeensis: human
monocytotropic ehrlichiosis Ehrlichia sennetsu : human granulocyto
tropic ehrlichiosis
Replication of Ehrlichia埃里希体
Proposed life cycle for the agent of Human Granulocytic Ehrlichiosis埃里希体病
Diagnosis
The use of immunofluorescent antibodies to examine a biopsy can be diagnostic.
The organism can be inoculated into tissue culture and grown over 4-7 days but this is very hazardous to personnel.
The Weil-Felix test looks for the production of serum antibody that is reactive against Proteus OX19, OX2 or OXK antigens but it is not always reliable.
Control
Sanitary: Arthropod and rodent control Immunological: No vaccines are
currently available. Chemotherapeutic: Tetracycline or
chloramphenicol are drugs of choice.