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.