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Rickettsial Diseases

Rickettsial Diseases. 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 I s sensitive to antibiotic.

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Rickettsial Diseases

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  1. Rickettsial Diseases

  2. General introduction • Gram-negative, obligate intracellular coccobacillibacteria 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.

  3. 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)

  4. Bilogical features • Variable shape, coccobacilli • Gram negative • Microcapsule and slim layer • Culture : in york sacs of embryonated eggs

  5. Replication cycle of Rickettsia andOrientia

  6. Antigenic structure • LPS Rickettsia tsutsugamushi Coxiella burnetii (Q fever) LPSⅠ smooth LPSⅡ rough Weil-Felix reacrion • Surface protein(SPA)

  7. 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.

  8. 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).

  9. 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

  10. 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

  11. Rickettsia tsutsugamushi恙虫病立克次体 • Tsutsugamushi disease(scrub typhus) • Mice • tsutsugamushi • Black eachar焦痂

  12. Coxiella burnetti贝纳柯斯体 • Q fever • Cow and sheep • tick • High resistance

  13. Replication of C. burnetii

  14. Generalized Life Cycle ofDermacentor variabilis and Dermacentor andersoni Ticks

  15. Bartonella henselae汉赛巴通体 • CSD (cat scratch disease) • Cat and dog • Conjunctiva inflammation and lymph node swell

  16. Ehrlichia埃里希体属 • Ehrlichia chaffeensis: human monocytotropic ehrlichiosis • Ehrlichia sennetsu : human granulocytotropic ehrlichiosis

  17. Replication of Ehrlichia埃里希体

  18. Proposed life cycle for the agent of Human Granulocytic Ehrlichiosis埃里希体病

  19. 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.

  20. Control • Sanitary: Arthropod and rodent control • Immunological: No vaccines are currently available. • Chemotherapeutic: Tetracycline or chloramphenicol are drugs of choice.

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