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Rickettsia

Rickettsia. Group of bacteria that are fastidious, obligate intracellular pathogens They are pleomorphic & coccobacillary • The organisms will not show up on Gram stain, but can be seen when either Gimenez or Giemsa stains are used. Why Rocky Mountain Spotted Fever?. Prototype rickettsiosis

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Rickettsia

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  1. Rickettsia • Group of bacteria that are fastidious, obligate intracellular pathogens • They are pleomorphic & coccobacillary • The organisms will not show up on Gram stain, but can be seen when either Gimenez or Giemsa stains are used

  2. Why Rocky MountainSpotted Fever? • Prototype rickettsiosis • Main reason for deaths?

  3. Etiology: Invertebrates 1. Rickettsia rickettsiae 2. Ticks (tolerate infection) • Dermacentor andersonii, D. variabilis (“hard”) • Transstadial, transovarial transmission

  4. Etiology Microbe R. rickettsii Vector Tick Reservoir Rodents Host Intruder

  5. Person • Outdoor activity • Peak age 5-9 • Mortality highest in elderly

  6. Development of illness • Inoculation • Rickettsemia • Endothelial localization • Vasculitis

  7. Clinical recognition • Rash • Fever • Headache • Other

  8. Fever and headache • Fever • 102 to 105 degrees • 2 to 3 weeks without treatment • Headache: severe

  9. Clinical recognition • Rash • Fever • Headache • Other

  10. Clinical recognition • Rash • Fever • Headache • Other

  11. Laboratory diagnosis • Skin biopsy: immunofluorescent stain • Serology • Weil-Felix archaic • Immunofluorescent antibody • No growth on routine culture

  12. Prevention • Vector control impractical • Vaccine unavailable • So . . . caution outdoors • Long clothing • Skin inspection

  13. Rocky Mountain Spotted Fever • Physician suspicion crucial • R. rickettsii, ticks • Not just Rockies • Vasculitis • Rash, fever, headache • Doxycycline, look for ticks

  14. Rickettsiae & spirochetes • Rocky Mountain Spotted Fever • Rickettsial biology • Other rickettsioses • Spirochetes

  15. Order Rickettsiales • Family Rickettsiaceae • Tribe Rickettsiae • Genus Rickettsia • Genus Coxiella • Genus Rochalimaea • Family Bartonellaceae

  16. Spotted Fever Group • Rocky Mountain spotted fever – Rickettsia rickettsii • Rickettsial pox – Rickettsia akari • Canadian typhus – Rickettsia canada • Mediterranean spotted fever – Rickettsia conorii • Siberian tick typhus – Rickettsia siberica • Queensland tick typhus – Rickettsia australis • Murine typhus (also known as endemic typhus and fleaborne typhus) – Rickettsia mooseri (typhi) • • Epidemic typhus (also known as Brill- Zinsser disease and louseborne typhus) – Rickettsia prowazekii • • Scrub typhus (or Chigger fever) – Rickettsia tsutsugamushi

  17. Rickettsial groups • Spotted fever group • Rocky Mountain Spotted Fever • Other spotted fevers • Rickettsialpox • Typhus group • Epidemic typhus, Brill-Zinsser • Murine, scrub typhus

  18. Typical rickettsial illness • Inoculation eschar (exception: Rocky Mountain Spotted Fever) • Rickettsemia • Endothelial growth • Vasculitis • 1-2 week incubation • Rash, fever, headache

  19. Rickettsial diagnosis • Must suspect clinically • Immunoflorescent stained skin biopsy • Weil-Felix passé • Serology usually (but delay in getting results) • Isolation hazardous • Rule out others

  20. Rickettsial control • Public health • Reporting • Vector/reservoir • No vaccines

  21. Rickettsial diseases other than Rocky Mountain Spotted Fever • Other spotted fevers (in other parts of world) • Rickettsialpox (urban, from mice and mites) • Typhus group (epidemic typhus from lice)

  22. Other rickettsioses • Vector (often tick) • Eschar, rickettsemia • Vasculitis, serologic test • Includes spotted fevers, rickettsialpox, typhus group

  23. Typical Eschar at Tick Bite Site

  24. Rickettsiae & spirochetes • Rocky Mountain Spotted Fever • Rickettsial biology • Other rickettsioses • Spirochetes

  25. Vincent’s infection/Trench mouthNecrotizing ulcerative gingivitis • Synergistic gum infection • Occurs in poor oral hygiene, malnutrition, immunocompromise • Penicillin, oral hygiene

  26. B. recurrentis Lice Human-lice E. Africa, Andes Borrelia spp Ornithodoros tick Human intruder Worldwide: High, warm, humid Relapsing FeverEpidemic Endemic

  27. Relapsing fever pathogenesis • Spirochetemia • Sequestration • Antigenic modification • Widespread (liver, spleen, CNS, heart, GI, kidney)

  28. Relapsing fever presentation • Abrupt fever, malaise, headache • Arthralgia, cough, photophobia • Conjunctival suffusion • Petechiae • Abdominal tenderness

  29. Relapsing fever • Recovery in 3-6 days • Relapse in 7-10 days • Untreated, 40% die • Blood smear positive 70% • Tetracycline, chloramphenicol

  30. Lyme disease, United States

  31. Lyme disease cases by month, US, 1999

  32. Erythema chronicum migrans

  33. Lyme diagnosis and treatment • Clinical, with special serology • Treatment depends on stage • Doxycycline, amoxicillin, cefuroxime • IV penicillin or ceftriaxone (later)

  34. Tick repellent • DEET • Skin, clothing • CNS toxicity (directions) • Permethrin: Clothing

  35. Key points: Lyme disease • Tickborne B. burgdorferi • Local: Erythema migrans • Dissem: Heart, nerve, joint • Persist: Fatigue, joint • Doxycycline, ceftriaxone

  36. Frontiers of prevention • Vaccine: Withdrawn • Tick avoidance

  37. Many spirochetes tickborne • Not tickborne • Syphilis: Sex • Leptospirosis: Animal urine; early conjunctival suffusion, later liver & kidneys • Tickborne: Borrelia relapsing fever, change antigens & relapse

  38. Lyme (& Syphilis) Initial rash: Erythema chron. mig. 2º stage: Nerves, heart, joints Late stage: Arthritis, fatigue Treatment: Penicillin, tetracycline Spirochetal disease parallels

  39. Rickettsia and spirochetes • Rocky Mountain Spotted Fever • Headache, rash, fever • Tickborne • No growth on routine culture • Doxycycline

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