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   Group of bacteria that are fastidious, obligate    intracellular pathogens   They are pleomorphic & coccobacillary  ...
   Spotted Fever Group   Typhus Group   Transitional group   The Others   The outer membrane protein A (ompA) gene   ...
   Rickettsia are usually introduced into human    skin by the bite of an insect (flea or louse) or    an arachnid (tick ...
   Two of the rickettsial diseases are unique in    that humans may acquire them by direct    inhalation   Q fever (Coxi...
Disease              Rickettsial Agent   Insect Vector   Mammalian                                                        ...
Disease           Rickettsial Agent   Vector   Mammalian                                               ReservoirEpidemic t...
   very similar for all infections regardless of    species   Vasculitis caused by the invasion and    multiplication of...
   Thrombosis, occlusion, and necrosis of blood    vessel walls   Thrombocytopenia with hemorrhage   Massive capillary ...
   Rocky Mountain spotted fever   Murine (Endemic) typhus   Epidemic typhus   Q fever
   IP: 2 to 14 days   H/o exposure to tick/ close contact with pets/    Endemic area/ similar illness in family
   Initial Non-specific symptoms – Calf muscle    pain and tenderness are more common in    children.   Gastro-intestina...
FeverHeadache  Rash
Necrotic          petechiaeMaculopapular
   Rocky Mountain spotted Fever:     -Rash typically appears on 4th day as    blanching maculopapular lesions on the    e...
 Murine (fleaborne or endemic) typhus:  - Relatively mild illness with less  complications  -Rash is non-purpuric,non-con...
   Scrub typhus:     -Occurs mostly in Asian countries     -characterised by painless eschar and    “satellite lymphadeno...
   Usually does not affect children   No vector is involved   Presents as both acute or chronic forms   Endocarditis i...
   Low or normal WBC count; in the late stages    there is leucocytosis   Anemia, thrombocytopenia and elevated    serum...
   Serological evidence of infection usually not    occur earlier than second week of illness.
   Gold standard test   IgM titre >1:64   IgG titres >1:64 but <1:125 suggests    previous infection   A single titer ...
   Slide agglutination test   Tests the presence of antigenic cross-    reactivity between Rickettsia spp. and certain  ...
Rickettsia Agent    AntigenSpotted Fever Group                      OX 2 (Pr.vulgaris)Typhus Group, RMSF    OX 19 (Pr.vulg...
   Complement fixation   Latex agglutination   Microagglutination   Immunoperoxidase assay
   Drug of choice for all ages –    Doxycycline(4 mg/kg/day divided every 12 hr    PO or IV, maximum 200 mg/day)   Chlor...
   Azithromycin, Clarithromycin   Fluoroquinolones   Rifampicin    -Found to be more effective in typhus groups.
   Patient coming from endemic area.   H/O contact-pets/ h/o tick bite.   Classical triad   Rash without coryza.   he...
   When applied to the patients presenting with    fever of unknown source, a clinical score of    14 or more on the prop...
Rickettsial infections
Rickettsial infections
Rickettsial infections
Rickettsial infections
Rickettsial infections
Rickettsial infections
Rickettsial infections
Rickettsial infections
Rickettsial infections
Rickettsial infections
Rickettsial infections
Rickettsial infections
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Rickettsial infections

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A comprehensive description about various rickettsial infections encountered in Pediatrics

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Transcript of "Rickettsial infections"

  1. 1.  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. 2.  Spotted Fever Group Typhus Group Transitional group The Others The outer membrane protein A (ompA) gene is present in spotted fever but not typhus group organisms
  3. 3.  Rickettsia are usually introduced into human skin by the bite of an insect (flea or louse) or an arachnid (tick or mite) These arthropods serve as both host and vector to the rickettsia and reside on the reservoir animals (dogs, mice, rats, and flying squirrels)
  4. 4.  Two of the rickettsial diseases are unique in that humans may acquire them by direct inhalation Q fever (Coxiella burnetii) Epidemic typhus (Rickettsia prowazekii)
  5. 5. Disease Rickettsial Agent Insect Vector Mammalian ReservoirIndian tick typhus R.conorii Tick Dog/RodentsRMSF R.rickettsi Tick Dog/RodentsRickettsial pox R.akari Mite Mice
  6. 6. Disease Rickettsial Agent Vector Mammalian ReservoirEpidemic typhus R.prowazeki Louse HumansMurine typhus R.typhi Flea RodentScrub typhus R.tsusugamushi Mite Rodent
  7. 7.  very similar for all infections regardless of species Vasculitis caused by the invasion and multiplication of the organism in the endothelial and smooth muscle cells of the blood vessels
  8. 8.  Thrombosis, occlusion, and necrosis of blood vessel walls Thrombocytopenia with hemorrhage Massive capillary leakage into the interstitial spaces results in edema, hypovolemia, hypotension, and adult respiratory distress syndrome (ARDS) Encephalitis, myocarditis, & nephritis are the common clinical consequences Hyponatremia is due to ADH response
  9. 9.  Rocky Mountain spotted fever Murine (Endemic) typhus Epidemic typhus Q fever
  10. 10.  IP: 2 to 14 days H/o exposure to tick/ close contact with pets/ Endemic area/ similar illness in family
  11. 11.  Initial Non-specific symptoms – Calf muscle pain and tenderness are more common in children. Gastro-intestinal symptoms are more commonly associated Skin rash: 2-4 days after onset of illness.
  12. 12. FeverHeadache Rash
  13. 13. Necrotic petechiaeMaculopapular
  14. 14.  Rocky Mountain spotted Fever: -Rash typically appears on 4th day as blanching maculopapular lesions on the extremities Louse borne or Epidemic typhus: -Rash first appears in axillary folds then involving the trunk and extremities. - Brill-Zinsser disease
  15. 15.  Murine (fleaborne or endemic) typhus: - Relatively mild illness with less complications -Rash is non-purpuric,non-confluent,less extensive -History of a flea bite and the presence ofrats in the house support the diagnosis butthis is only reported 30% of the time.
  16. 16.  Scrub typhus: -Occurs mostly in Asian countries -characterised by painless eschar and “satellite lymphadenopathy” Rickettsial pox: -best known because of its association with a varicelliform rash.
  17. 17.  Usually does not affect children No vector is involved Presents as both acute or chronic forms Endocarditis in chronic variety Bioterrorist threat?
  18. 18.  Low or normal WBC count; in the late stages there is leucocytosis Anemia, thrombocytopenia and elevated serum transaminases Hyponatremia CSF analysis is usually normal; rarely mononuclear plecytosis (<300 cells/micro L)
  19. 19.  Serological evidence of infection usually not occur earlier than second week of illness.
  20. 20.  Gold standard test IgM titre >1:64 IgG titres >1:64 but <1:125 suggests previous infection A single titer is neither sensitive (patients can die before seroconversion) nor specific (an elevated titer can represent prior infection) ELISA – available in India and is the preferred diagnosis at present
  21. 21.  Slide agglutination test Tests the presence of antigenic cross- reactivity between Rickettsia spp. and certain serotypes of non-motile Proteus spp., suffers from poor sensitivity and specificity, with a recent study showing an overall sensitivity as low as 33% and specificity of 46%.
  22. 22. Rickettsia Agent AntigenSpotted Fever Group OX 2 (Pr.vulgaris)Typhus Group, RMSF OX 19 (Pr.vulgaris)Scrub typhus OX K (Pr.mirabilis)
  23. 23.  Complement fixation Latex agglutination Microagglutination Immunoperoxidase assay
  24. 24.  Drug of choice for all ages – Doxycycline(4 mg/kg/day divided every 12 hr PO or IV, maximum 200 mg/day) Chloramphenicol – Allergy to Doxycycline, Pregnant women (50-100 mg/kg/day divided 6th hourly, max 3 g/day) Continued for minimum of 5-7 days and for atleast 3 days until patient is afebrile.
  25. 25.  Azithromycin, Clarithromycin Fluoroquinolones Rifampicin -Found to be more effective in typhus groups.
  26. 26.  Patient coming from endemic area. H/O contact-pets/ h/o tick bite. Classical triad Rash without coryza. hepatosplenomegaly,edema,gangrene,anemia,thrombocyto penia Fever,rash,altered sensorium, convulsions PUO and not responding to routine antibiotics
  27. 27.  When applied to the patients presenting with fever of unknown source, a clinical score of 14 or more on the proposed scoring system has very high sensitivity and specificity for the diagnosis of spotted fever group of rickettsial diseases.

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