Typhus: the Rickettsial Disease

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Typhus

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Typhus: the Rickettsial Disease

  1. 1. TyphusThe Rickettsial Disease
  2. 2. Rickettsiae:• parasitic bacteria• Obligate intracellular parasite• Bigger than virus• Smaller than bacteria• Carried by host arthropods• Invade human mononuclear cells, neutrophils, bld vessel endotheliums
  3. 3. Pathology• Rickettsia are transmitted to humans by the bite of infected arthropod vector• Multiply at the site of entry and enter the blood stream• Widespread vasculitis and endothelial proliferation affect organs• Thrombotic occlusion  gangrene
  4. 4. • Travellers/ inhabitants of endemic areas likely have septicemia but (-)cultures ?Typhus• Incubation period: 2 -23 days
  5. 5. Signs Mild/ asymptomatic Severe/ systemic: sudden fever, frontal headache, confusion & jaundice Eschar: dark crusty ulcer at the site of a bite Rickettsial rash: macular, papular, petechial or hemorrhagic
  6. 6. Laboratory• Hemolysis• Neutrophilia• Thrombocytopenia• Dec clotting• Hepatitis• Renal impairment
  7. 7. Epidemic typhus• R. prowazeki• Spread: human lice Pediculus humanus corporis• Brill Zinnser Disease• Rash: truncal, then peripheral• Incubation period: 5 – 21 days
  8. 8. Rocky Mountain Spotted Fever• R. rickettsii• Tick- borne• Most serious form• Incubation period – 1 week• Rash begins as macules on hands/feetSpreading, becoming petechial or hemorrhagic• More similar to typhus fever but the rash appears earlier and is more prominent.
  9. 9. Tick Typhus• R. conorri• Boutonneuse fever• Rash starts in axilla• Becoming purpuric as it spreads• Conjunctival suffusion• Jaundice, deranged clotting, meningoencephalitis, renal failure, cerebritis
  10. 10. Scrub typhus• Oriental tsutsugamushi• Most common in SE Asia• Signs:• Eschar from chigger bite• Hepatomegaly, cough, lymphadenopathy, tachyp nea, abdominal pain, constipation, edema, splenomegaly, vomiting , rash, petechiae, sudden deafness,
  11. 11. Scrub typhus• CXR: bilateral infiltration• Blood: LFT inc, thrombocytopenia, neutrophilia, lymphocytosis, +/- atypical lymphocytosis• Complications: pneumonia, pulmonary edema, meningitis, shock
  12. 12. Murine Endemic Typhus• R. typhi• Spread: fleas from rats (Xenopsylla cheopis)• Reservoir: Rat• to humans• Prevalent in warm coastal ports
  13. 13. Diagnosis• clinical history• physical exam• tests based on identification of the bacterial genus and species by PCR testing of skin biopsy of skin rash, skin lesions/blood samples• immunohistological staining that identifies the bacteria within infected tissue (skin tissue, usually)• Dx late or after the disease has been treated with antibiotics, when significant titers of antirickettsial antibodies are detected by immunological techniques.
  14. 14. Diagnosis• CBC: show anemia and low platelets• High level of typhus antibodies• Low level of albumin• Low sodium level• Mild kidney failure• Mildly high liver enzymes
  15. 15. ISOLATION• Blood is inoculated in guinea pigs/mice.• Observed on 3rd – 4th week.• Animal responds to different rickettsial species can vary• Symptoms:• Rise in temperature – all species.• Scrotal inflammation,swelling,necrosis – R.typhi, R.conori, R.akari ( except R.prowazekii)
  16. 16. Serology• Reliable test to confirm rickettsial diseases• Antibody detection by Weil-felix test• Antigen detection by IFA
  17. 17. WEIL-FELIX TEST• Heterophile agglutination test using• non motile proteus strains (OX 19, OX 2, OX K)• to find rickettsial antibodies in patient’s serum.• Procedure:• Serum is diluted in three separate series of tubes followed by the addition of equal amount of OX19,OX2,OXK in 3 separate series of tubes.• Incubation at 370C for overnight.• Observe for agglutination
  18. 18. WEIL-FELIX TEST• Strong Agglutination with OX 19 – means epidemic & endemic typhus.• Strong agglutination with OX 19 & OX 2 –• means Spotted fever• Strong agglutination with OX K – Scrub typhus• (Scrub typhus by Orientia tsutsugamushi• (one of the rickettsial disease)
  19. 19. PROPHYLAXIS• Vector control• Live vaccine & killed vaccine are available but not much effective
  20. 20. Treatment• Doxycycline 100mg/ 12hrs PO/IV for 7 days or48 hours after temp is normal• Chloramphenicol 500mg/ 6 hours PO for 10-14 days• Azithromycin 500 mg 1 dose for tick & Scrub typhus
  21. 21. http://crisbertcualteros.page.tl

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