1.
Typhus
The Rickettsial Disease

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.
Pathology
• Widespread vasculitis and endothelial
proliferation affect organs
• Thrombotic occlusion  gangrene

4.
• Travellers/ inhabitants of endemic areas likely have
septicemia but (-)cultures ?Typhus
• Incubation period: 2 -23 days

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.
Laboratory
• Hemolysis
• Neutrophilia
• Thrombocytopenia
• Dec clotting
• Hepatitis
• Renal impairment

7.
Epidemic typhus
• R. prowazeki
• Spread: human lice Pediculus humanus
• Brill Zinnser Disease
• Rash: truncal, then peripheral

8.
Rocky Mountain Spotted
Fever
• R. rickettsii
• Tick- borne
• Rash begins as macules on hands/feet
Spreading, becoming petechial or hemorrhagic

9.
Tick Typhus
• R. conorri
• Rash starts in axilla
• Becoming purpuric as it spreads
• Conjunctival suffusion
• Jaundice, deranged
clotting, meningoencephalitis, renal
failure, cerebritis

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.
Scrub typhus
• CXR: bilateral infiltration
• Blood: LFT
inc, thrombocytopenia, neutrophilia, lymphocytosis,
+/- atypical lymphocytosis
• Complications: pneumonia, pulmonary
edema, meningitis, shock

12.
Murine Endemic Typhus
• R. typhi
• Spread: fleas from rats to humans
• Prevalent in warm coastal ports

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.
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.
Treatment
• Doxycycline 100mg/ 12hrs PO/IV for 7 days or
48 hours after temp is normal
• Chloramphenicol 500mg/ 6 hours PO for 10-14 days
• Azithromycin 500 mg 1 dose for tick & Scrub typhus

16.
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