Rickettsia Flashcards
Rickettsia ricketssia - Disease, Vector
Rocky Mountain Spotter Fever
Tick
This disease also called American Typhus in Europe
Rickettsia Typhi Disease, Vector
Endemic Typhus, Flea
Rickettsia Prowazeki - Disease, Vector
Endemic Typhus, Louse
Orientia tsutsugamushi - Disease, Vector
Scrub typhus, Chigger(mite)
Ehrlichia Chaffeensis - Diease, vector
Enrlichiosis, Tick
Anaplasma Pahgocytophilum
Anaplasmosis, TIck
Gram Stain, Serotype, virulence factor of Ricketssia
Gram Negative (PG and LPS), Obligate intracellular, Serotype surface proteins OmpA and OmpB Invade vascular endothelial cells by phagocytosis - escape phagosome. Obtain nutrients from the cytoplasm
Ehrlichia and Anaplasma - biology
membrane-bound vacuoles. No PG or LPS. Do not invade endothelial cells.
E invades monocytic leukocytes and Anaplasma invade PMN
Life cycle of RIckettsia
- Attachement and entry by induced phagocytosis
- Escape from phagosome, then do binary fission
- use host actin to invade other cells
- Heavily affected cells -
Necrosis, Or,
Immune clearance
Where is Rocky Mountain found?
South East America
Pathogenesis of Rickettsia - severe
Vascular damage –> leakage –> shock and peripheral edema
Pathogenesis continued
Loss of plasma into tissue space, hypovolemia and hypoproteinemia –> reduced perfusion of organs –> organ failure
Components of Immune Response
Antibodies form but are not protective
CD8+ T cells - destroy infected cells INF-G, TNF-A - activate endothelial cells to kill organisms
Diagnosis
Antibodies canbe used for diagnosis, cross reacting with antibodies to proteus vulgaris was basis for older weil felix reaction *not high yield
Who are more prone to RMSF?
Blacks and elderly with G6PD deficiency
When are you likely to get RMSF?
Summer time
How long does a tick have to feed? Incubation time?
6-10 hours
Incubation time - 10 days
Symptoms of RMSF?
Fever, Myalgia, Headache
3 days later - rash on hands feet, often on palm - centripetal direction
Can be maculopapular erythema –> petechiae –>necrosis and gangrene
Treatment?
Doxycyline
Epidemic Typhus
Can recrudesce
Scrub Typhi
Not in US. ESCHAR SCAB !! classic sign
Enrlichiosis and Anaplasmosis
Diagnosis
Similar to RMSF in incubation time, tick borne, summer, doxycline, symptoms. Except less common rash and no vasculitis
Leukopenia and thrombocytopenia more common
Serology - Indirect immunoflurescence, PCR or Blood smear for round inclusions in monocytes (E) and neutrophils (A)
