Rickettsia Flashcards
(26 cards)
What type of organisms are Rickettsia?
-obligate intracellular bacteria
How are Rickesia Transmitted?
- Arthropods - ticks, mites, lice, fleas. Except coxiella brunetti
What are all the organisms in the Rickettsia family that we care about?
- R. Ricketssii, R. akari, R. tsutsugamushi, R. prowazekii, R. typhi, E. chaffeensis & E. ewingii, C. burnetti
What is the pathogenesis of Rickettsia organism?
-Enter through bite/abrasion –> endothelial cells, degrade phagosome by Phospholipase A, and replication in endothelial cells weakening vasculature (rash and hypovolemia).
What disease does R. rickettsii lead to?
What is the organism that transmits it?
- Rocky Mountain Spotted Fever (SE US)
- Dog Tick - more confirmed causes in the summer
What is the classic presentation of the rash with rocky mountain spotted fever (R. Ricketsii)
- fever chills headache, myalgia - 2 days later rash begins on hands and feet and spreads inwards to trunk. initially macular than petechial.
What is a diagnostic test for Rocky mountain spotted fever?
- Weil-Felix (non-specific) and symptom presentation
What Rickettsialpox caused by?
Where is it most frequently found?
- Rickettsia akari
- in Cities (NYC, Boston, Philly, Pittsburgh, Cleveland)
What is the vector for Rickettsia akari?
Presentation?
- mouse, mite
- Initial red papule, flu-like illness w/ profuse sweating, photophobia; later rash on palms and soles
What is the major disease associated with R. prowazekii?
What is prowazekii transmitted by?
- Epidemic Typhus
- human body louse (flying squirrel reservoirs)
What is the classic rash progression in Epidemic Typhus?
What is Recurrent Epidemic Typhus that can happen decades later?
- Fever chills, headache, myalgia; later maculopapular rash on trunk that spreads to extremities
- Brill Zinsser disease - milder
What is diagnostically significant about epidemic typhus?
- Positive Weil-Felix test and symptoms
What is Endemic Typhus cause by?
What is it transmitted by?
R. typhi - symptoms are not that specific - tough to test on (fever, chills, headache, myalgia)
- rat flea
What causes Scrub Typhus?
Where are they found?
- Orientia tsutsugamushi
- Asia, Australia, and pacific islands
What transmits Scrub Typhus?
- Chiggers (mites are reservoir)
What is Ehrlichiosis an infection of?
Transmitted by?
Presentation?
- WBC (monocytes and granulocytes)
- Ticks
- HME, HGE, and HGA the same
What does E. chaffeensis infect?
What does E. ewingii infect?
- monocytes –> human monocytic ehrlichiosis (HME)
- Granulocytes–>hyman granulocytic ehrlichiosis (HGE) - farmers, cowboys, butchers
What needs to occur with anaplasma phagocytophilum?
- coinfection with lyme disease
Which has a higher rate of mortality and hospitalization in HME and HGE?
- Mortality: HGE> HME
- Hospitalizations: HME > HGE **
How does Ehrlichiosis protect against degradation ?
- does not breakout of phagosome, inhibits fusion with lysosome and replicates within phagosome
What 2 organisms contains morula?
Ehrlichia or Anaplasma in WBC vesicle
What is Q fever caused by?
Where does the bacteria live in?
- Coxiella burnetii
- inside acidic lysosomes - extremely stable
How is it transmitted:
What profession is most at risk?
Inhalation of bacteria from goats, sheep, cattle, and cats
- Vets the number one risk factor
What is a more unlikely path of transmission?
What differentiates this from Erchilosis?
- ingestion of unpasteurized milk products
- No morula**
