Rickettsia

Question 1

etio

Answer 1

Rickettsiae.Gram-negative bacteria.Coccobacilli/short bacilli;obligate intracellular

Question 2

Transmission

Answer 2

arthropods;tick,mite, flea,louse;mammalian reservoirs;humans are
incidental hosts.

Question 3

Manifesation

Answer 3

Tâche noire (black spot or stain).
Coin-like lesion with central eschar and a red halo at the site of the vector-bleeding bite site.

EXANTHEM Macules–papules. Exception: Rick- ettsialpox with papules–vesicles.

LATERFINDINGSVARYINGWITHPATHOGEN May become hemorrhagic with vasculitis.

Question 4

histo

Answer 4

Vasculitis, necrosis, theombosis

Question 5

Order of case fatality rate from highest to lowest

Answer 5

Order of decreasing case fatality rate:

R.rickettsii RockyMountainspotted ever (RMSF)];

R. prowazekii (epidemic louse- borne typhus);

Orientia tsutsugamushi (scrub typhus);

R. conorii (Mediterranean spotted
ever);

R. typhi (endemic murine typhus);

Question 6

Treatment

Answer 6

Doxycyclin drug of choice,100mgBID orally.

Alternates: Ciprofloxacin or chloramphenicol.