(XII) Obligate Intracellular Pathogens (2) Rickettsia & Orientia spp

Question 1

Characterize (2) : Ricketsia spp.

Answer 1

(1) Obligate intracellular
(2) Poorly gram staining coccobacillus

Question 2

Describe the rash of Rickesttsia prowazekki

Answer 2

(1) Progresses from Central → Peripheral
(2) Spare hands, feet, and head

Question 3

Describe the progression of the rash of Rickettsia rickettsii

Answer 3

(1) Delayed onset (2-14 days)
(2) Starts on ankles/wrists → Moves central

Question 4

Name the disease that these Rickettsia & Orientia spp organisms cause, as well as the vectors that carries them

R. prowazekii: […], transmitted by […]
R. typhi: […], transmitted by […]

O. tsutsugamushi: […], transmitted by […]

R. rickettsii: […], transmitted by […]

Answer 4

Name the disease that these Rickettsia & Orientia spp organisms cause, as well as the vectors that carries them

R. prowazekii: epidemic typhus, transmitted by louse
R. typhi: endemic/murine typhus, transmitted by fleas, rats

O. tsutsugamushi: scrub typhus, transmitted by mite, rats

R. rickettsii: Rocky mountain spotted fever (RMSF), transmitted by tick

Question 5

Reactivation of R. prowazekii infection results in […] disease

Answer 5

Reactivation of R. prowazekii infection results in Brill-Zinsser disease

Question 6

Treatment for typhus/scrub typhus/RMSF?

[…]

Answer 6

Treatment for typhus/scrub typhus/RMSF?

Doxycycline

HH: “wheels for the….rickshaw. HAHAHHAHAHA”

Question 7

What is the clinical “triad” of Rickettsia and Orientia infections? (IMPT!!)

1. […]
2. […]
3. […]

Answer 7

What is the clinical “triad” of Rickettsia and Orientia infections? (IMPT!!)

1. Fever
2. Headache
3. Rash (+ Eschar)

Can be severe also, leading to SIRS and meningoencephalits

Question 8

Which 2 of the Rickettsia and Orientia spp are common in singapore?

[…]

Answer 8

Which 2 of the Rickettsia and Orientia spp are common in singapore?

R. typhi (murine typhus) & O. tsutsugamushi