rickettsial disease

Question 1

Which organisms belong to rickettsial disease (gram - bacteria)? ROEAC

Answer 1

1. rickettsia (endothelial cells)
2. orientia (endothelial cells)
3. ehrlichia (macrophage**/PMNs)
4. anaplasma (PMN)
5. coxiella (macrophage)

**coxiella is the only one that belongs to a different order (legionella), all of the others belong to the rickettsial order

** the treatment for all of these listed here and throughout this chapter is DOXYCYCLINE

Question 2

spotted fever and typhus group

Answer 2

caused by: rickettsia (mainly American dog tick)
fever, myalgia, skin manifestations
DDX includes: Maculatum disease (American tick bite fever) seen in central/southeast US and S America, African tick bite fever seen in sub-saharan Africa, and Rickettsialpox seen in urban areas of America caused by mite bite.

*most spotted fevers will present with eschar at inoculation site, excluding RMSF and non-scrub typhus group

Question 3

scrub typhus

Answer 3

caused by: orientia tsutsugamushi, specifically in trombiculid mites
fever, LAD, headache, skin manifestations starting with ESCHAR
found in Asia and Australia

Question 4

human ehrlichioses

Answer 4

caused by: ehrlichia chaffeensis (macrophage) and Ewingii (PMN), specifically white tailed deer and lone star ticks (aka amblyomma americanuum)
skin manifestations vary greatly
found in the USA
***E. Ewingii has no skin findings

Question 5

human granulocytotrophic anaplasmosis

Answer 5

caused by: anaplasma phagocytophilum, specifically Ixodes scapularis and pacificus tick aka blacklegged tick (**same tick as in Lyme & Babesiosis disease)
peripheral neuropathy, skin manifestations (RARE)
**a/w Sweet’s

main points: ixodes scap, sweet’s, peripheral neuropathy

Question 6

Q fever

Answer 6

caused by: coxiella burnetti
Transmitted via aerosols of infected sheep and cattle
fever, atypical pneumonia, in chronic form –> culture negative ENDOCARDITIS, skin manifestations (RARE)

Question 7

+ more including typhus group (ECE) and spotted fever group (RMR)

Answer 7

Endemic/murine typhus - r. typhi transmitted by xenopsylla cheopis, no eschar

Cat flea typhus - r. felis transmitted by ctenocephalides felis, no eschar

RMSF - r. rickettsii transmitted by dermacentor variables, dermacentor andersoni, no eschar, most common

Meditteranean spotted fever aka boutonneuse fever - r. conorii transmitted by rhipicephalus sanguine, +eschar, favors legs

Rickettsial pox - r akari transmitted by liponyssoides sanguineus, self limited, will resolve in 3 weeks