Rickettsiae Clinical Microbiology Review 218
GENUS PATHOGENICITY LABORATORY DIAGNOSIS OTHER
Rickettsia
Coxiella
Ehrlichia
Obligate intracellular parasite. Transmitted by
ticks, mites, lice, fleas. Rocky Mountain spot-
ted fever is most common rickettsial infection
in U.S. Caused by R. rickettsii. BSL-3 biohazard.
Obligate intracellular parasite. Zoonotic
disease. Found in cattle, sheep, goats. Highly
contagious. BSL-3 biohazard. Reportable
disease. Potential bioterrorism agent.
Obligate intracellular parasite. Infects WBCs.
Transmitted by ticks. Disease similar to Rocky
Mountain spotted fever.
Rocky Mountain spotted fever,
rickettsial pox, epidemic typhus,
murine typhus, scrub typhus
Q fever
Ehrlichiosis
Don’t grow on artificial media.
Grow in lice, ticks, tissue culture,
eggs. Usually Dx by serology.
Immunohistologic & molecular
methods available.
Grows in cell culture. Usual Dx by
serology. Immunohistologic &
molecular methods available.
Morulae (clusters of organisms
that resemble blackberry) in
WBCs. Usual Dx by serology.
