Rickettsia
Rickettsia felis
Rickettsia prowazekii
Rickettsia rickettsii
Rickettsia typhi
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Bacteria of the genus
Rickettsia are carried as
parasites by many
ticks,
fleas, and
lice, and cause
diseases such as
typhus, rickettsialpox,
Brill-Zinsser disease,
Boutonneuse fever, and
Rocky Mountain spotted fever in human beings. Like
viruses, they grow only in living tissue. Judging by the scientific literature, research into the
genetics of rickettsiae has been less intense than into that of viruses and other bacteria. Diseases caused by some other bacteria, such as
Coxiella burnetii, the cause of
Q fever, are also considered rickettsial diseases, though the organisms are no longer considered particularly close relatives.
The genus
Rickettsia is named after Howard Taylor Ricketts (
1871–
1910). Despite the similar name,
Rickettsia bacteria do not cause
rickets. The disease of rickets takes its name from the
Greek word for
spine,
rhakhis, and is a vitamin deficiency disease, not an infectious disease.
