For 10 points, name this genus of intracellular gram-negative bacteria, which contains the causative agents of typhus.
One organism originally placed in this genus is now the only member of genus Orientia. One method of distinguishing between members of this genus is via cross-reactivity between the Proteus antigens OX19, OXK, and OX2; that is the Weil-Felix test. Like Chlamydia, this genus contains organisms that are obligate intracellular parasites that appear pleomorphic under Giemsa staining.  This genus contains the species felis, japonica, conorii, and akari, and it also contains the species most closely related genetically to the mitochondrion, called prowazekii. One member of this genus is carried by Dermacentor variabilis and causes a maculopapular centripetally-spreading rash. Besides containing the causative agent of (*) Rocky Mountain Spotted Fever, this genus also contains the causative agent of a disease transmitted by lice that killed many soldiers during World War II. For 10 points, name this genus of intracellular gram-negative bacteria, which contains the causative agents of typhus.
One organism originally placed in this genus is now the only member of genus Orientia.
Rickettsia