Rickettsia and Chlamydia
Zoonotic tetrad is in: (DNB June 2011)
a. Zoonotic tetrad is a feature of Scrub typhus.
b. It is caused by Orientia tsutsugamushi and transmitted by chiggers of mites.
c. Four factors are essential for establishment of a microfocus of infection: coexistence and intimate relationship of O.tsutsugamushi, chiggers, rats and secondary or transitional form of vegetation called zoonotic tetrad.