louseborn typhus is epidemic typhus caused by R.prowazekii whose distribution is worldwide,pediculis humanus corporis(human body louse) act as vector, incubation period is 5_15 days,disease stas with fever and chills, a characteristic rash appears on 4th or 5th day stas on trunk spreads over limbs except face,palm,soles..2nd week:patient become delirious and stuporous.recrudescent typhus(Brill zinsser disease)is by reactivation leading to recrudescence of epidemic typhus Ref:anantnarayan and paniker's microbiology 10th edition