<prompt> Scrub typhus is cause byRickettsia tsutsugamushiR. prowazekiiR. rickettsiiR. akari  <response>: Ans. a Rickettsia tsutsugamushi Ref Ananthanarayan, Microbiology, 8thfp. 408, 410; Park 20th263 Scrub typhus is caused by R. tsusugamushi. The vector is trombiculide mite. The microbes are transmitted transovarially in mites.SCRUB TYPHUS CHIGGER-BORNE TYPHUS Causative agent is R. tsutsugamushi. Important reservoir is trombiculoid mite. The nymphal and the adult stages of mite are free living in the soil. They do not feed on vertebrate host. Larva chigger feeds on vertebral host and picks up the rickettsiae. Infection is maintained in nature transovarially from one generation of mite to next. Larval stage serves both as reservoir, through ovarian transmission, and as a vector for infecting humans and rodents. Tertacycline is the only drug of choice. Sulfonamides should not be given.DiseaseCausative agentsVectorReservoirWF reactionCommentsEpidemicR. prowazekiLouseHuman OX19 Red louse diseasetyphus Transmitted by Pediculosis corporis and capitis. Centrifugal rash 5 days after fever Reactivation leads to Brill-Zinsser diseaseEndemic Murine typhusR. typhi mooseriRat fleaRodent OX19 Tunica reaction Rash on 4th day of feverScrub typhusR. tsutsugamushiMite ChiggersRodentOXK Punched-out ulcers with eschar Erythematous rash on 5th day of fever Lymphadenopathy Zoonotic tetradIndian tick typhusR. conoriiTickRodent Dogs- Fever boutounneuse Tachenoir escharRMSFR. ricketssiTickRodent DogsOX19, 2 Most severe ricketssial disease Rash on wrist, palm and sole 3rd day of fever Indirect immunofluo-roscence .Rickettsial poxR. akariMiteMice- Most mild disease Eschar seenQ-feverCoxiella burnetti Cattle, sheep and goats- No rash or local reaction. No arthropod vector Vaccine availableTrench feverRochalimaea quintanaLouseHuman- Only rickettsia that can be culturedEherlichiosisE. senetsu, canlsTick bite-- No eschar rash Morules diagnostic. 