HomeEditorialBoardReviewsContactUsSearchOrientiatsutsugamushi (ScrubTyphus)Authors:PhilippeParola,M.D,Ph.D., PrPhilippeBrouqui,M.D,Ph.D.,  GeorgeWatt,M.D.MonographTablesWhat'sNewReviewsHistoryMicrobiologyOrientiatsutsugamushi (formerlynamed Rickettsiatsutsugamushi)istheagentofscrubtyphus.Thisbacteriahadbeenclassifiedforalongtimeintheorder Rickettsiales asmeetingtheclassicdefinitionofrickettsiae:ashort(0.5X1.2to3.0microm)Gram-negativeobligateintracellularbacteriaretainingbasicfuchsinwhenstainedbythemethodofGimenez(25).However,intherecentyearstheadventofmoleculartaxonomicmethodsinphylogeneticstudies,particularly16SrRNAsequenceanalysis,hasenabledareclassificationofseveralbacterialspecies,includingtherickettsiae.Then,thepositionof R.tsutsugamushi hasbeenshowntobesufficientlydistincttojustifythecreationofanewgenus, Orientia (32). O.tsutsugamushi presentsalargenumberofserotypes.Themajorsurfaceproteinantigenisthe56-kDaproteinincludinggroup-specificandstrain-specificepitopes.However,severalmajorserotypes(Karp,Kato,Gilliam,KawasakiandBoryon)havebeenshowntopresentsufficientcross-reactivitywithantigenfromotherstrainstobeusedfortheserologicaldiagnostic. EpidemiologyScrubtyphus(synonyms:chigger-bornerickettsiosis,tsutsugamushidisease,ruraltyphus)isanacutefebrileruralzoonosisendemicintheAsia-PacificregionfromKoreatoPapuaNewGuineaandQueensland,Australia,andfromJapantoIndiaandAfghanistan.About1millioncaseshavebeenestimatedtooccureachyearand1billionpeoplemaybeexposed(27).Endemicareasrangefromtypicaltropicalsecondarygrowth(scrub)vegetationtotemperatezonesandeventheHimalayas.Althoughscrubtyphusisessentiallyanoccupationaldiseaseamongruralresidentsengagedinagriculturalorgatheringactivities,travelersorsoldiersinthefieldmaybeinfectedwhenenteringthebiotopeofthevectors(23, 39).Thediseaseistransmittedbythebitesofseveralspeciesoflarval-stageoftrombiculidmites(commonlycalled"chiggers"),whichareknownasbothreservoirsandvectorsofthedisease.Theybitehumansonanypartofthebodyandfeedfor2to10days.Clini