SalmonellaTyphiisaGram-negativebacteriumthatcausestyphoidfever,aseriousandsometimeslife-threateningillnessinhumans.Itistransmittedthroughcontaminatedfoodandwater,primarilyinareaswithpoorsanitation.Thebacteriuminvadestheintestinaltractandcanspreadtothebloodstream,leadingtosymptomssuchashighfever,weakness,stomachpain,headache,andlossofappetite.Withoutproperantibiotictreatment,typhoidfevercanbefatal.Vaccinesareavailabletohelppreventinfection,especiallyfortravelerstohigh-riskregions.SalmonellaTyphiiscloselyrelatedtootherSalmonellaspeciesbutisuniqueinitsabilitytoinfectonlyhumans.
