LIFECYCLE[2]ThelifecycleofT.soliumisrepresentedgraphicallybelow.Itconsistsofsixmainsteps:FigurecourtesyoftheCDC'sDivisionofParasiticDiseases.[C]STEP1.Infectedhumans(definitivehost)excretetheeggsorgravidproglottidsintheirfeces,passingtheparasitefromthegastrointestinaltractontonearbyvegetation.Ineggorgravidproglottidform,T.soliumisabletoremainviableanywherefromdaystomonths.T.soliumcanbediagnosedatthispointinthelifecycle.Note:Autoinfectioncanalsooccuratthispointinthelife-cycleviafecal-oralcontamination.Inthiscase,eggsorgravidproglottidsre-enterthebodythroughthemouthandoftentraveltothecentralnervoussystem(CNS),themusclesortheeye,wheretheydevelopintocysticerci.Thepresenceofcysticerciintheselocationsleadstothepathogenesisofcysticercosis(neurocysticercosisintheCNS).[4,5]STEP2.Pigs(intermediatehost)acquireinfectionbyeatinganddigestingtheeggsorgravidproglottidsalongwiththeparasitizedvegetation.STEP3.Theeggsorgravidproglottidsmigratetothepig'sintestineandasoncospheres,breakthroughtheintestinalwall.Then,viathecirculatorysystem,theyembedthemselvesinthemusclesofthepiganddevelopintocysticerci(theinfectiveformofT.solium).Cysticercihavetheabilitytopersistinthemuscleformanyyears.STEP4.Humansacquiretheinfectionbyeatingtheundercookedorrawfleshofaninfectedanimal.STEP5,6.Cystercercimigratetothesmallintestineofthehumanhostanddevelopintotheiradulttapewormformnormallywithintwomonths.Byattachingtotheintestinalwallwiththeirscolices(hookedstructures),theseadulttapewormsmaypersistforlongperiodsoftime,evenyears.