Cestodes | Cestodes
NCBISkiptomaincontentSkiptonavigationResourcesHowToAboutNCBIAccesskeysMyNCBISignintoNCBISignOutNCBIBookshelf.AserviceoftheNationalLibraryofMedicine,NationalInstitutesofHealth.BaronS,editor.MedicalMicrobiology.4thedition.Galveston(TX):UniversityofTexasMedicalBranchatGalveston;1996.MedicalMicrobiology.4thedition.ShowdetailsBaronS,editor.Galveston(TX):UniversityofTexasMedicalBranchatGalveston;1996.ContentsSearchtermChapter89CestodesDonaldHeyneman.GeneralConceptsClinicalManifestationsAdultTapeworms:Adultwormsarefoundinthesmallintestine;theseinfectionsareusuallywelltoleratedorasymptomatic,butmaycauseabdominaldistress,dyspepsia,anorexia(orincreasedappetite),nausea,localizedpain,anddiarrhea.LarvalTapeworms:Larvaelocateinextraintestinaltissuesandproducesystemicinfectionswithclinicaleffectsrelatedtothesize,number,andlocationofcysts.Taeniasoliumcysticercosis(infectionwiththecysticercuslarvalstage)isoftenasymptomaticandchronic;neurocysticercosis,ophthalmiccysticercosis,andsubcutaneousandmuscularcysticercosisare,however,frequentlyreported.Echinococcusgranulosushydatidlarvaemayformmassivecystsinliver,lungs,andotherorgans,includinglongbonesandthecentralnervoussystem.StructureAdults,whichmaturesexuallyinthedefinitiveorfinalhost,areribbon-shaped,multisegmented,hermaphroditicflatworms;eachsegmenthasacompletemaleandfemalereproductivesystem.Ananteriorholdfastorgan(thescolex)isfollowedbyagerminativeportion(“neck”)andsegmentsatsuccessivelylaterstagesofdevelopment.Larvaeencystinvarioustissuesoftheintermediatehost;larvalcystscontainoneormanyscolecesoffutureadultworms.MultiplicationandLifeCycleThetapeworm'slifecycleinvolvesadefinitiveandoneormoreintermediatehosts(exceptfortheone-hostcycleofHymenolepisnana).Eachtypeofcyclehasspecializedlarvalforms(cysticercus,cysticercoid;coenurus,hydatid;coracidium,procercoid,plerocercoid).PathogenesisPathologyduetoadultwormsresultsfromthephysicalpresenceandactivityofthelargeworms(Taeniaspecies),occasionalerosiveaction(causinglocalinflammation)by