Medical Microbiology

562 10 Helminths

tachestothemucosaoftheuppersmallintestine,anddevelopsintoanadult

tapeworm,whichcanliveforyearsorevendecades.Abouttwotothree

monthsaftertheinfection,thefirstgravidsegmentsdetachfromthestrobila

andthenappearinfecesortheycanmigrateoutoftheintestinewithoutde-

fecation.Thesegmentsremainmotileforsometimeandfrequentlyleavethe

stools.

Pathogenesisandclinicalmanifestations.Insomeinfectedpersons,T.sagi-

natacausesmorphologicalchanges(villusdeformation,enterocyteprolifera-

tion,cellularmucosalinfiltration,etc.)andfunctionaldisturbances.Bloodeo-

sinophiliamayoccursometimes.Theinfectiontakesanasymptomaticcourse

inabout 25 %ofcases.Symptomsofinfectionincludenausea,vomiting,upper

abdominalpains,diarrheaorconstipationandincreasedordecreasedappe-

tite.Infectiondoesnotconferlevelsofimmunitysufficienttopreventrein-

fection.

Diagnosis.ATaeniainfectioniseasytodiagnoseifthe 1 .5– 2 cmlongand

0.7cmwidesegmentsareeliminatedinstool(Fig. 1 0.7c,d).Morphological

speciesdifferentiation(T.saginatavs.T.solium)isoftennotpossiblebased

onthegravidproglottids,butcanbedonebyDNA-analysis(PCR).T.saginata

eggsareshedirregularlyinstoolandcannotbedifferentiatedmorphologi-

callyfromT.soliumeggs(Fig. 1 0. 1 ,p. 54 4).UsinganELISA,coproantigensare

detectableinstoolfluidevenwhenneitherproglottidsnoreggsarebeing

excreted.

Therapyandprevention.Thedrugofchoiceisthehighlyeffectivepraziquan-

tel.Albendazole,mebendazole,andparomomycinarelessreliable.Themain

prophylacticmeasuresaresewagetreatmentandthedetectionofcysticercus

carriersatinspectionofslaughteranimals.Meatcontainingnumerouscysti-

cerci(“measlymeat”)hastobeconfiscated,butmeatwithsmallnumbersof

cysticercicanbeusedforhumanconsumptionafterdeep-freezingthatis

lethaltotheparasites.Individualprophylaxisconsistsofnoteatingbeef

thatisraworhasnotbeendeep-frozen.

Taeniasaginataasiatica

CausativeagentofAsiantaeniosis

ThisformofTaeniaoccursinthesmallintestineofhumansinEastandSoutheast

Asia(Korea,Taiwan,thePhilippines,Thailand,Indonesia,Malaysia).Geneticanalysis

hasrevealedaclosesubspecies-relationtoT.saginata(=T.saginataasiatica).The

twoformsdifferinanumberofmorphologicalfeatures;inaddition,thecysticerciof

T.saginataasiaticadevelopmainlyintheliversofpigs,butalsoinfectcattle,goats,

andmonkeyspecies.

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Kayser, Medical Microbiology © 2005 Thieme