人體寄生蟲學(xué)：02 臨床八年制蛔蟲蟯蟲、鉤蟲

蠕蟲（helminths）是一種軟體動(dòng)物，借助肌內(nèi)的伸縮而蠕動(dòng)的多細(xì)胞動(dòng)物其形態(tài)結(jié)構(gòu)上的共同點(diǎn)是身體由上皮和肌內(nèi)構(gòu)成的皮膚肌內(nèi)囊包囊，蟲體兩側(cè)對(duì)稱，器官分化PhylumNemathelminthes：ClassSecernentea(分腸綱）ClassAdenophorea（有腺綱）PhylumPlatyhelminthes:ClassTrematoda

(fluke)ClassCestoda(tapeworm)寄生在人體的蠕蟲引起的病，成為蠕蟲病Medicalhelminthology線蟲綱

1999年世界衛(wèi)生組織指出：“在熱帶和亞熱帶地區(qū)，土源性線蟲病和血吸蟲病帶來(lái)的損失占全部疾病負(fù)擔(dān)的40％以上。發(fā)病多見(jiàn)于兒童，常引起營(yíng)養(yǎng)不良、貧血、生長(zhǎng)遲緩、智力受損，極易患其它的感染等”。NematodesMorphology

themostwormlike,roundwormsalightcream-whitecolor,butthefemaleofthesmallerformsmayappeardarkerwhenfilledwithdark-coloredeggcontainabodycavity,orpseudocelom(nutrients)

Structure(bodywall)

cuticulalayer(角皮層)

subcuticularlayer(皮下層)

muscularlayer(縱肌層)（三）消化系統(tǒng)（四）生殖系統(tǒng)ACBA：meromyarian(少肌型)

例如：鉤蟲

B：polymyarian(多肌型）

例如：蛔蟲

C：holomyarian(細(xì)肌型)

例如：鞭蟲蟲卵幼蟲成蟲線蟲幼蟲發(fā)育中最顯著的特征是蛻皮therearethreemodesbywhichinfectionsistransmittedIngestion(mostoften)SkinpenetrationInsectbite

Lifecycle

蟲卵形態(tài)成蟲形態(tài)thelifecyclescoulddividedintodirectandindirecttypesbasisofwithoutintermediatehostorwithintermediatehost不需要中間宿主型：蟲卵或幼蟲不需離開人體而立即具有感染力蟲卵需在外界發(fā)育成感染期蟲卵具有感染力蟲卵需在外界發(fā)育為感染期幼蟲具有感染力雌蟲產(chǎn)出幼蟲經(jīng)血流到肌內(nèi)形成包囊而具感染力需要中間宿主型：幼蟲需在中間宿主或媒介體內(nèi)發(fā)育為感染期幼蟲后由媒介叮人吸血時(shí)感染人體Microscopicexaminationoffecalspecimens糞便檢查DirectWetSmearwithsaline(直接涂片法)SedimentationConcentration(飽和鹽水浮聚法)Culture(培養(yǎng)法)：定量檢查

theCellulosetapepreparation(透明膠紙粘貼法、棉簽拭子法)PCR:PCR檢測(cè),一個(gè)蟲卵即可診斷Diagnosis&Prevention:Sincethisinfectionissocommonandtransmissionissoeasy,preventionismarginal.Improvedpersonalandgrouphygienecombinedwithgrouptherapycanbehelpful.Undermostcircumstances,totalpreventionisneitherrealisticnorpossible糞管,注意環(huán)境衛(wèi)生、家庭衛(wèi)生、個(gè)人衛(wèi)生及防止相互感染治療病人和帶蟲者

Ascarislumbricoides(似蚓蛔線蟲),簡(jiǎn)稱蛔蟲

Itisthelargestnematodeparasiteinthehumanintestine.

成蟲寄生在小腸，引起蛔蟲病(ascariasis)，有時(shí)可以進(jìn)入膽道等臟器引起嚴(yán)重并發(fā)癥。MorphologyAdult:large&pinkworms

Ascarislumbricoidesfemaleworm:20to35cmmaleworm:30cm蟲卵egg

受精卵fertilizedegg

未受精卵unfertilizedeggBBBA受精膜殼質(zhì)層蛔甙層Lifecycleunderfavorablecondihtionstheeggdevelopedtoinfectivestage

(蟲卵在外界發(fā)育)underanextraordinarymigrationthroughthebody(幼蟲在體內(nèi)移行)成蟲在小腸寄生成蟲蟲卵含蚴卵感染性卵

產(chǎn)卵5-10days7days小腸壁V門V右心肺肺部微血管肺泡咽食道幼蟲移行途徑(60-75days)移行途徑：Maturefemalewormshavebeenestimatedtoproducedailyanaverageof240000eggsAfterinfectiveeggsareswallowed,thelarvaehatchinvadetheintestinalmucosa,andcarriedviatheprotal,thensystemiccirculationstothelungsThelarvaematurefurtherinthelungs(10-14days)thenpenetratethealveolarwalls.Duringthisstage,pulmonarysymptomscanoccurwithcough,andeosinophilicpneumonitis(Loefflersyndrome)肺部癥狀:X-RAY肺部浸潤(rùn)影；血嗜酸性細(xì)胞增多；異位侵入PathogensisHelminthinfectionsinduceTh2responsesthatarecharacterizedbyeosinophilia.Antiparasiteantibodies(oftheIgEisotype)alsowereinduced.Larvae

stageAdultstageThelarvaeascendthebronchialtreetothethroatandareswallowed.WhentheyreachthesmallintestineanddevelopintoadultwormTheadultwormliveinthelumenofthesmallintestineAfemalewormmayproduceeggs,whicharepassedwiththefecesInyoungchildren,alargebolusofentangledwormsinthesmallbowelcauseabdominalpainandintestinalobstruction營(yíng)養(yǎng)不良

過(guò)敏反應(yīng)

常見(jiàn)并發(fā)癥(異位)MostpatientsremainasymptomaticAdultwormsrecoveredfromchildaftertreatmentwithmebendazole.Childwithdistendedabdomen(bolusofA.lumbricoidesadultsinsmallintestines)obstructadiverticulumobstructingofintrahepaticandextrahepaticbileductsBiliarytree:branchesofbileductintheliver.Theliverproducesbilewhichissecretedviatheductstotheintestinetoaidindigestionoffats.Pancreatitis:inflammationofthepancreasAdultascaris(arrow)inappendix.AstudybyCooperetal(2003)inEcuadorsuggestthatinfectionwithintestinalhelminths,particularlyascaris,protectsagainstthedevelopmentofseverinflammatorydiarrheainchildren.Thepossibleprotectivemechanismmaybetheproductionofantimicrobialsubstancesbythewormsortheincreaseinmucosalresistancethroughmodulationofthemucosalimmuneresponse.InfectionwithintestinalhelminthshasalsobeenusedasanexperimentalremedyforinflammatoryboweldiseaseSomeadditional?!

Laboratorydiagnosis---stoolexamination1.directwetsmear直接涂片法,2.沉淀法

3.sedimentofconcetrated飽和鹽水浮聚法

4.驅(qū)蟲治療性診斷Epidemiology世界性分布Ascariasisaffectsmoreoftheworld’spopulationthananyotherparasiticdisease—perhapsasmanyas1.3billionpersons.Thepercapitawormburdenmayreachhundreds,orevenathousandormoreinasingleindividual.Intheworldwideifplaceheadtotailthewormwouldencircletheworld50times!

感染率高的原因:產(chǎn)卵量大

生活史簡(jiǎn)單

蟲卵抵抗力強(qiáng)生產(chǎn)生活方式

Treatment，Preventionandcontrolalbendazole：200mg(兒童)

400mg(成人)sideeffectareminimalmebendazole：100mgbid×3daysImprovedpersonalhygieneamongpeoplewhohandlefoodisanimportantaspectofcontrol

EnterobiusvermicularisEnterobiusvermicularis,thehumanpinworm成蟲寄生在盲腸、闌尾、直腸等處引起蟯蟲病(enterobiasis)。

MorphologyShortandwhitefusiformwormThemaleis2to5mmlongand0.1to0.2mmthickThefemaleis8to13mmlongand0.3to0.5mmthick感染期卵成蟲卵

幼蟲Lifecycletheeggmaysurviveforsomedaysindrydustairborneeggsmayinfectpersonatsomedistanceatypeofautoinfectiondescribedas“retrofection”Pathogensis是常見(jiàn)的小兒科疾病pinwormsortheireggshaveoccasionallybeenreportedfromotherectopicsites,suchasliverandlung

蟯蟲性闌尾炎

蟯蟲性泌尿生殖系統(tǒng)炎癥Diagnosis發(fā)現(xiàn)蟲卵或成蟲即可診斷從糞便中檢出蟲卵率低于5-15%？透明膠紙粘貼法、棉簽拭子法

Crosssectionofadultinappendix.crosssectionsofEnterobiusvermicularisinappendix

Epidemiology蟯蟲病是世界性分布的常見(jiàn)寄生蟲病傳播方式

1.經(jīng)口感染直接或間接

2.吸入感染

3.逆行感染retrofectionPinwormisbyalloddsthemostcommonhelminthparasiteofthosetemperateregionswheresanitationmeasuresarerelativelyrigorousasmuchas10%ofthepediatricpopulationmaybeinfectedinthesearealessattentionispaidtopinworminthetropicalareas,probablybecauseoftherelativeprevalenceofmoreimportantparasites蟯蟲病分布廣泛的原因

生活史簡(jiǎn)單

蟲卵抵抗力強(qiáng)，一般濃度消毒液不能殺死蟲卵

衛(wèi)生習(xí)慣不良Healtheducationonpersonalandcommunityhygieneandgroupchemotherapyconstitutethecontrolmeasure

(普治共治，集體治療)注意環(huán)境衛(wèi)生、家庭衛(wèi)生、個(gè)人衛(wèi)生及防止相互感染。治療病人albendazole：200mg(兒童)400mg(成人)mebendazole：100mgbid×3days

Topreventre-infection,treatthewholefamily.Treatment，PreventionandcontrolA3-year-oldgirlwasbroughttotheemergencydepartmentofageneralhospitalfollowinga3-weekhistoryofnausea,poorappetite,andabdominalpain.Shehadnothadanybowelmovementsforthelast2days.VS:T37°C,P110/min,R20/minBP102/54mmHgPE:Youngchildinmoderatedistressduetoabdominalpain.AbdomenwasdistendedandmildlytenderHematocrit:38%WBC4500/lDifferential:62%PMNs,23%lymphs,12%eosinophilesSerumchemistries;NormalToday’sCaseImagingX-raysofherabdomenwereconsistentwithintestinalobstructionHookwormHookworminfectioniswidelydistributedintropical&subtropical,wheretherearefavorableenvironmentalfactorforhookwormspreading,includingwarm,highrainfall,soilpollutionbyhumandefectionorfertilizationwithhumanfecesandpersonwalkingwithbarefeet.Hookworminfectionissecondonlytoascariasisasthemostcommonhelminthicinfection.HookworminfectionhasalmosteradicatedfromEuropeandUnitedStates.Ancylostomaduodenale(十二指腸鉤蟲)-----------thesmallintestineNecatoramericanus(美洲板口線蟲)--------------thesmallintestineAncylostomacerlanicum(錫蘭鉤口線蟲)-rarelyinfectshumanbeingsAncylostomacaninum(犬鉤口線蟲)-------rarelyinfectshumanbeingsAncylostomabraziliense巴西鉤口線蟲----creepingerupting,幼蟲可感染人，引起幼蟲移行癥

鉤蟲是一類口囊發(fā)達(dá)的線蟲，并在口囊內(nèi)有銳利的切器，可損傷腸粘膜，吸食血液和組織液，使患者長(zhǎng)期慢性失血，造成嚴(yán)重危害。鉤蟲寄生小腸引起鉤蟲Hookworminfectioniscontractedmainlybypenetrationoftheskinororalmucosabythefilariformlarvae(infectivestage)ofhookworm.Thus,barefootfarmersandchildrenwalkingoncontaminatedsoiloreatingcontaminatedvegetablesmaybecomeinfected.AdultsofA.duodenale

AdultsofN.americanusDifferencesbetweentwohookwormsMorphologyThemalewormisabout7to11mminlength&about0.4mmthickThefemaleislarger,9to13mmlongando.6mmthickFemaleshookworm:9-13mmlongwithegg-filleduterusMalehookworms:7-11mmlongPosteriorendformsacopulatorybursaAdult:theadultarecylindricalwiththeheadbentsharplybackwards,givingthemahookedappearance.Themouthofhookwormwerewelldeveloped,withapairofteethorapairofcuttingplate._____________________________________________________A.duodenaleN.americanus______________________________________________________Sizelargersmaller______________________________________________________Shapesinglecurve,lookslikeCdoublecurves,lookslikeS______________________________________________________Mouth2pairsofventralteeth1peirofventralcuttingplates____________________________________________________________CopulatorycircleinshapeovalinshapeBursa(2-3)(2-2)____________________________________________________________Copulatory1pairwithseparate1pairofwhichunitetoformspiculeendingsaterminalhooklet_______________________________________________________caudalspinepresentno_______________________________________________________vulvapositionpost-equatorialpre-equatorial_______________________________________________________TheMorphologicalDifferencesbetweenTwospeciesofHookwormsEgg(蟲卵)Eggoftwospeciesarenearlyindistinguishable.Theyareovoidwithathintransparentshelland,measure60mX40m,aclearspacethatseparatestheshellfromtheyolkcells.Thenumberofyolkcellsineggfoundinthestoolvariesfromtwotoeight.Larvaarhabditiformlarva(桿狀蚴):275X16m,thenewlyhatchedlarvafeedactivelyuponbacteriaandorganicdebris,growrapidlytoasizeof500to700min5daysafilariformlarva(絲狀蚴):slender,nonfeedingtheactivefilarformlarvafrequenttheupperhalf-inchofsoilandprojectfromthesurface-------infectivestage

頭端 扁平，中間微凹圓形，無(wú)凹陷

咽管矛不明顯 明顯

鞘膜橫紋不明顯 明顯

尾端 逐漸變細(xì) 驟然變尖 Ad絲狀蚴 Na絲狀蚴 十二指腸鉤蟲和美洲鉤蟲的分布/致病力/藥敏性各異Theysurvivebestinshadedlocalities,suchaslightsandyoralluvialsoilorloamcoveredbyvegetation,theyareprotectedfromdryorexcessivewetnessat0oClarvasurvivelessthan2wksat11oClessthan24hrsat45oClessthan1hrLifecycleHumansalmostexclusivelyarehostsforbothhookworm,whiledogsalsoarecommonhostforN.americanus.Wheneggsareexpelledwithfeces,underoptimalconditions(temperatureof23-33oC,shade,andsandysoilrichinorganicmaterial),arhabditiform-larvamaturesin1-2days&hatchesfromthethinshelledegg,feedsonbacteria&organicmaterialinthesoil.Aftertwomolts,itbecomesanon-feeding,infective,filariformlarva.

Finalhost:manInfectiveStage:Larva3orfilariformlarvaInfectiveRoute:byskin…Food:bloodandtissuefluidSiteofinhabitation:smallintestineLifespan:Ad15years,Na3-7yearsBlood-lungmigration:skin,cavumvena,rightheart,lungs成蟲卵桿狀蚴絲狀蚴（感染期）

經(jīng)皮膚粘膜移行途徑皮膚小血管右心肺肺部微血管肺泡

食道咽小氣管Ad

保蟲宿主：豬、獅、虎、狗、猴Na

轉(zhuǎn)續(xù)宿主：猩猩、猴、犀牛等

成蟲寄生部位和攝食

Adultworminsmallintestine產(chǎn)卵量Ovaproduct

A.duodenaleproduces10000to

30000eggsperday

N.americanusproduces5000to10000eggsperday絲狀蚴具有向上性、向濕性、向溫性

character

of

filariformlarva:strongthigmotaxis,

moisture,thermotaxis(1-2cm)Penetrationskinororalmucosa(A.d),migration,developmentA.doffilariformlarvamayinvadehostskeletalmusculaturePathogenicity

鉤蟲感染鉤蟲病Thecourseofhumanhookwormdiseasecanbedividedintothreephases:

invasionphase

migrationphase

intestinalphase

Invasionphaselarvalinvasionofskin鉤蚴性皮炎itching,erythematouspapular,

vesiculareruption(withorwithoutedemaorenlargementoflymphnodes)secondarybacterialinfectioncreepingeruptionMigrationphase肺部損害themajorfeaturesarepulmonarymanifestationseverecases:

Loffler’ssyndromeorcoughing,dyspnea,pulmonaryinfiltrate,Eosinophilia,nausea,vomiting-----Wakanadisease

成蟲所致病變

消化系統(tǒng)的癥狀nausea,vomiting,abdominalpain,diarrhea,constipation--------intestinalcomplaints

慢性失血引起貧血anemia------bybuccalcapsule&‘teeth’toburrowthroughthemucosa,feedinguponblood

Intestinalphase貧血的原因：成蟲吸血：吸血量咬附部位粘膜滲血：咬附點(diǎn)滲血量蟲體吸血可以經(jīng)常更換咬附部位，造成新的損傷，原傷口還繼續(xù)滲血

移位傷口滲血量造血物質(zhì)吸收障礙；小細(xì)胞低色素性貧血Salivarysecretionsofthewormscontainanticoagulantsthatfacilitatebloodfeeding

A.d0.15

–0.26ml/worm/24hrs(3or6-8yrs)eggoutput10000to30000/dN.a0.03–0.05ml/worm/24hrs(3yrsor15yrs)eggoutput5000to10000/dKoilonychia(spoon-shapednails)duetoseverechronicirondeficiency.chlorosischildrenwithsevereinfectionshowsignsofproteinmalnutrition

(abdominaldistention,facialedema&hairloss)childrenwithchronichookwormanemia

physicalgrowthretardation deficitsinchildcognitionandintellectualdevelopment. reversedbyadministrationofanthelminthicdrugsprogressivecardiacinsufficiency-----congestiveheartfailure3mlto100ml/dayinmildorsevereinfection

另外與患者原來(lái)的健康狀況Geophagy(allotriophagy)(Pica):ahabitualingestionofnonfoodsubstances,oneofdiversecauseisirondeficiencyanemia(soil,wood,charcoal,paper)異嗜癥也許是鉤蟲病診斷的一個(gè)線索Infectionininfantorchildren---severestuntedgrowthdie嬰兒鉤蟲?。贺氀獓?yán)重、發(fā)育極差、合并癥多、死亡率高。經(jīng)胎盤經(jīng)乳汁經(jīng)皮膚LaboratoryDiagnosis----------i