westermani卫氏并殖吸虫

westermani卫氏并殖吸虫第1页/共17页I.morphology

1.Adult:Thebodyiselliptic,dorsallyitisconvex,ventrallyitisflattened,reddish-brownincolor,about7.5-12×4-6×1-3mm(length:width=2:1).Itlookslikehalfapeanut.Thesizesoftwosuckersaresub-equal.Theventralsuckerislocatedinthecentralpositionofthebody.Twotestes,theovaryandtheuterusaresituatedsidebyside.Thevitellariaiswelldeveloped.Theexcretorybladderextendsforwardtothelevelofpharynx.Thedigestivetractisdividedintotwoceca.第2页/共17页

AadultofParagonimuswestermani第3页/共17页AadultofP.westermani第4页/共17页2.Eggisirregularlyelliptic,goldenyellowincolor,80-110×48-60µinsize.Thethickandasymmetricshellwithadistinctoperculumenclosesanovumsurroundedbymorethan10yolkcells.3.Metacercariaisspherical,about300-400µwithtwolayersoftransparentwalls,incrabandcrayfish.第5页/共17页.

Theovalovahaveanoperculumandare80-110by48-80µm.Itisgoldenyellowincolor.Theshellisuneveninthickness.Thecontentisanovumandmorethan10yolkcells.第6页/共17页EggofP.westermani第7页/共17页II.Lifecycle

1.Infectivestage:metacercaria2.Infectivemode:eatingrawfreshwatercrabsandcrayfishwithmetacercariae3.Infectiveroute:bymouth4.Siteofinhabitation:lungs5.Intermediatehosts:1stint.hostismelaniasnail(川卷螺).2ndint.hostsarecrabandcrayfish.6.Reservoirhosts:carnivoressuchastiger,lion,wolf,fox,dog,leopard,catandetc7.Lifespan:5-6years

第8页/共17页第9页/共17页

penetratethediaphragmadolescentsadultsinlungseggs

Migratetothelungs

excystationInHumanBodyduodenum

Dischargedinsputum

maneatsrawcrabororinfeces

crayfishwithmetacercaria

────────────────────────────MetacercariaeEggsgetintowater

invadecrabInWater25-30℃

andcrayfish

3-4weeksMiracidiahatchout

invadesCercariaeMelaniasnail

EscapeasexualreproductionCercariaeDaughterrediaeMotherrediaeSporocysts第10页/共17页III.PathologyandSymptomatology

Adultsinhabitlungs,althoughotherorgansarealsoinvolved.1.Pathologicallesionsmaybeclassifiedinto4stages:(1)Invadingandmigratingstage:Afterexcystationtheadolescentspenetratetheintestinalwallandmigratetothelungs.(2)Suppurativestage.Thebleedingandinfiltrationofneutrophilsandeosinophilssurroundingwormsformacapsule,abscess.第11页/共17页

(3)Cysticstage,thecystwallisformedduetotheprogressivefibrosisofthesurroundingtissue.ThecysticcontentsarechocolateorrustythickfluidwitheggsandCharcot-Leydencrystals(夏科-雷登氏晶体）,whichlookslikesesamepaste.TheshadowofthecystcanbeseenonX-ray.Patientscoughouttherustysputumwhenthecystcommunicateswiththebronchioles.(4)Fibrous-scarstage,thewormsaredeadorescapefromthecyst.Theexudateandpusareexpelledorabsorbedandreplacedbyfibrous-scartissue.

第12页/共17页2.Clinicalmanifestation:

Paragonimiasismaybeclassifiedinto4types:(1)Pulmonarytype:

thesymptomsresemblepulmonarytuberculosis(结核)withlowfever,lossofappetite,nightsweating,chestpain,lossofweightandrustysputum.

(2)Braintype:manifestsepilepsy(癫痫),hemiplegia(偏瘫),monoplegia(单瘫),aphasia(失语),visualdisturbenceandresemblescerebralcystcercosis(脑囊虫病).

(3)Abdominaltype:abdominalpain，diarrheaordysenterywithblood,mucusandovainfeces.

(4)Subcutaneoustype:

thewanderingandpainlesssubcutaneousnodules.第13页/共17页IV.Diagnosis1.Sputumexamination:(1)Alkalidigestivemethod(10%NaOH),(2)Directsputumsmear2.Stoolexamination:(1)Alkalidigestion,(2)Watersedimentationmethod,(3)Directfecalsmear3.

BiopsyforSubcutaneoustype4.

CTforbraintype5.

Immunologicaltestsforreference.第14页/共17页V.TreatmentandPrevention

1.Treatment:Drugofchoiceispraziqantel.Othereffectivedrugsincludehexachloroparaxylol,bithionol(bitin).2.Prevention:(1)Healtheducation,(2)Avoideatingrawfreshwatercrabsandcrayfishes.(3)Avoidsputumandstoolgettingintowater.

第15页/共17页VI.Epidemi