大二下學(xué)習(xí)-寄生蟲課件4.filarial worm and trichinella spiralis

Filarialworm

WuchereriabancroftiBrugiamalayi

ProfessorJianpingChenⅠ.Morphology

1.

Adult:creamy-white,minute,thread-like,severalcentimeterslong;♂unitubularreproductivesystem,coiledtail;♀bitubularreproductivesystem,depositmicrofilariae

2.Microfilaria:

cylindrical,slender;enclosedinthin,colorlesssheathoriginallyformedfromelongatedeggshell;bodynuclei,cephalicspaceMicrofilariamf.ofW.bmf.ofB.mDifferencesbetweenmf.ofW.bancroftiandthatofB.malayi

mf.ofW.b.

mf.ofB.m

Size(um) 200-300×8220-250×6Appearance gracefuland irregular,kinky sweepingcurvescurvesCephalicspaceshort,1∶1 long,2∶1Somaticnucleiregularshape,ireegularshape, wellseparatedsizeandarrangementTailnuclei none 2Morphologyofmicrofilariamf.ofW.bmf.ofB.mmf.ofW.bmf.ofB.mmf.ofW.b.Cephalicspacemf.ofB.mmf.ofW.bmf.ofB.mmf.ofW.bmf.ofB.mTailnucleimf.ofW.b.mf.ofB.mmf.ofW.bmf.ofB.m3.Morphologyofinfectivelarva

(filariformlarva)infectivelarvaescapesfromtheproboscisofthemosquitoII.LifecycleLifecycle

1.

Locationofadult:W.b.:usuallyindeepregion,mainlyinvolvingthelymphaticsofthelowerextremitiesandtheinguinalregionsB.m.:usuallyinsuperficiallymphglands,mainlyinvolvingthelimbs

2.Host:

(1)Definitivehost

W.b.:man

B.m.:man,monkey,cat

(2)Intermediatehost:mosquito

(3)DiagnosticStage:Microfilariae

(4).Infectivestage:infectivelarva(Filariformlarva)

(5).Infectiveroute:skin

(6).Nocturnalperiodicityofmf.:Microfilariaeappearintheperipheralcirculationduringnight.Bydaytime,theyconcentrateinpulmonarycapillaries.Relatedtohost-parasitemutualadaptation.

(7).Pathogenicstage:adult中華按蚊淡色庫蚊VectorofB.malayiVectorofW.bancroftiMicrofilariae

→filariformlarva

：26-32℃

W.bancrofti

10-14d，B.malayi5-6.5donlydevelopment,nomultplyDevelopmentinmosquito

themicrofilariaareingestedandenterstomachbymosquitoduringbloodmeal.Inthegut,theylosetheirsheath,penetratethegut-wallwithinanhourortwotoenterthehaemocoele(血腔).topenetratethethoracicmusculature(胸肌),wheretheyrestandbegintogrow.Thelarvamoult(蛻皮)tothefirststagelarva,secondstagelarva,andfinallythirdstagelarva(infectivelarva),infectivelarvamigratetothesalivaryglandsofmosquito.Whenthemosquitobitesaman,thelarvaarereleasedfromthelipofproboscisofmosquitoandthelifecycleiscontinued.Developmentinmosquitoisusuallycompletedwithin10-14days(W.bancrofti)or6-6.5days(B.malayi).

Ⅲ. Pathology&Symptomatology

Secretions,excretionsoflivingworms;toxiceffectsofdeadwormsarethemaincausesofthepathologicalchanges.

1.Acutestage

Fever,lymphangitisandlymphadenitisaretheconspicuoussymptoms.lymphangitis2.Chronicstage

Mainlyduetothelymphaticobstructioninducedbytheadultworms.Adultwormsstimulatelymphanticvesselsdilationandthickeningofthelymphaticvesselslymphfluidgatheringinextremitieslymphoedemainflammatoryinfiltrationgranulomafibrosisobstruction

Elephantiasis,hydroceleandchyluriaarethethreemaincomplicationoffilariasis.elephantiasis

Elephantiasisisacommonsymptomofchronicfilariasis.Lymphaticruptureandlymphspillsintotissues,andthenprogressiveenlargement,coarsening（變粗）,corrugation（變皺）andfissuring（裂開）oftheskinandsubcutaneoustissue,withwartysuperficialexcrescences,developgraduallyuntilalegresemblesthatofanelephant.Thename‘elephantiasis”mayalsooccurinanupperlimb.elephantiasiselephantiasiselephantiasishydrocele

testis

Obstructionofspermaticcord(精索)andtestislymphatcsmaybecausedtohydroceletestis.ThemanifestationiscommonlyfoundfromthepatientwithW.bancroftiinfection.chyluriaObstructionoftheabdominalorthoraciclymphaticsmaybeleadtochyluria（乳糜屎）,chylousascite（乳糜性腹水）orachylouspleuraleffusion（乳糜性胸腔積液）.ThemanifestationiscommonlyfoundfromthepatientwithW.bancroftiinfection.

3.

Tropicalpulmonaryeosinophilia(TPE)Suchpatientswereonlydefined/foundbyfindingmicrofilariaeinthenodesorlung.Mostcommonofthesymptomaticclinicalsyndromesarerecurrentepisodesof‘filarialfever”,thetropicaleosinophiliasyndrome,higherlevelofIgEetc.

Ⅳ. Diagnosis

Basedonfindingmf.inperipheralblood

1.Freshbloodfilm2.Thickbloodfilm

Thethickbloodsmearwasmadeusing60lblood(2to3dropsofperipheralblood),afterdrying,thenstainedwithGiemsa.Optimalblooddrawingtimeisfrom10PMto2AMforW.bancrofti,from8PMto4AMforB.malayi.

3.Detectionofadult4.Immunologicaldiagnosis

mf.ofB.mMicroscopemf.ofW.bⅤ. Epidemiology

1.Distribution

2.Factorsconcerningtheepidemiology

Ⅵ. Prevention&treatment

1.Massdetectionandtreatment:

diethylcarbamazinecitrate(DEC,Hetrazan)

0.3%hetrazan/NaCL

2.Controlofmosquitoes3.Protectionofsusceptiblepopulation

海群生（乙胺嗪，Hetrazan）由小劑量開始，三周療法是第1日服50mg，第2日為50mg服3次，第3日為100mg服3次，第4～21日為服3mg/kg，每日3次。微絲蚴大量死亡后可引起發(fā)熱、周身不適、惡心、嘔吐等反應(yīng)，可服抗組胺藥。左旋咪唑可以有效。有水腫時可穿著彈性襪。有象皮病時可考慮外科手術(shù)。

TrichinellaspiralisⅠ.Morphology

1.Adult:Minute,thread-like;♂1.4-1.6mmlong,ovoviviparous,♀3-4mmlong,twoconspicuousconicalpapillaeinsteadofspicules

capillary-likeesophagusstichosomecomposedofarawofdisc-likestichocytes

unitubularreproductivesystemsofbothsexes

2.Encystedlarvaeinstriatedmuscle:

Larvaecyst

0.25-0.5mm×0.21-0.42mm.Thelongaxisofthecystparallelsthatofthemusclefiber.Oneortwolarvaewithsimilaresophagustoadultarecoiledinsideonecapsule.larva

王昕貢獻Larvaesurrounded

byacystwallofmuscle.II.LifecycleLifecycleLifecycleWhenmanconsumesraworrarefleshinfectedwithcystsofTrichnella,thecystsaredigestedoutofthemuscleinthestomach;thelarvae(firststage)areresistanttogastricjuice.Afterpassagetothesmallintestine,thelarvaepenetratethevilliofthesmallintestine,molt,anddevelopintomatureadultwithin48hours.Afterfertilization,thegravidfemaleburrowdeepintothemucosa,discharginglarvaebeginning5to46daysafterinfectionandcontinuingfor2to4weeksoroccasionallylonger.Larvaeentermostorgans,butpersistonlyinindividualskeletalmusclefibers.Increasingalmostten-foldinsize(to1.0mm)oversucceedingweeks,larvaegraduallyesurroundedbyacystwallofmuscle.Althoughthecapsulescalcifywithinsixmonthstotwoyears,thelarvaewithinremainviableformonthstoyears,rarelyfordecades.

1.Locationsofworm,Adult:smallintestine

Larva:striatedmuscle

2.

Infectivestage:encystedlarvae3.Infectiveroute:mouth4.Reservoirhost:manymammalssuchaspig,dog,rat,bearandwolf5.Twohostsarerequiredtocompletethelifecycle.Adultandlarveparasiteinonehost.6.Pathogenicstage:adult.larve7.HostPrimaryhost:Pigistheprimaryhost.Naturalhost:rodents,carnivoresandvariousotherspeciesofomnivorous（雜食）animalsaretheothernaturalhosts.Manisanaccidentalhostandisthedeadendfortheparasite.Why?Ⅲ. Pathology&Symptomatology

Threestages:1.Intestinalinvasion:mucosalhyperemia,punctatehemorrhagesandedema;malaise,mildfever,anorexia,andgastrointestinalcomplaints,particularlynausea,vomiting,colicanddiarrhea.1week.2.Muscleinvasion:Larvaemigratetostriatedmuscles.highfever,muscularpainandtendernessextendingthroughoutthebody;difficultyinbreathing,mastication,swallowingandspeechinheavyinfection.Penetrationofcardiacmusclemayleadtodeathfrommyocarditis.2~8weeks.3.Capsulation:Inflammationsubsidesandscartissueforms.Patientsgraduallymakearecovery.After3weeks. Ⅳ. Diagnosis

1.Musclebiopsy2.Immunologicalmethod

Excretion-secretionantigen,23kDa45kDa,49kDa,53kDaDiagnosis1.Musclebiopsy2.ImmunologicalmethodⅤ. Epidemiology

Cosmopolitan

HumanandanimalinfectionsofT.spiralisisworldwidedistribution.InChina,15provinceshavereportedtheinfectionsindividualsorpatients.InYunan,Thetrichinosisisthemostseriouszoonosis.

1.Therearemanyreservoirhost.2.Highresistantabilityofencystedlarvae3.Eatingraworinsufficientlycookedporkcontainingencystedlarvae

Threetypesoftransmission

cycleareseeninnature:Pig-to-pigcycleThisoccursinhumanpopulationduetotheirhabitoffeedinggarbagestopigs.PigsfedwithTrichinellascrap,pigmeatorcarcaseofanimalssufferfrominfection.Rat-to-ratcycleThisoccursbetweenrats/mouseandisnotdependentuponthepresenceorabsenceofinfectioninpigs.Pig-to-ratcycleThisplaysanimportantroleinkeepthetransmissionofinfection.Itwasreportedthattheprevalenceoftheinfectioninpigswas50.2%insomeendemicareasofHenanprovince.Eatingoringestingrawporkwithlarvacystismajorroutetoinfection.Thecysthavestrongerresistancetolowtemperature,freezingat-15℃for20dayscandestroytheparasitesinthepork.Cystcanbekilledat70℃,soeatingnon-properlyprocessedmeatproductsisthewaytorequireinfec