醫(yī)學人體寄生蟲學 節(jié)肢動物二

ArthropodsII

TeachingpointsClassInsecta:flea,sandfly,louse,bedbug,cockroachClassArachnida:tick,itchmite,folliclemite,chiggermiteOrdersiphonapteraMorethan2000speciesintheworldand450speciesinChinaEcto-parasitesofmammalianandbirdsⅠFleas

SomespecieofClassInsectaLaterallycompressedWinglessThe3rdpairoflegsadaptedforjumpingPresenceofpygidium:peculiarsensoryorgantodetectaircurrentsSomespecieofClassInsectaAdultPupaLarva

(legless,segmented,3larvalinstars)EggLifecycleoffleaBothsexescantakeblood

MainHarmofflea:

Diseasetransmission

Mainreasonsforagoodvector

A.Verysensitivetobodytemperature.B.Plaguebacteriarapidlymultiplyandblocktheproventriculus.C.Strongabilityofanti-starvation.

MainHarmofflea:

Diseasetransmission1.Plague(black-death)Pathogen:Yersiniapestis

Vectors:

Pulexirritans（人蚤）;Xenopsyllacheopis(客蚤)2.Endemictyphus

:

Rickettsiamooseri

transmittedbyX.cheopis

proventriculusWhentakesabloodmeal,theplagueorganismrapidlymultipliesandblockstheflea’sproventriculus.Whilethefleasfeedsagain,itisunabletoengorgeandisforcedtoregurgitatebloodandthebacteriafromtheproventriculusintothehost.Verysmall(1.3-3.5mm)HairybodyWingsheldina“V”abovethebodyWeakflyinginsectsActiveatdawnorduskSomespecieofClassInsectaⅡSandfliesVectorsofLeishmanaeCutaneouslesion(closeup)CutaneousLeishmaniasisVisceralForm(Kala-Azar）DorsoventrallyflattenedWinglessProtuberanceoftibiaandclawsformgrippingorganBlood-feedingectoparasitesSomespecieofClassInsectaⅢLiceCrablouse:Pubes,eyelashHeadlouse:baseofhairBodylouse:underwear

2-4mm1.5-2mmPubiclouse:pubes,eyebrowsoreyelashesLifecycleoflouse

Allstagesandbothsexesfeedsolelyonblood.Obtaindailybloodmealstosurvive

Injectsalivaintothewound;meanwhilefecesarecontinuallypassedontotheskin

HuntinglicebycandlelightbyAndriesBoth,ca1630(NationalGallery,Budapest)

WorldWarII-eraAmericanposter,createdtopreventoutbreaksofpediculosisamongservicemen.PediculosiscapitisThemostcommonsymptomofinfestationispruritus(itching)onthehead.Bitescanbeseen,especiallyintheneckoflong-hairedindividualswhenthehairispushedaside.PediculosispalpebrarumLouse-bornedisease

BodyLice(asvectorsofdisease)1.

Epidemictyphus

Rickettsiaprowazekii（普氏立克次體）2.Trenchfever

Rochalimaeaquintana3.Louse-bornerelapsingfever

Borreliarecurrentis

（包氏螺旋體）ⅣBedbugsSomespecieofClassInsectaCimexhemipterus

the"tropicalbedbug"Cimexlectularisthe"humanbedbug"

FivenymphalinstarsrequirebloodmealstoproceedCharacteristicallybite2-3timesinsuccessionoverperiodofafewminutestoengorgethemGroupslivinginavarietyofhumanhabitations(bedding,clothesanddarkspaces),usuallyappearatnightSomespecieshavealsobeenfoundtocarryHepatitisBinIndiaBedbuginfestationofamattressandonamattressseam

Bedbugsonacarpet

Thebitesofbedbugscanleaveacolorlessweltalongwithanitchingorburningsensation.Agroupofbedbugsfeeding.Thesmalleronesarenymphs.Notetheraisedweltontheskinresultingfromtheirfeeding.

BedbugbitesfromtheLathamhotel,NewYorkCharacteristicallybite2-3timesinsuccessionoverperiodofafewminutestoengorgethem.Dorsal-ventrallyflattenedTwopairsofwingsQuickwalkerVCockroachSomespecieofClassInsectaBlatellagermanicaPeriplanetaamericana

OmnivorousinsectsServeasmechanicalvectorofpathogens:poliomyelitis,salmonellosis,amebicdysenteryandtoxoplasmosisIHofHymenolepisdiminutaAntigensofcockroachesgiverisetoallergicreaction.ClassArachnida

AraneaeAcariScorpionesGnathosoma(顎體)Idiosoma（軀體）4pairsoflegs;Noantennae;Nowings

TickOrderParasitifirmsFamily:Ixodidae(hardtick)Argasidae(softtick)

HardtickandSofttick(dorsalside)Gnathosoma

MorphologicaldifferencesbetweenhardticksandsoftticksScutumIdiosoma

IncompletemetamorphosisAllstagestakebloodChangehostfrequently

Hardtick:3hosttick;Softtick:multi-hosttickHardticksuckindayandfeedonhost7-9daysSoftticksuckatnightandonlyfeedonhostfromminutesto1hHypostomewithbarbpalpStingingorallergicreactions;Somefemalehardtickscontainsaneurotoxinintheirsalivawhichcouldcausetick

paralysis.DirectimpairmentDiseasePathogen

VectorDistributionForestencephalitisForestencephalitisvirusIxodespersulcatusNortheastChina,Russia,EuropeXinjianghemorrhagicfeverRNAvirusHyalommaasiaticumkozloniXinjiangProvinceinChinaEndemicrelapsingfeverBorreliapersicaandB.latyshevyiOrnithodorospopillipesAfrica,Asia,Europe,NorthAmericaandWesternChinaLymediseaseB.bergdorferiIxodespersulcatus,I.damminiUS,Europe,ChinaQfever

coxiellaburnetiOrnithodorospapillipesWidelydistributedTick-bornediseasesUseperpendiculartractiontoremovethetick,takingcarenottotwistthetick.SimulatedtickremovalUsingbluntforceps,graspthetickasclosetotheskinaspossibleItisimportanttoremovethetickcompletely,includingthemouthpartandthecementthetickhassecretedtosecureattachment.MaleventralsideItchmite（疥螨）FemaledorsalsideMaleventralsideOnthe4th

pairoflegsfemalewithbristles

whilemalewithambulacra"ScabiesLifeCycle"

LivinghabitatandLifecycle

Mateinskin,maleinseminatingimmaturefemales.Femaledigsburrowsand

depositeggintheupperlayersoftheepidermis.Eggshatchintolarvaeandthenexcavatenewburrowsandmaturein4days.Preferredsitesofinfestation:

Skinbetweenfingerstheshouldersbladesaroundthepenis

inthecreasesofthekneesandelbowsDirectimpairmentScabiesitchresultedfromthesensitizationtothetunnelling,thesecretoryandexcretoryproductsandeggs,severeatnight.Scabieslesionsundertheskin.Atypicallocationisonthehands,particularlythewebbingbetweenthefingers.

Crosssectionalviewoftheburrowscreatedintheepitheliumby

Sarcoptesscabei.ScabiesScabiesrashonthehands.Burrowsarevisible.

Scabiesburrowsbetweenthefingers.Thisisacommonplacetofindthescabiesmite.Scabiescanbetransmittedbyfrequentskin-to-skincontact.Diagnosisismostcommonlymadebylookingattheburrowsorrash.Scabies

Rash,septicpustules（膿皰）maydevelopafterscratching.Folliclemite（蠕形螨）Ferociousappearance0.1to0.4mminlength4pairsofstubbylegsDemodexBrevis:insebaceousglands

Itcauseinflammationinsebaceousglandsandworsenacneandroughupourskin.DemodexFolliculorum:inhairfollicles

Itcauseswideningofthefolliclepores,whichresultsininflammationandhairlossaroundthem.

Mostcommonlyoccurontheforehead,malarareasofthecheeks,nose,nasolabialfold,chin,

headskinandearhole.Mostpeopleacquirefolliclemitesearlyinlifefromhouseholdcontacts-primarilymaternal.DemodicidosisCharacterizedbyitching,inflammationandotherskindisorder.Mainsymptoms:skinrashes,hairlossandacne（痤瘡）.Treatment:washfacewithsulfuroussoap,andthenwashitoffwithlukewarmwater.Dustmite（塵螨）

Elongate

ellipticbodywithstriatedcuticletiny,microscopicbugs,0.2-0.4mminlengthInhabitation:commonlyinhabitmattresses,carpets,couchandhousedust.Oneofthemostsignificantallergens:harborstrongallergensintheirbodiesaswellastheirsecretions,excretaandshedskins.Anaphylaxis:dermatitis,allergicrhinitisandasthmaPrevention:reducemitespopulationinhome.Treatment:desensitizationtherapy(usingmiteextracts).Larvaof