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1、Section4PrevalenceandHarmofParasiticDiseasesFirst-classepidemic:seriousharmtohumansandanimals,whichrequiresurgentandstrictmandatoryprevention,controlandextinguishingmeasures.TypeIIepidemics:thosethatcancausesignificanteconomiclossesandrequirestrictcontrolandextinguishingmeasurestopreventtheirspread.
2、Suchas:Toxoplasmosis,Echinococcosis;Trypanosomiasis;ChickencoccidiosisTypesIIIepidemics:commonandfrequent,whichmaycausesignificanteconomiclossesandneedtobecontrolledandpurified.Suchas:Schistosomiasisandfilariasis;TrichomoniasisTheharmofparasiticdiseasesHarmsandcharacteristicsofparasiticdiseasesEcono
3、miclossPublichealthimpacts:ofthesixmajortropicaldiseases,therearefiveparasitedisease:malaria,schistosomiasis,filariasis,leishmaniasisandtrypanosomiasis.Harmscharacteristics:ChronicinfectionInfestyounganimalsIntroducepathogenicmicroorganismsTheharmofparasitestothehost1.Mechanicalinjury1)When the para
4、site larvaepenetratetheskinofthehostandmigratethroughvarioustissues,they damage theskin and organs of varioustissues,causingwormholesandwormchannels,causing bleedingandinflammation.Necroticspotsformedbyalargenumberofroundwormlarvaemigratinginpigliver2)Specialorganssuchassuckers,kisses,mouthpocketsof
5、parasitesattachtothemucousmembranesofgastrointestinalorgansandotherorgans,causinglocaldamageStrongylus equinus inhaledintotheintestinalmucosaP.cervimigrateintheintestine3)Parasitesaccumulateintheintestinaltract,bileduct,pancreaticduct,lymphaticvessel,bloodvessel,andbronchusoftheparasiticsite,causing
6、blockagesandotherconsequences.Ascaris suum Dirofilaria immitis4)Someparasitesparasitizeorformgraduallyincreasingcystsinthehostorgans,stimulatingandcompressingtheparasiticorgansandsurroundingtissues,causingvariousdiseases.Hydatidcystintheliver5)Destructionoftissuecells,causingtissuedamageandanemia.If
7、chickencoccidiaschizontsproliferateintheintestinalepithelialcells,theintestinalmucosaiscongestedChickencoccidia2.Seizethehostsnutrition:Theparasitefeedsonthehoststissues,bodyfluids,orgastrointestinaltractcontentstomakethehostmalnutrition,weightloss,andanemia.3.Toxiceffectsonthehost:Metabolitesandsec
8、retionsexcretedbytheparasiteduringtheirlife,aswellasbodyfluidsreleasedduringthedeathanddisintegrationoftheparasites,mayhavetoxiceffectsonthehost,causinglocalorsystemicreactionsofthehostCholecystitisEggsofClonorchis sinensis 4.Infection causes secondary infection.Many parasitescausedamagetotheskinormucosaofthehost,creatingconditionsfortheinvasionofotherpathogens.Cattle Grubs 5.AffectpublichealthManyanimalparasiteshavetheabilitytoinfecthumansHookworm