蛔虫、钩虫、蛲虫课件.ppt

1、Introduction to the Helminths 蠕虫蠕虫Helminths means worms,multicellular organisms.Phylum Class Nemathelminthes Nematoda(round worm)线虫纲线虫纲 线形动物门线形动物门 Platyhelminthes Tremetoda(flatworms)吸虫纲吸虫纲 扁形动物门扁形动物门 Cestoda 绦虫纲绦虫纲The Nematodes 线虫线虫 There are many,many nematodes2006 诺贝尔奖:干扰机制2002年诺贝尔奖：程序性细胞死亡C.Eleg

2、ansCylindrical,non-segmented,bilaterally symmetrical and sexes separatePseudocele 原体腔原体腔(pseudocoelom)The body wall:cuticle 角皮层角皮层 hypodermis 皮下层皮下层 longitudinal muscle 肌层肌层Holomyarian type(Whipworm)Polymyarian type (Ascarids)Meromyarian type (Hookworm)The arrangement of the somatic muscles Digestiv

3、e systemMouth pharynx esophagus intestine anus咽管食管肠管肛门Reproductive system male reproductive system Testis seminal vesicle 睾丸睾丸 储精囊储精囊 vas deferens 输精管输精管 ejaculatory duct 射精管射精管 Most females usually have two ovaries，oviducts and uterus.ovaryoviduct uterus.ovaryoviduct uterus.卵巢卵巢 输卵管输卵管 子宫子宫 vulva-v

4、agina 阴门阴门 阴道阴道nervous system Consist of:circumesophageal nerve ring 咽管神经环 and2 or 4 longitudinal nerve trunks 神经干神经干 Excretory system Excretory pore is anterior.排泄孔排泄孔No flame cells are present.life cycle M1 M2 M3 M4 Egg L1 L2 L3 L4 Adult larva (male&female)Kinds of life cycle in nematodes Ascaris

5、lumbricoides Trichuris trichiura Enterobius vermicularis HookwormsIndirect life cycle:Indirect life cycle:intermediate host is necessary intermediate host is necessary Trichinella spiralis FilariaDirect life cycle:Direct life cycle:Intermediate host is not necessary Intermediate host is not necessar

6、y土源性线虫（肠道线虫）生物源性线虫Pathogenesis1)Larvae：(1)dermatitis caused by cutaneous invasion and subcutaneous migration of larva;(2)injury to organs or tissues by migration of larvae in the body2)Adults：(1)injury to intestinal mucosa caused by the parasites living in gastro-intestinal system(2)injury to lympha

7、tic system,muscles or nervous system caused by the parasites living in tissuesWhat about Egg？INTESTINAL HELMINTHS Ascaris lumbricoides(roundworm)似蚓蛔线虫似蚓蛔线虫Trichuris trichiura(whipworm)毛首鞭形线虫毛首鞭形线虫 Enterobius vermicularis(pinworm)蠕形住肠线虫蠕形住肠线虫Ancylostoma duodenale and Necator americanus(hookworms)钩虫钩虫

8、 2004年第二次寄调Ascaris lumbricoides (ascarids)Adults live in intestine of human,cause Ascariasis(蛔虫病蛔虫病)；Human is the only definitive host of this parasite.1 billion world widethe infective rate in China 12.72%Hookworms Five species of hookworms:Ancylostma duodenale 十二指肠钩口线虫 Necator americanus 美洲板口线虫Anc

9、ylostma ceylanicum 锡兰钩口线虫Ancylostma caninum 犬钩口线虫Ancylostma brazilience 巴西钩口线虫Adult live in the intestine and take blood from the host,cause hookworm disease.Number of humans infected is estimated at 1.2 billion with 50,000 to 60,000 deaths each year.国内：6.12%Enterobius vermicularis(Pinworm)Almost an

10、ybody can become infected with this parasite，especially children.The worldwide infection is about 210 million 国内：10.28%MorphologyMorphology Adult of Ascaris lumbricoides the largest nematode parasites of humans Creamy white or pinkish in color elongate and cylindrical Female:measuring 35cm long,post

11、erior end is straightMale:measuring 25cm long，posterior end is curved.Morphology Adults of Ascaris lumbricoides Three lips around the mouth in “品品”type and possess small teeth Morphology Adults of Ascaris lumbricoides 50 mm long with a slender anterior and a thicker posterior end The male is smaller

12、 and has a coiled posterior end Morphology Adults of Trichuris trichiura Morphology Adults of Enterobius vermicularis Adults:pin-like,white,small wormFemale showing esophageal bulb&cephalic alae Male with curved posterior end,Female has a long pointed end.咽管球头翼Morphology Adults of hookwormsAdult:Sle

13、nder,pinkish or creamy-gray in color,about 10mm in length.Females:9-13 mm long with egg-filled uterus Males:7-11 mm long,Posterior end forms a Copulatory bursa (交合伞交合伞)Morphology Adults of hookwormsMorphology of Ancylostoma duodenaleBuccal capsule contains 2 pairs of large ventral(anterior)teeth Cop

14、ulatory bursa is at posterior end and contains 2 thin spicules that separate distally.口囊口囊交合伞Morphology of Necator americanusBuccal capsule contains a pair of ventral and dorsal cutting plates.Copulatory bursa contains spicules that are fused distally.shape “c”,1cm “s”,1cmbuccal capsule flat and ova

15、l-shape oval-shape two pairs one pair cutting platesCopulatory bursa round oblate spicule two,separated two,fused at their ends A.duodenale N.americanusDifference between A.duodenale and N.americanus Morphology larva of hookworms rhabditiform Larva 杆状蚴杆状蚴 filariform larva :infective stageEggs are un

16、embryonated when passed in the feces.Embryonation occurs in the soil.Unembryonated egg in fecesbroadly oval yellowish to brown in color Thick shellovum protein coat fertilizedMorphology Eggs of Ascaris lumbricoides unfertilized and fertilized egg Decorticated egg(lost outer albuminous coating)Embryo

17、nated egg in soilMorphology Eggs of Ascaris lumbricoides Morphology Eggs of Trichuris trichiura size:50-54 m by 22-23 m,smaller than Ascarids Shape：a typical barrel Color：yellow-brown unstained two polar plugsShell：quite thick Contains：unembryonated eggMorphology Eggs of Enterobius vermicularissize:

18、smaller than AscaridsShape：oval,flattened on one side Color：colorlessShell：quite thick Contains：an undeveloped larva insideShape:oval-round Shell:thin with smooth and colorless(transparent)eggshell Size:57-76 m by 35-47 mContains:clear space between the egg-shell and the ovum.Usually 2 to 16 cells i

19、n fecesMorphology Eggs of hookwormsMorphology Eggs of hookwormsLife cycle Life cycle of Ascaris lumbricoides Adult egg infective egg larva Ingested by man migrationLife cycleMigration of larva in the host:Vessels of intestine liver heart lungs trachea pharynx intestine(swallowed)Life cycle of hookwo

20、rmLife Cycle Adult egg rhabditiform filariform larva larva Swallowed pharynx trachea lung circulation Penetrate skin Life cycle of Enterobius vermicularis Life cycle ingestedAdultegginfective egg(in lumen of cecum)PathogenesisPathogenesis of Ascaris lumbricoides 1)larvae:Ascaris PneumonitisAsthma La

21、rva in section of lungPathogenesis2)Adults：(1)Malnutrition(2)Disorder of digestive system:main complaint-abdominal pain(3)Allergic responses anorexia(食欲不振食欲不振)nausea(恶心恶心)vomiting(呕吐呕吐)diarrhea(腹泻腹泻)Complication 并发症并发症 penetrate to bile ductspenetrate to the pancreatic and the appendix 胆道蛔虫症胰腺阑尾inte

22、stinal obstruction 肠梗阻 Ectopic parasitism 异位寄生异位寄生1.cause irritation(pruritus 搔痒搔痒)of the anal region Secondary bacterial infection in areas scratched raw may occur.2.vaginitis and rarely salpingitis in young girls.阴道炎阴道炎 输卵管炎输卵管炎3.cause mental anguishPathogenesis of Enterobius vermicularis Pathogen

23、esis of hookworm1.Local dermatitis(ground itch)钩蚴性皮炎钩蚴性皮炎 2.Pulmonary(pneumonia-like)symptoms (symptoms are not as severe as Ascaris migration)3.Anemia a.The worm sucks blood and the wound oozes blood A.duodenale takes 0.26 ml/day;N.americanus 0.03 ml/dayb.The worm usually changes its sucking site c

24、.Disfunction of intestine to absorb irongradually produce an iron-deficiency anemia4.gastroenteric symptoms 胃肠道症状胃肠道症状 Slight,intermittent abdominal pain 5.Aberration of appetite(geophagy 异嗜症异嗜症).loss of normal appetite and desire to eat soil or un-normal materials6.Hookworm diseases of infant7.eosi

25、nophiliaLaboratory DiagnosisLaboratory Diagnosis1.By identifying the eggs 1.direct fecal smear 2.brine-floatation method（饱和盐水浮聚法）（饱和盐水浮聚法）3.Scotch tape technique(cellophane tape impression)透明胶纸黏贴法透明胶纸黏贴法 4.Larval cultivation (钩蚴培养法)2.By identifying the adults3.therapeutic testEpidemiology distributi

26、onBasic conditions in parasitic epidemiologyPatients and infected personsl Souce of infectionl Mode of transmission(Factors of prevalence)For round worm For hookworm Via mouth Warmer and poor sanitation Inadequate disposal of feces Using nightsoil as fertilizerVia skin Bare-foot walkingOthers:Oral（A

27、.doudenale)PlacentaMothers milkParatenic hostsl Susceptible population“Hand-to-Mouth”Transmission retroinfection through anus inhalation of ova For pinworm Epidemiology the reason for wide distribution of Ascaris l1.simple life cycle2.high reproductive capacity(240,000 eggs per day)3.resistance of e

28、gg(due to presence of ascarosidal)4.social customs and habitsTreatment Prevention and control Treatment of patients and carriers,Blockade of the route of transmission Protection of the susceptible population (personal prophylaxis)Chemoprophylaxis,vaccines,other preventive measuresTreatment Preventio

29、n and controlTreatment:MebendazoleMebendazole（甲苯哒唑）（甲苯哒唑）AlbendazoleAlbendazole（阿苯哒唑，肠虫清）（阿苯哒唑，肠虫清）To prevent re-infection of E.v,treat the whole family.Others for hookworm diseases?透热疗法 纠正贫血Prevention and control:hygienic control of food,fecesGood hygiene is the best preventive measureWash all bed clothes and bedding in hot water to kill infective eggs of E.v.avoidance of contact with infected fecal materialOthers?Dog and Cat HookwormsHUMANS may serve as accidental hosts of these hookworms when the filariform larvae penetrate human skinCreeping Eruption匍形疹