年临床八年制钩虫、旋毛虫

1、Hookworm Hookworm infection is widely distributed in tropical & subtropical, where there are favorable environmental factor for hookworm spreading, including warm, high rainfall, soil pollution by human defection or fertilization with human feces and person walking with bare feet.Hookworm infection

2、is second only to ascariasis as the most common helminthic infection. Hookworm infection has almost eradicated from Europe and United States.Ancylostoma duodenale(十二指肠钩虫)- the small intestineNecator americanus (美洲板口线虫)-the small intestineAncylostoma cerlanicum (锡兰钩口线虫) -rarely infects human beingsAn

3、cylostoma caninum(犬钩口线虫)-rarely infects human beingsAncylostoma braziliense巴西钩口线虫-creeping erupting, 幼虫可感染人，引起幼虫移行症 钩虫是一类口囊发达的线虫，并在口囊内有锐利的切器，可损伤肠粘膜，吸食血液和组织液，使患者长期慢性失血，造成严重危害。钩虫寄生小肠引起钩虫Hookworm infection is contracted mainly by penetration of the skin or oral mucosa by the filariform larvae ( infecti

4、ve stage) of hookworm. Thus, barefoot farmers and children walking on contaminated soil or eating contaminated vegetables may e infected.Adults of A. duodenale Adults of N. americanusDifferences between two hookwormsMorphologyThe male worm is about 7 to 11 mm in length & about 0.4 mm thickThe female

5、 is larger, 9 to 13 mm long and o.6 mm thickFemales hookworm:9-13 mm long with egg-filled uterus Male hookworms:7-11 mm longPosterior end forms a copulatory bursaAdult: the adult are cylindricalwith the head bent sharply backwards, giving them a hooked appearance. The mouth of hookworm were well dev

6、eloped, with a pair of teeth or a pair of cutting plate.Egg (虫卵)Egg of two species are nearly indistinguishable. They are ovoid with a thin transparent shell and, measure 60 m X 40 m, a clear space that separates the shell from the yolk cells. The number of yolk cells in egg found in the stool varie

7、s from two to eight.Larvaa rhabditiform larva (杆状蚴): 275 X 16 m , the newly hatched larva feed actively upon bacteria and organic debris, grow rapidly to a size of 500 to 700 m in 5 days a filariform larva (丝状蚴 ): slender, nonfeeding the active filarform larva frequent the upper half-inch of soil an

8、d project from the surface-infective stage 头端 扁平，中间微凹 圆形，无凹陷 咽管矛 不明显 明显 鞘膜横纹 不明显 明显 尾端 逐渐变细 骤然变尖Ad 丝状蚴 Na 丝状蚴They survive best in shaded localities, such as light sandy or alluvial soil or loam covered by vegetation, they are protected from dry or excessive wetness at 0 C larva survive less than 2 w

9、ksat 11 C less than 24 hrsat 45 C less than 1 hrLife cycleHumans almost exclusively are hosts for both hookworm, while dogs also are common host for N. americanus. When eggs are expelled with feces, under optimal conditions ( temperature of 23-33C, shade, and sandy soil rich in organic material), a

10、rhabditiform-larva matures in 1-2 days & hatches from the thin shelled egg, feeds on bacteria & organic material in the soil. After two molts, it es a non-feeding, infective, filariform larva. Final host: man Infective Stage: Larva 3 or filariform larva Infective Route: by skin Food: blood and tissu

11、e fluid Site of inhabitation: small intestine Life span: Ad 15years, Na 3-7years Blood-lung migration: skin, cavum vena , right heart, lungs 成虫 卵 杆状蚴 丝状蚴（感染期） 经皮肤 粘膜移行途径皮肤 小血管 右心 肺 肺部微血管 肺泡 食道 咽 小气管Ad 保虫宿主：猪、狮、虎、狗、猴Na 转续 宿主：猩猩、猴、犀牛等 成虫寄生部位和摄食 Adult worm in small intestine产卵量 Ova product A.duodenale

12、produces 10000 to 30000 eggs per day N.americanus produces 5000 to 10000 eggs per day丝状蚴具有向上性、向湿性、向温性 character of filariform larva : strong thigmotaxis, moisture, thermotaxis (1-2 cm)Penetration skin or oral mucosa (A.d), migration, developmentA.d of filariform larva may invade host skeletal muscul

13、ature Pathogenicity 钩虫感染 钩虫病 The course of human hookworm disease can be divided into three phases: invasion phase migration phase intestinal phase Invasion phase larval invasion of skin 钩蚴性皮炎 itching, erythematous papular, vesicular eruption ( with or without edema or enlargement of lymph nodes) se

14、condary bacterial infection creeping eruptionMigration phase 肺部损害 the major features are pulmonary manifestation severe cases: Lofflers syndrome or coughing, dyspnea, pulmonary infiltrate, Eosinophilia, nausea, vomiting -Wakana disease 成虫所致病变 消化系统的症状 nausea, vomiting, abdominal pain, diarrhea, const

15、ipation -intestinal complaints 慢性失血引起贫血 anemia-by buccal capsule & teeth to burrow through the mucosa, feeding upon blood Intestinal phase贫血的原因：成虫吸血： 吸血量咬附部位粘膜渗血：咬附点渗血量虫体吸血可以经常更换咬附部位，造成新的损伤， 原伤口还继续渗血 移位伤口渗血量造血物质吸收障碍；小细胞低色素性贫血Salivary secretions of the worms contain anticoagulants that facilitate blo

16、od feeding A.d 0.15 0.26 ml/worm/24 hrs (3 or 6-8 yrs) egg output 10000 to 30000/d N.a 0.03 0.05 ml/worm/24 hrs (3 yrs or 15 yrs) egg output 5000 to 10000/dKoilonychia (spoon-shaped nails) due to severe chronic iron deficiency.chlorosischildren with severe infection show signs of protein malnutritio

17、n (abdominal distention, facial edema & hair loss) children with chronic hookworm anemia physical growth retardationdeficits in child cognition and intellectual development. reversed by administration of anthelminthic drugsprogressive cardiac insufficiency - congestive heart failure 3 ml to 100 ml/d

18、ay in mild or severe infection 另外与患者原来的健康状况Geophagy (allotriophagy) (Pica): a habitual ingestion of nonfoodsubstances , one of diverse cause is iron deficiency anemia(soil, wood, charcoal, paper)异嗜症 也许是钩虫病诊断的一个线索Infection in infant or children-severe stunted growth die婴儿钩虫病：贫血严重、发育极差、合并症多、死亡率高。经胎盘 经

19、乳汁 经皮肤Laboratory Diagnosis -identification of eggs in the stool 粪便检查 直接涂片法 饱和盐水浮聚法 Brine floatation method 钩蚴培养法： Culture of hookworm larva 定量检查 PCR检测 一个虫卵即可诊断，并可区别虫种 DNA (PCR) can be amplified from a single egg and identity speciesEpidemiology Hookworm is worldwide distributed N. americanus is foun

20、d mainly in moist tropical region such as Southeast Asia 分布较广泛 A. duodenale is found mainly in dry tropical region such as North Africa, North China 传染源：患者、带虫者传播因素：a. 适宜虫卵、幼虫发育、存活的条件 A shaded sandy or loam soil, which is a favorable culture medium for hookworm larva. A warm climate, which favors the

21、 development of the eggs and larva and promiscuous defecationMoisture, especially during the worm season of the years when egg and larva development are possibleb.粪便污染土壤 Contamination of the soil by egg-containing fecesc.生产、生活方式 person walking with bare feet.d.个体抵抗力加强卫生宣教，搞好饮食卫生粪便无害化处理加强卫生宣教Preventi

22、on & TreatmentTreatment of infected individuals 治疗病人和带虫者 mebendazole（甲苯达唑）100mg Bid3days albendazole（阿苯达唑） 400mg oncefor severe anemia administration of iron 同时纠正贫血 Sanitary disposal of human excrement 粪管预防感染Protective measures to prevent contact with infective larva鞭虫：Morphology and life cycleProla

23、psed rectum with adult T. trichiura.土源性线虫的生活史特点？感染期？ 感染途径？致病特点流行情况防治要点Trichinella spiralis旋毛虫(Trichinella spiralis)成虫寄生在小肠下部的肠壁，幼虫寄生在人体横纹肌中，引起旋毛虫病(Trichinellosis)，为人兽共患病。也是食源性寄生虫病，特点：地区性、群体性、食源性、季节性 (20140922)Trichinellosis is the disease among human and animal, a zoonosis.The infection is endemic i

24、n many areas of the world where raw or undercooked meat, mainly pork is consumed.雌虫产出幼虫经血流到肌细胞内成囊而具感染力Morphology Adult small & slender male: 1.5 mm X 0.04 mm female: 3.5 mm X 0.06 mm deposited larvaLarva enveloped, 0.25-0.5 mm X 0.21-0.42 mm Adult T. spiralis in small intestine - the worm is embedde

25、d within the cytoplasm of the columnar cells.Larval T. spiralis in muscle - the worm is embedded within the cytoplasm of the nurse cell.Nurse cell, a nurse cell is an infected cell in the disease trichinosis discovered by Dickson Despommier. A trichinella larva enters a cell and develops there, prob

26、ably as a way of concealing itself from the immune system. The parasite has evolved a way of stimulating blood vessel development around the cell, in order to receive the nutrients it needs. In trichinosis, nurse cells are invariably skeletal muscle cells; these are the only type of cell that can su

27、pport the parasite.Life cycle成虫和幼虫均寄生在同一宿主体内完成生活史需更换宿主Human infection results from consumption of meat, most communly poorly cooked pork, containing encapsulated larva.Life Cycle of Trichinella spiralisAdult T. spiralis in small intestine - the worm is embedded within the cytoplasm of the columnar c

28、ells.Larval T. spiralis in muscle - the worm is embedded within the cytoplasm of the nurse cell.Nurse cell, a nurse cell is an infected cell in the disease trichinosis discovered by Dickson Despommier. A trichinella larva enters a cell and develops there, probably as a way of concealing itself from

29、the immune system. The parasite has evolved a way of stimulating blood vessel development around the cell, in order to receive the nutrients it needs. In trichinosis, nurse cells are invariably skeletal muscle cells; these are the only type of cell that can support the parasite.Adult 4-6 days lympha

30、tic vessels heart lung spread Larva Larva another 2-3 days LarvaLarvae can survive only in the skeletal muscle & e encysted in 2 to 3 weeksPathogenicityTrichinellosis, mainly result from larval invasion of muscle & othertissues and the hyperimmune reaction of the host to the metabolic by-products and secretions of the larvae Invasion stage: due to penetration of adult female & larva into the mucosa & submucosa, begins 24 hrs after infection and lasts for 1 to 7 days asymptomatic or transient gastrointestipational complaints (1 week)Migration stage: begin