人體寄生蟲學(xué)第二節(jié) 錐蟲

1、錐蟲 Trypanosome According to the geographic distribution & characteristic pathogenicity, members of trypanosomes that infect humans can be divided into two major groups. One group are African trypanosomes, which include Trypanosoma rhodesiense and Trypanosoma gambiense, the other group is American tr

2、ypanosome namely Trypanosoma cruzi 非洲錐蟲病非洲睡眠病 (African sleeping sickness) 由布氏岡比亞錐蟲和布氏羅得西亞錐蟲引起，由舌蠅傳播。1Morphology & life cycleTow distinct forms-the trypomastigote(錐鞭毛體) in the bloodstreamthe trypomastigotes exhibit three forms slender formlong, an undulating member, a free flagellum stumpy formshort,

3、 lacking flagelluma form intermediate between both-the epimastigote(上鞭毛體)-with a large nucleus, a kinetoplast, an undulating member, a free flagellum2345 舌蠅 舌蠅粗短型錐鞭毛體 上鞭毛體 循環(huán)后期錐鞭毛體 細長型鞭毛體 中間型鞭毛體粗短型鞭毛體對舌蠅具感染性細長型鞭毛體以二分裂法增殖，而粗短型則不增殖循環(huán)后期錐鞭毛體是感染期6Human beings become infected with Trypanosoma rhodesiense

4、or T.gambiense follwing the infection of metacyclic trypomastigotes(循環(huán)后期錐鞭毛體)the tsetse fly during the blood mealOnce introduced into the bloodstream, trypomastigotes spread & multiply rapidly, migrate to the cerebrospinal fluid (CSF)Tsetse fly get infected when it ingested stumpy trypomastigotes du

5、ring its blood mealThe stumpy trypomastigotes elongate, multiply, converting into epimastigote (上鞭毛體), then transform into metacyclic trypomastigotes, which are infective stage for human beings78PathogenicityEarly stage (初發(fā)反應(yīng)期): inflammatory reaction called trypanoosomal chancer occurs at the site o

6、f the bitereddening in the skin, a swelling 15 cm in diameter, enlargement of adjacent lymph nodesHemolymphatic stage (血淋巴期): the blood & lymph are invaded,headache, irregular fever develop, enlargement of lymph nodes -in the neck & supraclavicular area Winterbottoms sign羅得西亞布氏錐蟲病呈現(xiàn)急性經(jīng)過，致死亡前病程很少超過一年

7、，有的患者在中樞神經(jīng)系統(tǒng)未受侵犯之前即已死亡910Central nervous system stage (腦膜腦炎期): final stage of disease mental retardation, tremors, meningoencephalitis the patient slips into coma and death1112癥狀和體征癥狀出現(xiàn)率（%）頭痛78.7失眠/嗜睡74.4淋巴結(jié)腫大56.1感覺過敏51.1脾腫大42.5無力34.8肝腫大25.5營養(yǎng)不良25.2行為異常24.7食欲下降22.9行走困難21.7震顫21.0發(fā)熱16.1語言困難13.4異常動作10.

8、513Epidemiology T. gambiense is found in tropical West Africa & Central AfricaT. rhodesiense is found in East & Central Africa主要由舌蠅傳播 移植、輸血、注射事故也可傳播Blood transfusion, transplant are additional routes of transmission The antelope (羚羊) may serve as reservoir host保蟲宿主:羚羊14DiagnosisMultistep procedure:

9、clinical assessment examination of blood smearsbone marrow, or CSF for trypomastigotes antibody detectionIFA.ELISATreatment Suramin 早期療效100% Eflornithine（依弗鳥氨酸）早晚期會更有效Suramin is effective against African sleeping sickness when treatment is initiated early in the course of the disease, Eflornithine w

10、ill be more effective one15由 Trypanosoma cruzi引起美洲錐蟲病 Chagas disease,Trypanosoma cruzi is responsible for Chagasdisease由錐蝽 (reduviid bug vector)傳播。Trypanosoma cruzi16Morphology & life cycleamastigote: a nucleus, a kinetoplast, a blepharoplast, an axonemetrypomastigote: similar to that of African try

11、panosomesT. cruzi is most frequently transferred to a human host when a reduviid bug vector (錐蝽)defecates infective metacyclic trypomastigotes near the site of its blood meal17After entry into host, trypomastigotes invade surrounding cell & transform into amastigotes, which are multiply, destroy the

12、 host cells, convert back into trypomastigotes 非復(fù)制型的血流內(nèi)的錐鞭毛體The resulting trypomastigotes migrate into the blood, and penetrate additional cells in the body, transform back into amastigotes, the replication & destruction cycle repeat-heart muscle, liver & brain will become infected 復(fù)制型的細胞內(nèi)的無鞭毛體The t

13、rypomastigotes are transmitted back to the reduviid bug via a blood meal 循環(huán)后期錐鞭毛體隨錐蝽糞便排出于哺乳動物體表18 錐鞭毛體 無鞭毛體 球鞭毛體 上鞭毛體 循環(huán)后期錐鞭毛體 上鞭毛體 無鞭毛體The matacyclic trypomastigotes are then passed with the feces when the bug defecates near the site of its next blood meal, the cycle begins again錐蝽吸血錐蝽糞便污染 后位傳播或污染傳

14、播，有別于非洲錐蟲病的前位傳播或接種傳播19夜間吸血糞便中蟲體經(jīng)傷口侵入先天感染輸血傳播.2021Disease is named after Carlos Chagas, a Brazilian who discovered T. cruzi in conenosed bugs in 1910. 22Pathogenicity：人體所有有核細胞均是潛在的感染靶細胞 the parasite invade macrophage of the subcutaneous tissue at the site of infection, causing a local, edematous swel

15、ling called a chagoma, kiss bugs ( about 1-3 weeks after infection, fever, headaches, malaise, and prostration may develop)急性期 Chagoma、kiss bugs,伴發(fā)熱、頭痛等，也可肝脾腫大23Thatched roof hutEye infection (Romanas sign)2425In chronic stage: myocarditis, enlargement of colon and esophagus, hepatosplenomegaly 慢性期

16、急性后10-20y，心肌炎、巨食道、巨結(jié)腸Histologic section of heart muscle infected with T. cruzi amastigotes. 2627enlargement of colon28Normal heartChagas heartNormal intestineChagas intestineChagas Disease - Chronic Stage: 10-40 years after infection 20-30% of infected people develop serious symptoms Enlarged heart

17、Enlarged esophagus or bowel29克氏錐蟲臨床病程及癥狀30EpidemiologyT.cruci is found in South and Central America, rarely in North America主要經(jīng)錐蝽傳播 移植、輸血、胎盤或被錐蝽糞便污染的食物也可傳播，保蟲宿主犰狳。The highest prevalence of disease is in BrazilAdditional routes of T.cruci transmission include blood transfusion,transplacental, and ent

18、ry through the mucous membranes when the bug bite occurs near the eye or month3132Diagnosis Giemsa-stained blood slides lymph node biopsy giemsa-stained slides culture of bloodNNN mediumamastigotes serologic testsIFA, ELISA xenodiagnosis PCRTreatmentThe treatment of choice for infection with T.cruci is Nifurtimox（硝基呋喃類）333435Diagnosis Giemsa-stained blood slides lymph node biopsy giemsa-stained slides culture of b