第五節(jié) 其他毛滴蟲
一、人毛滴蟲
人毛滴蟲（Trichomonas hominis Daraine 1860)寄生于人體盲腸和結(jié)腸，其生活史僅有滋養(yǎng)體階段，無包囊。滋養(yǎng)體呈梨形，形似陰道毛滴蟲，具有3～5根前鞭毛和1根后鞭毛。后鞭毛與波動膜外緣相連，游離于尾端。波動膜的內(nèi)側(cè)借助一彎曲、薄桿狀的肋與蟲體相連。肋與波動膜等長，染色后的肋是重要的診斷依據(jù)。活蟲體可做急速而無方向的運(yùn)動。波動膜在運(yùn)動中起旋轉(zhuǎn)作用，而前鞭毛起推動作用。胞核單個(gè)，位于前端，核內(nèi)染色質(zhì)分布不均勻。胞質(zhì)內(nèi)含有食物泡和細(xì)菌。一根纖細(xì)的軸柱由前向后貫穿整個(gè)蟲體（圖10-7 )。
蟲體以縱二分裂法繁殖。滋養(yǎng)體在外界有較強(qiáng)的抵抗力，為感染階段。目前尚無證據(jù)表明人毛滴蟲對人體有致病作用。有報(bào)道認(rèn)為本蟲可導(dǎo)致腹瀉，調(diào)查表明，人毛滴蟲在腹瀉患者中的檢出率是健康人的幾倍甚至十多倍，但有人認(rèn)為腹瀉與本蟲感染相伴，并非本蟲所致。
可采用糞便直接涂片法鏡檢滋養(yǎng)體或用人工培養(yǎng)基（Boeck和Drobhlav二氏培養(yǎng)基)分離蟲體。
本蟲呈世界性分布，以熱帶和亞熱帶較為常見。感染率各地不同，我國為0.2%～9.4％，以兒童較為常見。本蟲感染途徑為糞—口傳播。誤食被滋養(yǎng)體污染的飲水和食物均可感染。治療首選藥物為甲硝咪唑（滅滴靈)，中藥雷丸療效也較好。
二、口腔毛滴蟲
口腔毛滴蟲（Trichomonas tenax Muller, 1773)寄生于人體口腔，定居于齒齦膿溢袋和扁桃體隱窩內(nèi)，常與齒槽化膿同時(shí)存在。生活史僅有滋養(yǎng)體階段，外形似陰道毛滴蟲，呈梨狀，有4根前鞭毛和1根無游離端的后鞭毛，波動膜稍長于陰道毛滴蟲，核單個(gè)，位于蟲體前部中央，含豐富染色質(zhì)粒，軸柱較纖細(xì)，沿蟲體末端伸出（圖10-8)，以縱二分裂法繁殖。
本蟲是否致病尚無定論。有學(xué)者認(rèn)為口腔毛滴蟲為口腔共棲性原蟲，但另有學(xué)者認(rèn)為與牙周炎、牙齦炎、齲齒等口腔疾患有關(guān)。曾有呼吸道感染及扁桃體隱窩內(nèi)查見本蟲的報(bào)道。實(shí)驗(yàn)診斷可用牙齦刮拭物作生理鹽水涂片鏡檢或作培養(yǎng)。滋養(yǎng)體在外界有較強(qiáng)抵抗力，室溫下可存活3～6天。接吻是本蟲的直接傳播方式；也可通過飛沫、食物、餐具等傳播。平時(shí)注意口腔衛(wèi)生是預(yù)防本蟲感染的最有效方法。
Summary This chapter discusses human protozoan parasites belonging to several different genera—Leishmania and Trypanosoma; Giardia and Trichomonas as well as the diseases caused by these protozoa.
Numerous species of Leishmania cause forms of leishmaniasis in various geographic areas, including visceral leishmaniasis (L. donovani), mucocutaneousal leishmaniasis (L. braziliensis) and cutaneous leishmniasis (both L. tropica and L. mexicana). Leishmania occurs as an intracellular amastigote in the mammalian host and as promastigote in the intestine of the sand flies, which act as vectors. The severity of disease depends on the infecting species and on the host’s immune response.
Trypanosoma is the pathogen of Trypanosomiasis, in which T. brucei causes African trypanosomiasis (Sleeping Sickness) and T. cruzi causes American trypanosomiasis (Chagas’ disease).
Giardiasis, caused by Giardia lamblia, may be asymptomatic or may cause a variety of intestinal symptoms, including chronic diarrhea, steatorrhea, cramps, bloating, and fatigue and weight loss. There is evidence that some animal Giardia strains may infect humans.
Trichomonas vaginalis is the pathogen of trichomoniasis, which is a common urogenital disease in women. Vaginitis, with foul-smelling discharge and small hemorrhagic lesions, may be present; frequency of urination and painful urination are common symptoms.
Another trichomonad parasite inhabits the intestinal tract in the area of the cecum. Th醫(yī).學(xué)全在線m.f1411.cnis parasite is called either T. hominis or, because most of these organisms in culture have five anterior flagella, Pentatrichomonas hominis. Trichomonad tenax inhabits the human oral cavity, occurring particularly in tartar, cavities, and at the gingival margins. Although considered nonpathogenic, it has been reported, rarely, in lung or thoracic abscesses.
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