Windsor J J, Johnson E H
Department of Microbiology and Immunology, College of Medicine, Sultan Qaboos University, Muscat, Sultanate of Oman.
Br J Biomed Sci. 1999;56(4):293-306.
Dientamoeba fragilis is a pathogenic protozoan parasite with a world-wide distribution. Although originally described as an amoeboid organism, it has been reclassified as a flagellate, on the basis of a number of electron microscopic and immunological findings. Except for its lack of a flagellum, D. fragilis closely resembles Histomonas and Trichomonas. Interestingly, a resistant cyst stage has not been demonstrated and it is unlikely that its trophozoites can survive successfully outside the human host. As a consequence of its higher than anticipated coincidence of infection with Enterobius vermicularis, transmission may occur via ova of this pinworm. D. fragilis infection may be acute or chronic, and has been reported in both children and adults. The most common clinical symptoms include abdominal pain, persistent diarrhoea, loss of appetite, weight loss and flatulence. Occasionally, eosinophilia, urticaria and pruritus have been described. Demonstration of the characteristic nuclear structure of D. fragilis, needed for a definitive diagnosis, cannot be achieved in unstained faecal material; therefore, permanently stained smears are essential. Treatment is recommended in symptomatic cases, and iodoquinol, tetracycline and metronidazole have been used successfully.
脆弱双核阿米巴是一种分布于全球的致病性原生动物寄生虫。尽管最初被描述为一种阿米巴样生物，但基于一些电子显微镜和免疫学研究结果，它已被重新分类为鞭毛虫。除了没有鞭毛外，脆弱双核阿米巴与组织滴虫和毛滴虫非常相似。有趣的是，尚未发现其有抗性的包囊阶段，并且其滋养体在人体宿主外不太可能成功存活。由于其与蠕形住肠线虫感染的同时发生率高于预期，传播可能通过这种蛲虫的虫卵发生。脆弱双核阿米巴感染可能是急性或慢性的，在儿童和成人中均有报道。最常见的临床症状包括腹痛、持续性腹泻、食欲不振、体重减轻和气胀。偶尔也有嗜酸性粒细胞增多、荨麻疹和瘙痒的描述。在未染色的粪便样本中无法观察到用于确诊所需的脆弱双核阿米巴的特征性核结构；因此，永久染色涂片至关重要。有症状的病例建议进行治疗，碘喹啉、四环素和甲硝唑已成功用于治疗。
