Free-living, amphizoic and opportunistic amebas
Free-living, amphizoic and opportunistic amebas
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DOI：
10.1111/j.1750-3639.1997.tb01076.x
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发表时间：
1997-01-01
期刊：
影响因子：
6.4
通讯作者：
Visvesvara, GS
中科院分区：
文献类型：
--
作者：
Martinez, AJ;Visvesvara, GS
阿米巴属，棘阿米巴属和巴拉姆西亚属是自由生活的，两栖动物和机会主义的原生动物，在自然界中无处不在。这些变形虫存在于世界各地的土壤、水和空气样本中。在过去10年中，这些阿米巴原虫引起的人类感染涉及脑、皮肤、肺和眼睛的病例显著增加。由这些原生动物引起的感染在流行病学、免疫学、原生动物学、病理学和临床特征上存在显著差异。致病性福氏耐格氏杆菌的感染是通过接触池塘、游泳池和人工湖中的污染水而获得的。炎热的夏季气温升高或发电厂的温水有利于福氏奈氏菌的生长。福氏阿米巴是一种嗜热阿米巴，在热带和亚热带气候下生长良好。被称为原发性阿米巴脑膜脑炎（PAM）的中枢神经系统感染是由福氏奈瑟菌引起的，其特征是在接触后3-7天发生急性暴发性脑膜脑炎，导致死亡。受害者是健康的年轻人，最近有过与水有关的体育活动史。入口是嗅觉神经上皮。病理改变为急性出血性坏死性脑膜脑炎，伴中度化脓性渗出，主要发生在脑底部、脑干和小脑。在主要位于血管周围的中枢神经系统病变内可见滋养体。迄今已报告179例；仅在美国就有81家。Balamuthia mandrillaris和几种棘阿米巴是致病性的“机会性”自由生活阿米巴，可引起人类和动物的肉芽肿性阿米巴脑炎（GAE）。GAE是一种感染，通常见于身体虚弱、营养不良的个体、接受器官移植免疫抑制治疗的患者和获得性免疫缺陷综合征（艾滋病）。肉芽肿成分可以忽略不计，特别是在免疫功能低下的个体中。病理上，这些变形虫产生斑片状、慢性或亚急性肉芽肿性脑炎，伴有滋养体和囊肿。可能通过呼吸道或皮肤溃疡通过血液传播到达中枢神经系统。截至1996年10月1日，全球共报告了166例GAE病例，其中棘阿米巴103例，巴拉穆西亚63例。在这103例由棘阿米巴引起的病例中（仅在美国就报告了72例，艾滋病报告了50例）。众所周知，几种棘阿米巴也可引起慢性视力威胁角膜溃疡，称为棘阿米巴角膜炎（AK），主要发生在隐形眼镜佩戴者或角膜轻度擦伤的个体中。全世界已记录了数百例AK病例。
Amebas belonging to the genera Naegleria, Acanthamoeba and Balamuthia are free-living, amphizoic and opportunistic protozoa that are ubiquitous in nature. These amebas are found in soil, water and air samples from all over the world. Human infection due to these amebas involving brain, skin, lung and eyes has increased significantly during the last 10 years. The epidemiology, immunology, protozoology, pathology, and clinical features of the infections produced by these protozoa differ strikingly.Infection by the pathogenic Naegleria fowleri is acquired by exposure to polluted water in ponds, swimming pools and man-made lakes. Raised temperatures during the hot summer months or warm water from power plants facilitate the growth of N. fowleri. IV. fowleri is a thermophilic ameba that grows well in tropical and subtropical climates. The CNS infection, called Primary Amebic Meningoencephalitis (PAM), produced by N. fowleri is characterized by an acute fulminant meningoencephalitis leading to death 3-7 days after exposure. Victims are healthy, young individuals with a history of recent water-related sport activities. The portal of entry is the olfactory neuroepithelium. The pathologic changes are an acute hemorrhagic necrotizing meningoencephalitis with modest purulent exudate, mainly at the base of the brain, brainstem and cerebellum. Trophozoites can be seen within the CNS lesions located mainly around blood vessels. Thus far 179 cases have been reported; 81 in the USA alone.Balamuthia mandrillaris and several species of Acanthamoeba are pathogenic ''opportunistic'' free-living amebas which cause Granulomatous Amebic Encephalitis (GAE) in humans and animals. GAE is an infection, usually seen in debilitated, malnourished individuals, in patients undergoing immunosuppressive therapy for organ transplants and in Acquired Immunodeficiency Syndrome (AIDS). The granulomatous component is negligible, particularly in immunocompromised individuals. Pathologically these amebas produce a patchy, chronic or subacute granulomatous encephalitis with the presence of trophozoites and cysts. The portal of entry is probably through the respiratory tract or an ulceration of the skin reaching the CNS by hematogenous spread. As of October 1, 1996, 166 cases (103 due to Acanthamoeba and 63 due to Balamuthia) of GAE have been reported from around the world. Of these 103 cases due to Acanthamoeba (72 have been reported in the USA alone, > 50 in AIDS), It is well known that several species of Acanthamoeba can also produce, chronic sight threatening ulceration of the cornea called Acanthamoeba keratitis (AK), mostly in contact lens wearers or in individuals with minor corneal abrasions. Hundreds of cases of AK have been documented world wide.