Wilson M D, Boakye D A, Mosi L, Asiedu K
Department Of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, P.O. Box LG 581, Legon, Ghana. mwilson@
Ghana Med J. 2011 Mar;45(1):31-4. doi: 10.4314/gmj.v45i1.68920.
Buruli ulcer disease caused by Mycobacterium ulcerans results in extensive destruction of skin and soft tissue and long-term functional disabilities that ultimately require surgery and rehabilitation. The disease is associated with aquatic and swampy environments with the mycobacterium occurring in biofilms, soil, aquatic insects, fish and wildlife however, the mode of transmission to humans remains an enigma. Current transmission ideas including bites from predatory water bugs and mosquitoes, do not explain satisfactorily the spasmodic disease distribution in human populations. Here we argue that Acanthamoeba species are the natural hosts of M. ulcerans and are mainly responsible for disease transmission because; (i) Acanthamoebae are known natural hosts of several microbial pathogens including M. marinum, M. avium and Legionella pneumophila, (ii) culture of slow-to-grow microbial pathogens hosted in nature by Acanthamoeba spp is enhanced when the media is seeded with the protozoa, (iii) acanthamoebae and M. ulcerans share similar bio-ecological and epidemiological settings, (iv) documented evidence that prior growth of L. pneumophila and M. avium in acanthamoebae influences entry mechanisms, intracellular growth and virulence in human monocytes, (v) Acanthamoeba spp also infect humans and cause diseases via routes of openings including broken skin and sites of trauma similar to M. ulcerans and (vi) M. ulcerans is rather a fastidious intracellular organism as recent analysis of the genome indicate. We argue further that temperature plays a significant role in transmission determining the fate of either the intracellular microbe or the host cells. Also, Acanthamoeba-pathogen association has a long evolutionary history because the same set of bacterial genes and gene products e.g. in L. pneumophila are required for survival in both mammalian and protozoan host cells. We suggest that the involvement of Acanthamoeba in the transmission of M. ulcerans to humans better explains the disease's epidemiology.
由溃疡分枝杆菌引起的布鲁里溃疡病会导致皮肤和软组织的广泛破坏以及长期功能残疾，最终需要手术和康复治疗。该疾病与水生和沼泽环境有关，分枝杆菌存在于生物膜、土壤、水生昆虫、鱼类和野生动物中，然而，其传播给人类的方式仍然是个谜。目前关于传播的观点，包括掠食性水蝽和蚊子的叮咬，都不能令人满意地解释该疾病在人群中突发性的分布情况。在此我们认为棘阿米巴属物种是溃疡分枝杆菌的天然宿主，并且主要负责疾病传播，原因如下：（i）棘阿米巴是几种微生物病原体的已知天然宿主，包括海分枝杆菌、鸟分枝杆菌和嗜肺军团菌；（ii）当在培养基中接种原生动物时，棘阿米巴属在自然界中所宿主的生长缓慢的微生物病原体的培养会得到增强；（iii）棘阿米巴和溃疡分枝杆菌具有相似的生物生态和流行病学背景；（iv）有文献证明，嗜肺军团菌和鸟分枝杆菌先前在棘阿米巴中生长会影响其进入机制、细胞内生长以及在人类单核细胞中的毒力；（v）棘阿米巴属也会感染人类，并通过包括破损皮肤和创伤部位等开放性途径引发疾病，这与溃疡分枝杆菌相似；（vi）正如最近对基因组的分析所示，溃疡分枝杆菌是一种相当挑剔的细胞内生物。我们进一步认为温度在传播过程中起着重要作用，决定着细胞内微生物或宿主细胞的命运。此外，棘阿米巴与病原体的关联有着悠久的进化历史，因为嗜肺军团菌等同一组细菌基因和基因产物在哺乳动物和原生动物宿主细胞中生存都是必需的。我们认为棘阿米巴在溃疡分枝杆菌传播给人类过程中的作用能更好地解释该疾病的流行病学情况。
