致病性自由生活阿米巴原蟲

Pathogenic Free-Living Amoebae

有別於痢疾阿米巴，致病性自由生活阿米巴原蟲無需進入人體或動物等宿主，棲息遍佈全球的土壤及水中，能在環境中完成其生活史。不論病患的免疫功能是否健全，這機會性感染仍然有致命的威脅。現今已知有四種致病原： Naegleria fowleri、Acanthamoeba spp.、Balamuthia mandrillaris、Sappinia spp.。其可能會引起致命性中樞神經感染、視力喪失及表皮感染。其感染本質是屬於機會性及致病性，而非寄生性。雖然臨床案例個案不多，但對這些阿米巴原蟲感染的早期診斷是非常重要，尤其腦膜腦炎，關係到患者的存活與否，然而迄今並無明確治療藥物的準則可供參考。

Pathogenic free-living amoebae are ubiquitous in nature. In contrast to Entamoeba histolytica, their life cycle can be completed without entering human or animal hosts. The opportunistic infections caused by these free-living amoeba can be life threatening, even if the patients are immunocompetent. Four such pathogens, Naegleria fowleri, Acanthamoeba spp., Balamuthia mandrillaris, and Sappinia spp., can cause lethal central nervous system infection, impaired vision, and cutaneous infection. The infections caused by these species are more opportunistic and pathogenic than parasitic. Early diagnosis is very important and is closely related to the prognosis of patients who do not receive timely treatment, although amoebic encephalitis in humans is rarely reported in the published literature. However, as yet, there are no treatment guidelines available for infections caused by pathogenic free-living amoebae.