痢疾阿米巴原蟲感染

Amoebiasis

洪健清(Chien-Ching Hung)

《內科學誌》 29卷2期 (2018/04) Pp. 74-80

https://doi.org/10.6314/JIMT.201804_29(2).03

摘要

痢疾阿米巴原蟲(Entamoeba histolytica)仍然是全球重要的寄生蟲感染。在全球，痢疾阿米巴原蟲感染每年仍然造成大約100,000死亡案例。人類係因吃下污染了痢疾阿米巴原蟲的囊體(cyst)的飲水或食物感染，阿米巴囊體在小腸脫離囊體，形成營養體(trophozoite)，營養體可能持續寄生在大腸中、侵犯大腸或進入血液循環侵犯其他的組織器官；或者，再度形成囊體，隨糞便排出。人類感染痢疾阿米巴原蟲後，大多屬於無症狀帶原者；部分感染了可能發生大腸炎、組織器官膿瘍，特別是肝膿瘍。痢疾阿米巴原蟲感染的高危險群，包括：啟智教養院或精神病院院生、最近到過疫區旅遊返國的旅客、來自疫區的移民、男同性戀者等。痢疾阿米巴原蟲分為兩種：致病性(pathogenic amoeba)，亦即E. histolytica；與非致病性(nonpathogenic amoebas)，亦即E. dispar和E. moshkovskii。臨床檢測所採用的光學顯微鏡無法分辨E. histolytica和E. dispar 或E. moshkovskii。確認的診斷最好使用可以有效分別出致病性與非致病性阿米巴原蟲的工具，例如：抗原檢測和分子生物學工具。感染痢疾阿米巴原蟲，90%不會產生病症。而根據在越南的研究發現，一旦感染痢疾阿米巴原蟲50%以上的感染者腸道帶原的時間，會超過十個月之久。最近幾年來，台灣地區的痢疾阿米巴原蟲感染流行病學似乎改變了。經由血清流行病學的調查我們發現年紀介於20-39歲的男同性戀者血清陽性率高達12%亦即至少12%的男同性戀者曾經感染過阿米巴原蟲，相對於一般健康的人血清陽性率僅有0.12%。對於阿米巴大腸炎的治療最有效果、經驗最多的藥物是nitroimidazoles，特別是metronidazole (Flagyl)和tinidazole (Fazigyn)。對於極為嚴重的侵犯性痢疾阿米巴感染，有些專家建議加入emetine。目前對於痢疾阿米巴原蟲無症狀腸道感染帶原者的治療，具有療效的藥物有三類：dichloracetanilide derivatives, oral aminoglycosides,和5-hydroxyquinolines。這些藥物包括：diloxanide furoate (Furamide), paromomycin (Humatin),和iodoquinol (Yodoxin； diiodohydroxyquin)。Diloxanide furoate和paromomycin是使用經驗較多、專家較為推薦的首選藥物。對於發生病症的患者，除了必須通報至疾病管制局外，在接受7-10天metronidazole的療程後，患者也應再接受21天的iodoquinol，或者7天的paromomycin以減少復發。

關鍵字

大腸炎(Colitis) ； 腹瀉(Diarrhea) ； 肝膿瘍(Liver abscess) ； 男同志(Men who have sex with men) ； 口肛吻(Oral-anal sex)

並列摘要

Entamoeba histolytica infection remains an important parasitic disease with an estimated annual mortality of 100,000 cases globally. Amoebaisis is caused by ingestion of the cysts of E. histolytica. After excystation in the small intestine, trophozoites of E. histolytica may cause invasive infections, such as colitis and abscesses of the liver, lung, or other organs, though most individuals infected with E. histolytica are asymptomatic. People at risk for amoebiasis include residents in the institutions for mentally ill, recent travel or residence in endemic regions, immigrants from endemic regions, and men who have sex with men. Correct diagnosis of amoebiasis requires use of specific and sensitive tools such as specific antigen assays or polymerase-chain-reaction assays because microscopy cannot differentiate E. histolytica from E. dispar or E. moshikovskii, the later two being non-pathogenic. Nitroimidazoles, such as metronidazole and tinidazole remain the main treatment of choice for E. histolytica infection. To eliminate intestinal colonization of E. histolytica with subsequent recurrences or onward transmission, treatment of luminal agents, such as diloxanide furoate, paromomycin, or iodoquinol (diiodohydroxyquin) are needed.