芽囊原蟲屬（學名：Blastocystis）包含一些單細胞不等鞭毛類的寄生蟲，一般在各種動物的胃腸道內生活造成芽囊原蟲感染（blastocystosis），在人類、牲畜、鳥類、鼠類、爬行類、兩棲類、蟑螂體內都有分布[2]。此類生物對宿主選擇性不高，因此有多個（分類學上的）物種都可感染人類；按現有醫學分類習慣，這些物種都可稱作人芽囊原蟲（Blastocystis hominis）[3]。芽囊原蟲屬的分類地位曾多次變化，最初因外型與酵母菌相似、缺乏偽足以及不能移動等特色而被認為是一類酵母菌[4]，後來一度被歸為原生生物（孢子蟲綱，今屬頂複門）[5]，1996年的分子種系發生學研究將其歸為不等鞭毛類的一員[6][7]。
Quick Facts 芽囊原蟲屬, 科學分類 ...
芽囊原蟲屬
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| 芽囊原蟲 Blastocystis sp.
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科學分類 
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| 界：
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色藻界 Chromista
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芽囊原蟲綱 Blastocystae
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| 目：
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芽囊原蟲目 Blastocystida
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| 科：
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芽囊原蟲科 Blastocystidae
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| 屬：
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芽囊原蟲屬 Blastocystis
(Alexieff 1911) Brumpt 1912[1]
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芽囊原蟲可感染人類而導致芽囊原蟲病，此類生物感染人類甚多，在美國的感染率高達23%（2000年）。在開發中國家更高，尤其是塞內加爾河谷兒童全數受感染。[8][9][10]此蟲過去認為不致病（無症狀感染者甚多），但二十一世紀起開始發現其可導致腹瀉、疲勞等症狀。流行病學觀察認為此蟲可能引發腸易激症候群。[11]然而目前還缺乏對此蟲致病性的決定性證據（健康人士感染後發病）。
此蟲在人類中以糞口途徑傳播，主要是通過進食受糞便污染水、食物感染。[12]離自來水廠夠近，含氯充足的自來水不會導致感染。[13]同一個家庭中的成人基本不會互相傳播疾病，即使同居多年都還可能各自攜帶不同的芽囊原蟲。[14]
Alexeieff A. Sur la nature des formations dites "kystes de Trichomonas intestinalis". CR Soc Biol. 1911, 71: 296–298.
Brumpt E. Blastocystis hominis n. sp. et formes voisines. Bulletin of the Exotic Pathology Society. 1912, 5: 725–30.
El Safadi D, Gaayeb L, Meloni D, Cian A, Poirier P, Wawrzyniak I, Delbac F, Dabboussi F, Delhaes L, Seck M, Hamze M, Riveau G, Viscogliosi E. Children of Senegal River Basin show the highest prevalence of Blastocystis sp. ever observed worldwide. BMC Infect. Dis. March 2014, 14: 164. PMC 3987649 
. PMID 24666632. doi:10.1186/1471-2334-14-164. Amin OM. Seasonal prevalence of intestinal parasites in the United States during 2000 (PDF). Am. J. Trop. Med. Hyg. 2002, 66 (6): 799–803 [3 January 2016]. PMID 12224595. doi:10.4269/ajtmh.2002.66.799. （原始內容 (PDF)存檔於27 May 2020）. Parasitologic investigations of large patient populations are rarely conducted in the United States, where the illusion of freedom from parasitic infections still predominates. Such investigations are considerably more common in third-world countries where endemic parasitoses are more readily documented.1 In an attempt to address this problem we reported the results of routine examination of fecal specimens for parasites from 644 patients in the United States during the summer of 1996. ...
Prevalence. Nine hundred sixteen (32%) of 2,896 tested patients were infected with 18 species of intestinal parasites in the year 2000 (Table 1) in 48 states and the District of Columbia as follows ... Blastocystis hominis was the most frequently detected parasite in single and multiple infections, with Cryptosporidium parvum and Entamoeba histolytica/E. dispar ranking second and third, respectively.
Boorom KF, Smith H, Nimri L, Viscogliosi E, Spanakos G, Parkar U, Li LH, Zhou XN, Ok UZ, Leelayoova S, Jones MS. Oh my aching gut: irritable bowel syndrome, Blastocystis, and asymptomatic infection. Parasit Vectors. 2008, 1 (1): 40. PMC 2627840 . PMID 18937874. doi:10.1186/1756-3305-1-40. Blastocystis is now by far the most prevalent mono-infection in symptomatic patients in the United States [14] and was found 28.5 times more often than Giardia lamblia as a mono-infection in symptomatic patients in a 2000 study [14].
Figure 4: Prevalence of IBS and Blastocystosis by country
Basualdo J, Pezzani B, De Luca M, Córdoba A, Apezteguía M. Screening of the municipal water system of La Plata, Argentina, for human intestinal parasites. Int J Hyg Environ Health. 2000, 203 (2): 177–82. PMID 11109572. doi:10.1078/S1438-4639(04)70025-5.
