芽囊原虫属（学名：Blastocystis）包含一些单细胞不等鞭毛类的寄生虫，一般在各种动物的胃肠道内生活造成芽囊原虫感染（blastocystosis），在人类、牲畜、鸟类、鼠类、爬行类、两栖类、蟑螂体内都有分布[2]。此类生物对宿主选择性不高，因此有多个（分类学上的）物种都可感染人类；按现有医学分类习惯，这些物种都可称作人芽囊原虫（Blastocystis hominis）[3]。芽囊原虫属的分类地位曾多次变化，最初因外型与酵母菌相似、缺乏伪足以及不能移动等特色而被认为是一类酵母菌[4]，后来一度被归为原生生物（孢子虫纲，今属顶复门）[5]，1996年的分子种系发生学研究将其归为不等鞭毛类的一员[6][7]。
Quick Facts 芽囊原虫属, 科学分类 ...
芽囊原虫属
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| 芽囊原虫 Blastocystis sp.
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科学分类 
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| 界：
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色藻界 Chromista
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| 纲：
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芽囊原虫纲 Blastocystae
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| 目：
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芽囊原虫目 Blastocystida
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| 科：
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芽囊原虫科 Blastocystidae
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| 属：
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芽囊原虫属 Blastocystis
(Alexieff 1911) Brumpt 1912[1]
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芽囊原虫可感染人类而导致芽囊原虫病，此类生物感染人类甚多，在美国的感染率高达23%（2000年）。在发展中国家更高，尤其是塞内加尔河谷儿童全数受感染。[8][9][10]此虫过去认为不致病（无症状感染者甚多），但二十一世纪起开始发现其可导致腹泻、疲劳等症状。流行病学观察认为此虫可能引发肠易激综合征。[11]然而目前还缺乏对此虫致病性的决定性证据（健康人士感染后发病）。
此虫在人类中以粪口途径传播，主要是通过进食受粪便污染水、食物感染。[12]离自来水厂够近，含氯充足的自来水不会导致感染。[13]同一个家庭中的成人基本不会互相传播疾病，即使同居多年都还可能各自携带不同的芽囊原虫。[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. （原始内容 (PDF)存档于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.
