Abstract: Objective　To investigate the prevalence and risk factors of Blastocystis infections among primary school students in Jiangjin District, Chongqing City. Methods　A cross?sectional questionnaire survey was conducted among students sampled from a primary school in Jiangjin District, Chongqing City on April, 2018, and their stool samples were collected for microscopic examinations, in vitro culture and PCR assays to analyze the prevalence of Blastocystis infections and subtype of the parasite. In addition, the risk factors of Blastocystis infections among primary school students were identified using univariate analysis and multivariate logistic regression analysis. Results　A total of 466 primary students were surveyed, and the subjects had a mean age of (9.81±1.66) years and included 236 males (50.64%) and 230 females (49.36%). The prevalence of Blastocystis infections was 15.24% (71/466) among the study students, and there was no significance difference in the prevalence between male and female students (16.52% vs. 13.91%; [χ2] = 0.616, P = 0.433). In addition, there was a significant difference in the prevalence of Blastocystis infections among grade 1 (6.35%, 4/63), grade 2 (5.17%, 3/58), grade 3 (21.74%, 15/69), grade 4 (25.30%, 21/83), grade 5 (10.19%, 11/108) and grade 6 students (20.00%, 17/85) ([χ2] = 15.410，P = 0.009). There were four Blastocystis subtypes characterized (ST1, ST3, ST6 and ST7), in which ST6 was the most common subtype (45.07%, 32/71), followed by ST3 (25.35%, 18/71). Multivariate logistic regression analysis revealed that minority ethnicity [odds ratio (OR) = 4.259, 95% confidential interval (CI）: (1.161, 15.621)] and low maternal education level (primary school and below) [OR = 9.038, 95% CI: (1.125, 72.642)] were identified as risk factors of Blastocystis infection among primary school students in Jiangjin District, Chongqing City. Conclusions　There is a high prevalence of Blastocystis infections detected among primary school students in Jiangjin District, Chongqing City, and ST6 and ST3 are predominant subtypes. Minority ethnicity and low maternal education level (primary school and below) are risk factors for Blastocystis infections in primary school students.

Key words: Blastocystis sp., Subtype, Risk factor, Primary school student, Jiangjin District

摘要： 目的　了解重庆市江津区小学生芽囊原虫感染率及其危险因素。方法　2018年4月，采用横断面调查方法对重庆市江津区某小学在校学生进行问卷调查，并采集其粪便样本进行镜检、体外培养及PCR检测，以了解当地学生芽囊原虫感染情况及基因型分布。采用单因素分析和logistic回归分析对该校学生芽囊原虫感染危险因素进行分析。结果　 共调查466名小学生，平均年龄（9.81 ± 1.66）岁，男性236例 （50.64%）、女性230例（49.36%）。小学生芽囊原虫感染率为15.24%（71/466），其中男生感染率为16.52%（39/236）、女生为13.91%（32/230），差异无统计学意义（[χ2] = 0.616，P = 0.433）。1～5年级小学生芽囊原虫感染率分别为6.35%（4/63）、5.17%（3/58）、21.74%（15/69）、25.30%（21/83）、10.19%（11/108）和20.00%（17/85），不同年级小学生芽囊原虫感染率差异有统计学意义（[χ2] = 15.410，P = 0.009）。该校小学生感染的芽囊原虫基因型有4种（ST1、ST3、ST6和ST7）；其中ST6型最多，占45.07%（32/71）；其次是ST3型，占25.35%（18/71）。多因素logistic回归分析结果显示，少数民族[比值比（odds ratio，OR）= 4.259，95%可信区间（confidential interval，CI）：（1.161, 15.621）]和母亲小学及以下受教育程度 [OR = 9.038，95% CI：（1.125，72.642）]是小学生芽囊原虫感染的危险因素。结论　重庆市江津区小学生芽囊原虫感染率较高，感染的主要基因型为ST6和ST3，少数民族、母亲小学及以下受教育程度是该人群芽囊原虫感染的危险因素。 　

关键词: 芽囊原虫, 基因型, 危险因素, 小学生, 江津区