[Prevalence and risk factors of Giardia lamblia infections among colorectal cancer patients in Henan Province].

To investigate the epidemiological characteristics and identify the risk factors of Giardia lamblia infections among patients with colorectal cancer in Henan Province.A cross-sectional study was performed for questionnaire surveys among colorectal cancer patients in Henan Cancer Hospital during the period from March to July, 2021. Patients' stool samples were collected, and the triosephosphate isomerase (tpi) gene of G. lamblia was amplified in stool samples using nested PCR assay to characterize the parasite genotype. Univariate analysis and multivariate logistic regression analyses were employed to identify the risk factors of G. lamblia infections among colorectal cancer patients.A total of 307 colorectal cancer patients were investigated, including 176 males (57.3%) and 131 females (42.7%). PCR assay detected 8.1% [95% confidential interval (CI): (0.056, 0.117)] prevalence of G. lamblia infections among the study subjects, and there was no significant difference in the prevalence between men [9.1%, 95% CI: (0.057, 0.143)] and women [6.9%, 95% CI: (0.037, 0.125)] (χ2 = 0.495, P = 0.482). In addition, there was no age-specific prevalence of G. lamblia infections among the participants (χ2 = 1.534, P = 0.675). Multivariate logistic regression analysis identified use of septic tanks [odds ratio (OR) = 3.336, 95% CI: (1.201, 9.267)], daily use of well water [OR = 3.042, 95% CI: (1.093, 8.465)] and raising livestock [OR = 3.740, 95% CI: (1.154, 12.121)] as risk factors of G. lamblia infections among colorectal cancer patients, and the prevalence of abdominal pain was significantly greater in colorectal cancer patients with G. lamblia infections than in those without infections (P = 0.017). Among the 25 patients with G. lamblia infections, assemblage A was characterized in 24 (96.0%) cases and assemblage B in one case (4.0%).The prevalence of G. lamblia is high among colorectal cancer patients in Henan Province, and assemblage A is the dominant genotype of G. lamblia. Use of septic tanks, daily use of well water and raising livestock are risk factors of G. lamblia infections among patients with colorectal cancer.［摘要］目的 了解河南省结直肠癌患者蓝氏贾第鞭毛虫感染特征并分析其危险因素。方法 2021 年 3—7 月, 采用横 断面调查法对河南省肿瘤医院结直肠癌患者进行问卷调查, 并收集其粪便样本, 采用巢式 PCR 法扩增蓝氏贾第鞭毛虫磷 酸丙糖异构酶 (tpi) 基因以确定感染虫种基因型。采用单因素分析和多因素 logistic 回归模型分析结直肠癌患者感染蓝氏 贾第鞭毛虫的危险因素。结果 共调查结直肠癌患者 307 例, 其中男性 176 例 (占 57.3%)、女性 131 例 (占 42.7%)。巢式 PCR 检测粪样基因组 DNA 发现, 蓝氏贾第鞭毛虫感染率为 8.1%[25/307, 95% 可信区间 (CI): (0.056, 0.117)], 其中男性感 染率为 9.1%[16/176, 95% CI: (0.057, 0.143)]、女性感染率为 6.9%[9/131, 95% CI: (0.037, 0.125)] (χ2 = 0.495, P = 0.482)。不同年龄组结直肠癌患者蓝氏贾第鞭毛虫感染率差异无统计学意义 (χ2 = 1.534, P = 0.675)。多因素分析发现, 使用粪池 [比值比 (OR) = 3.336, 95% CI: (1.201, 9.267)]、日常使用水井水 [OR = 3.042, 95% CI: (1.093, 8.465)] 及饲养家畜 [OR = 3.740, 95% CI: (1.154, 12.121)] 是结直肠癌患者感染蓝氏贾第鞭毛虫的危险因素。结直肠癌患者中, 蓝氏贾第鞭毛虫感 染者腹痛发生率显著高于非感染者 (P = 0.017)。25 例蓝氏贾第鞭毛虫感染者中, 24 例 (占 96.0%) 为聚集体 A 型感染、1 例 (占 4.0%) 为聚集体 B 型感染。结论 河南省结直肠癌患者蓝氏贾第鞭毛虫感染率相对较高, 感染的蓝氏贾第鞭毛 虫主要基因型为聚集体 A 型; 使用粪池、日常使用水井水及饲养家畜是结直肠癌患者感染蓝氏贾第鞭毛虫的危险 因素。.