School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin 300384, PR China; Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin 300384, PR China.
School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin 300384, PR China.
Water Res. 2018 Sep 15;141:46-56. doi: 10.1016/j.watres.2018.05.016. Epub 2018 May 10.
Cryptosporidium and Giardia are critical parasites in the etiology of diarrhea worldwide, and often cause waterborne outbreaks. The presence of Cryptosporidium and Giardia in recreational lakes was investigated with molecular characterization, and a comprehensive quantitative microbial risk assessment (QMRA) of protozoan infections was performed, considering multiple exposure pathways, differences in age, sex, and disease severity, and the genotypes of the protozoa. Forty-three (82.7%) and 51 (98.1%) water samples were positive for Cryptosporidium oocysts and Giardia cysts, respectively, with average counts of 3.65 oocysts/10 L and 12.58 cysts/10 L, respectively. Six Cryptosporidium species and three Giardia lamblia assemblages were confirmed with molecular analyses. The protozoan concentration was significantly associated with water turbidity, but not with the total coliform numbers. Swimming in the lakes entailed the highest incidence risk of 5.72 × 10 per person per year (pppy) (95% confidence interval (CI): 0.03-43.33 × 10) for Cryptosporidium and 4.04 × 10 pppy (95% CI: 0.01-32.66 × 10) for Giardia, whereas wading entailed the lowest risk (2.20 × 10 and 1.70 × 10 pppy, respectively). The annual burdens attributable to recreational-water-associated cryptosporidiosis and giardiasis were 3.44 (95% CI: 0.04-23.51) and 1.81 (95% CI: 0.01-12.96) disability-adjusted life years per 1,000,000 individuals per year, respectively. Children were more likely to have an individual disease burden than adults, and males were more likely than females. Sensitivity analysis highlighted the great importance of controlling the proportion of exposed individuals and reducing the frequency of exposure. The methodology and results of this study will allow us to better evaluate and reduce the burden of Cryptosporidium and/or Giardia infections associated with recreational water use in China and other countries.
隐孢子虫和贾第鞭毛虫是全球腹泻病因学中至关重要的寄生虫，常引发水源性暴发。本研究采用分子特征分析方法调查了休闲湖泊中隐孢子虫和贾第鞭毛虫的存在情况，并进行了综合定量微生物风险评估（QMRA），考虑了多种暴露途径、年龄、性别和疾病严重程度以及原生动物基因型的差异。结果显示，43 份（82.7%）和 51 份（98.1%）水样中分别检出隐孢子虫卵囊和贾第鞭毛虫包囊，平均含量分别为 3.65 个/10 L 和 12.58 个/10 L。分子分析证实存在 6 种隐孢子虫和 3 种蓝氏贾第鞭毛虫组合。原生动物浓度与水浊度显著相关，但与总大肠菌群数无关。在湖中游泳的个体感染风险最高，每年每人为 5.72×10 个人每年发病（pppy）（95%置信区间（CI）：0.03-43.33×10），感染隐孢子虫；而在湖中涉水的个体感染风险最低，每年每人为 2.20×10 和 1.70×10 pppy（95%CI：0.01-32.66×10），感染贾第鞭毛虫。每年因与休闲水相关的隐孢子虫病和贾第虫病而导致的疾病负担分别为 3.44（95%CI：0.04-23.51）和 1.81（95%CI：0.01-12.96）残疾调整生命年/每 100 万人每年。儿童的个体疾病负担比成年人更重，男性比女性更重。敏感性分析强调了控制暴露人群比例和减少暴露频率的重要性。本研究的方法和结果将有助于更好地评估和减少与中国和其他国家休闲用水相关的隐孢子虫和/或贾第鞭毛虫感染的疾病负担。
