Blanton Elizabeth, Wilhelm Natalie, O'Reilly Ciara, Muhonja Everline, Karoki Solomon, Ope Maurice, Langat Daniel, Omolo Jared, Wamola Newton, Oundo Joseph, Hoekstra Robert, Ayers Tracy, De Cock Kevin, Breiman Robert, Mintz Eric, Lantagne Daniele
Division of Foodborne, Waterborne, and Environmental Diseases, US Centers for Disease Control and Prevention, Atlanta, GA, USA.
Tufts University, Boston, USA and 200 College Avenue, Medford, MA 02155, USA E-mail:
J Water Health. 2015 Sep;13(3):714-25. doi: 10.2166/wh.2014.173.
Populations living in informal settlements with inadequate water and sanitation infrastructure are at risk of epidemic disease. In 2010, we conducted 398 household surveys in two informal settlements in Nairobi, Kenya with isolated cholera cases. We tested source and household water for free chlorine residual (FCR) and Escherichia coli in approximately 200 households. International guidelines are ≥0.5 mg/L FCR at source, ≥0.2 mg/L at household, and <1 E. coli/100 mL. In these two settlements, 82% and 38% of water sources met FCR guidelines; and 7% and 8% were contaminated with E. coli, respectively. In household stored water, 82% and 35% met FCR guidelines and 11% and 32% were contaminated with E. coli, respectively. Source water FCR≥0.5 mg/L (p=0.003) and reported purchase of a household water treatment product (p=0.002) were associated with increases in likelihood that household stored water had ≥0.2 mg/L FCR, which was associated with a lower likelihood of E. coli contamination (p<0.001). These results challenge the assumption that water quality in informal settlements is universally poor and the route of disease transmission, and highlight that providing centralized water with ≥0.5 mg/L FCR or (if not feasible) household water treatment technologies reduces the risk of waterborne cholera transmission in informal settlements.
生活在供水和卫生基础设施不完善的非正式定居点的人群面临着流行病的风险。2010年，我们在肯尼亚内罗毕的两个出现霍乱孤立病例的非正式定居点进行了398户家庭调查。我们对大约200户家庭的水源水和家庭用水进行了游离氯残留（FCR）和大肠杆菌检测。国际准则要求水源处FCR≥0.5毫克/升，家庭处≥0.2毫克/升，且大肠杆菌<1个/100毫升。在这两个定居点，分别有82%和38%的水源符合FCR准则；分别有7%和8%被大肠杆菌污染。在家庭储存水中，分别有82%和35%符合FCR准则，分别有11%和32%被大肠杆菌污染。水源水FCR≥0.5毫克/升（p=0.003）以及报告购买了家庭水处理产品（p=0.002）与家庭储存水FCR≥0.2毫克/升的可能性增加相关，而这又与大肠杆菌污染可能性较低相关（p<0.001）。这些结果挑战了非正式定居点水质普遍较差以及疾病传播途径的假设，并强调提供FCR≥0.5毫克/升的集中供水或（若不可行）家庭水处理技术可降低非正式定居点水源性霍乱传播的风险。
