United Graduate School of Agricultural Sciences, Iwate University, 18-8 Ueda 3-Chome, Morioka 020-8850, Japan.
Department of Food, Life and Environmental Sciences, Faculty of Agriculture, Yamagata University, 1-23 Wakaba-Machi, Tsuruoka 997-8555, Japan.
Int J Environ Res Public Health. 2021 Sep 11;18(18):9580. doi: 10.3390/ijerph18189580.
Disease outbreaks attributed to monsoon flood-induced pathogen exposure are frequently reported, especially in developing cities with poor sanitation. Contamination levels have been monitored in past studies, yet the sources, routes, and extents of contamination are not always clear. We evaluated pollution from municipal wastewater (MWW) discharge and investigated fecal contamination by () in three agricultural fields on the outskirts of Hue City, Vietnam. After concentration was determined in irrigation water (IRW), MWW, soil, vegetables (VEG), and manure, its dispersion from MWW was tracked using multilocus sequence typing (MLST) and phylogenetic analyses during the wet and dry seasons. IRW was severely contaminated; 94% of the samples were positive with exceeding the stipulated standards, while VEG contamination was very low in both seasons. The confirmed total number of isolates was comparable between the seasons; however, results from MLST and phylogenetic clustering revealed more links between the sites and samples to MWW during the wet season. The wet season had four mixed clusters of isolates from multiple locations and samples linked to MWW, while only one mixed cluster also linking MWW to IRW was observed during the dry season. The most prevalent sequence type (ST) complex 10 and two others (40 and 155) have been associated with disease outbreaks, while other STs have links to major pathotypes. Irrigation canals are significant routes for dispersion through direct links to the urban drainage-infested river. This study clarified the genotype of . in Hue city, and the numerous links between the samples and sites revealed MWW discharge as the source of contamination that was enhanced by flooding.
季风洪水引发的病原体暴露导致的疾病暴发经常有报道，尤其是在卫生条件较差的发展中城市。过去的研究已经监测了污染水平，但污染的来源、途径和程度并不总是清楚。我们评估了越南宁顺省 Hue 市郊区三个农业区的城市污水（MWW）排放和粪便污染。在确定灌溉水（IRW）、MWW、土壤、蔬菜（VEG）和粪便中的浓度后，使用多位点序列分型（MLST）和系统发育分析在雨季和旱季追踪 MWW 的粪便污染扩散。IRW 受到严重污染；94%的样本呈阳性，且超过规定标准，而 VEG 在两个季节的污染都非常低。两个季节的分离株总数相当；然而，MLST 和系统发育聚类结果表明，雨季期间，更多的地点和样本与 MWW 之间存在联系。雨季有四个来自多个地点和样本的混合 分离株群，与 MWW 有关，而旱季只观察到一个与 MWW 和 IRW 有关的混合群。最常见的序列型（ST）复合体 10 和另外两个（40 和 155）与疾病暴发有关，而其他 ST 与主要病原体有关。灌溉渠是通过直接与受城市排水污染的河流相连，将 扩散的重要途径。本研究阐明了 Hue 市的 基因型，并且样本和地点之间的大量联系表明，MWW 排放是污染的来源，洪水加剧了这种污染。
