Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, 60 College Street, New Haven, CT, USA.
Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, 60 College Street, New Haven, CT, USA; Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Rua Waldemar Falcão, 121, Salvador, Bahia, Brazil; Instituto de Saúde Coletiva, Universidade Federal da Bahia, Rua Basílio da Gama, s/n, Campus Universitário Canela, Salvador, Bahia, Brazil.
Water Res. 2018 Mar 1;130:176-184. doi: 10.1016/j.watres.2017.11.068. Epub 2017 Nov 30.
Leptospirosis has emerged as an important urban health problem as slum settlements have expanded worldwide. Yet the dynamics of the environmentally transmitted Leptospira pathogen has not been well characterized in these settings. We used a stratified dense sampling scheme to study the dynamics of Leptospira abundance in surface waters from a Brazilian urban slum community. We collected surface water samples during the dry, intermediate and rainy seasons within a seven-month period and quantified pathogenic Leptospira by quantitative PCR (qPCR). We used logistic and linear mixed models to identify factors that explained variation for the presence and concentration of Leptospira DNA. Among 335 sewage and 250 standing water samples, Leptospira DNA were detected in 36% and 34%, respectively. Among the 236 samples with positive results geometric mean Leptospira concentrations were 152 GEq/mL. The probability of finding Leptospira DNA was higher in sewage samples collected during the rainy season when increased leptospirosis incidence occurred, than during the dry season (47.2% vs 12.5%, respectively, p = 0.0002). There was a marked spatial and temporal heterogeneity in Leptospira DNA distribution, for which type of water, elevation, and time of day that samples were collected, in addition to season, were significant predictors. Together, these findings indicate that Leptospira are ubiquitous in the slum environment and that the water-related risk to which inhabitants are exposed is low. Seasonal increases in Leptospira presence may explain the timing of leptospirosis outbreaks. Effective prevention will need to consider the spatial and temporal dynamics of pathogenic Leptospira in surface waters to reduce the burden of the disease.
钩端螺旋体病已成为一个重要的城市健康问题，因为贫民窟的扩张已经在全球范围内蔓延。然而，在这些环境中，经环境传播的钩端螺旋体病原体的动态尚未得到很好的描述。我们使用分层密集采样方案来研究巴西城市贫民窟社区地表水的钩端螺旋体丰度的动态。我们在七个月的时间内收集了旱季、雨季和旱季的地表水样本，并通过定量 PCR(qPCR)定量了致病性钩端螺旋体。我们使用逻辑和线性混合模型来确定解释存在和浓度变化的因素。在 335 个污水和 250 个静止水样中，分别检测到 36%和 34%的钩端螺旋体 DNA。在 236 个阳性结果的样本中，钩端螺旋体浓度的几何平均值为 152 GEq/mL。在雨季（发生率较高）采集的污水样本中发现钩端螺旋体 DNA 的概率高于旱季（分别为 47.2%和 12.5%，p = 0.0002）。钩端螺旋体 DNA 分布具有明显的时空异质性，水样类型、海拔高度和采集时间，以及季节，都是显著的预测因子。这些发现表明，钩端螺旋体在贫民窟环境中无处不在，居民面临的与水有关的风险很低。钩端螺旋体存在的季节性增加可能解释了钩端螺旋体病爆发的时间。有效的预防措施需要考虑到地表水的致病性钩端螺旋体的时空动态，以降低疾病负担。
