Spatial and temporal dynamics of pathogenic Leptospira in surface waters from the urban slum environment. (1st March 2018)

• Record Type: Journal Article
• Authors: Casanovas-Massana, Arnau; Costa, Federico; Riediger, Irina N.; Cunha, Marcelo; de Oliveira, Daiana; Mota, Diogenes C.; Sousa, Erica; Querino, Vladimir A.; Nery, Nivisson; Reis, Mitermayer G.; Wunder, Elsio A.; Diggle, Peter J.; Ko, Albert I.
• Is Part Of: Water research. Volume 130(2018)
• Page Start: 176
• Page End: 184
• Publication Date: 2018-03-01
• Subjects: Leptospira -- Leptospirosis -- Surface water -- Public health -- Sewage -- Urban slum; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2017.11.068
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: 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. Graphical abstract: Highlights: Sewage and standing water are a source of pathogenic Leptospira in urban slums. Leptospira were ubiquitous in this setting, detected in 33% of sampled surface water. Pathogen concentrations were low (∼150 GEq/mL) in positive surface water samples. Seasonal leptospirosis risk is associated with increased pathogen detection in water. Prevention needs to account for the spatiotemporal dynamics of pathogenic Leptospira .