Is the Presence of Leptospira in the Environment Merely Random? an Epidemiological Explanation Based on Serial Analysis of Water Samples

Human leptospirosis cannot be investigated without studying zoonotic and environmental as-pects of the disease. The objectives of this study are to explore the abundance of Leptospira in dif-ferent climate zones of Sri Lanka and to describe the presence of Leptospira in same water source at different time points. First, water and soil samples were collected from whole-island, secondly, water sampling continued only in dry-zone, finally serial sampling of water from ten open wells was performed at five different time points. Quantitative PCR for water and metagenomic se-quencing for soil were used to detect Leptospira. In first component, 2 out of 12 water sites were positive and both are situated in wet-zone. Very small quantities of Genus Leptospira was detect-ed by metagenomic analysis of soil. Only 5 out of 26 samples were positive in the second compo-nent. Six, five, four, five, six wells were positive respectively in serial measurements of third component. All wells were positive at least one measurement while only one well was positive in all measurements. Closer to tank and higher distance from main road were significant risk fac-tors associated with well positivity. Presence of Leptospira seems not consistent indicating ran-dom abundance of Leptospira in natural environment.