Environmental Detection of Pathogenic Leptospira DNA in Agricultural Ecosystems from a Mediterranean-Climate Region of Central Chile

Although pathogenic Leptospira DNA has been detected in water and soil from different climatic regions, information from Mediterranean-climate agricultural systems remains limited. This study characterized the environmental detection of pathogenic Leptospira DNA in water and soil samples from irrigated agroecosystems of central Chile, evaluating spatial and seasonal variation and associations with selected physicochemical variables. A total of 605 samples were collected from eight agricultural sites during spring 2019, summer 2020, and winter 2021. Samples were analyzed by real-time PCR targeting lipL32. Overall, 29.1% of samples were PCR-positive, and pathogenic Leptospira DNA was detected in all sites and seasons. Soil samples showed higher positivity than water samples (34.5% vs. 21.4%), and positivity was higher in summer (41.7%) than in spring (22.7%) or winter (19.3%). Water temperature and turbidity were the only physicochemical variables that differed between positive and negative samples, whereas the binomial generalized linear mixed model (GLMM) showed that season and sample type were associated with PCR positivity after accounting for site-level clustering. These results show that pathogenic Leptospira DNA can be widely detected in irrigated agricultural systems from a Mediterranean-climate region, suggesting that soil, seasonality, irrigation practices, and other site-level characteristics should be considered in future studies on the environmental ecology of pathogenic Leptospira.