The association between leptospirosis with a number of abiotic factors, in particular rainfall, has been well documented for humans and domestic animals; however, no study has yet examined rainfall data as a predictor of leptospiral infections in non-domestic host populations critical to the maintenance of the pathogen in the environment. 

Using a large-scale dataset composed of 15,171 rats, mice, and mongooses collected over a period of 14 consecutive years, with 8 years of concurrent trapping across three Hawaiian islands, we performed logistic regression model analyses to estimate the association between Leptospira infection and rainfall at three spatial (rainfall gauge station, forecast area, island) and three temporal (trap month, season, year) levels. 

Leptospiral infection prevalence was significantly associated with rainfall on multiple temporal-spatial scales for each of the genera studied. Specifically, associations were found between rainfall gauge station and season, and between forecast area and trap month. 

Finding significant associations between an infectious disease and rainfall at small temporal and spatial scales is uncommon. We will discuss potential intrinsic and extrinsic factors that may be responsible for shaping the ecology of Leptospira in the Hawaiian islands.