Seasonal shifts in the presence of pathogenic leptospires, Escherichia coli, and physicochemical properties in coastal rivers and streams of Puerto Rico.

Leptospirosis is an emerging zoonotic disease in the Caribbean region and the island of Puerto Rico. Information on the presence of pathogenic Leptospira in rivers and streams of Puerto Rico is currently lacking. This study aimed to evaluate seasonal shifts in the presence of pathogenic leptospires and the level of Escherichia coli from 32 coastal locations in Puerto Rico's dry and wet seasons. Physicochemical parameters (temperature, salinity, pH, and dissolved oxygen) were determined at each site. The temperature (25.8 °C) and pH (average 7.6) values were all within acceptable USEPA regulatory standards. Thirty-eight percent of the sites of the dry season and 28% of the wet season sites contained dissolved oxygen levels ≤4 mg L-1 , which is relatively low. In the dry season, 19 sites (59%) and 18 (56%) of the wet season sites had E. coli counts >410 most probable number (MPN) 100 ml-1 and would be considered unsafe for recreational use. The lipl32 gene quantitative polymerase chain reaction assay was used for the detection of pathogenic leptospires in the samples. Low concentrations of pathogenic leptospires (<60 genome copies 100 ml-1 ) at Camuy, Espíritu Santo, Río Guayanilla, Quebrada Majagual, and Río Fajardo were detected during the wet season. Pathogenic leptospires were detected (∼40 genome copies 100 ml-1 ) at only one site, Loíza, during the dry season. There was no predictable relationship between the physicochemical parameters, concentrations of E. coli, and the presence of pathogenic leptospires in water samples.