Date of Award

Spring 5-7-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Science

First Advisor

Dr. Dave Bachoon

Second Advisor

Dr. C. Daniel Burt

Third Advisor

Dr. David Weese

Abstract

Leptospirosis, caused by pathogenic Leptospira, is endemic to tropical regions. Leptospira is released into the environment through the secretion of urine from animals, making it easily transmissible through water sources. The estuarian environment surrounding the area of San Juan, Puerto Rico and its high density of urban development creates ideal conditions for transmission of Leptospirosis. The goal of this study was to determine the presence of Leptospira in these surface waters and use Microbial Source Tracking (MST) to identify the possible source of pathogenic Leptospira. Eighty-seven water samples were collected during the dry (44) and wet (43) seasons. Phosphorus and nitrogen levels were determined using standard USEPA methods. The level of Leptospira interrogans was determined using quantitative polymerase chain reaction (qPCR) targeting the Lipl32 gene. Human (HF183), dog (BacCan-UCD), and horse (HoF597) MST assays were performed to determine the likely sources of fecal contamination at each site. Total phosphorous and total nitrogen exceeded USEPA safety guidelines in multiple locations. Leptospira interrogans was detected in 32% of samples collected in the dry season and was not detected in the wet season. There was a positive correlation (r =0.89) between the presence of L. interrogans and human fecal bacterial MST marker (HF183). The MST also indicated a positive correlation between horse fecal contamination and total phosphorus and total nitrogen. The correlation between L. interrogans gene copies and MST makers warrants further examination of the water quality in the estuaries of San Juan, Puerto Rico due to the possible public health implications.

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