Date of Award

January 2016

Document Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Albert I. Ko

Abstract

Introduction: Leptospirosis is an important cause of morbidity and mortality in Puerto Rico, but the full burden remains unknown due to underreporting and misdiagnosis as dengue fever.

Methods: A cross-sectional study paired with rodent trapping was carried out to determine the prevalence and risk factors for prior Leptospira infection in an urban community within San Juan, Puerto Rico. A mixed effect model was built to test for risk factors while controlling for grouping effects across neighborhood blocks.

Results: Among 202 human individuals enrolled, 55 (27.3%, 95% CI: 20.9-33.3%) had Leptospira agglutinating antibodies indicative of previous exposure to the bacteria. MLST testing of rodent samples indicated that L. borgpetersenii Ballum and L. interrogans Icterohaemorrhagiae are circulating among rodents in the study area. L. borgpetersenii Ballum was also isolated from the kidney of a rodent and showed agglutination against sera from 16 (7.9%) of humans enrolled, indicating that this serogroup is actively circulating among humans and rodents in this community. Living farther away from the Caño Martin Peña canal was associated with decreased risk of leptospire infection, with each meter of distance from the canal associated with an 0.6% decrease in risk of infection (OR:0.994, 95%CI: 0.990 – 0.998) and reported occurrence of household flooding was associated with lower likelihood of infection with leptospires (OR: 0.12, 95% CI: 0.04 – 0.37).

Conclusion: While leptospirosis is often associated with work-related exposures or densely packed urban slum communities, these results suggest that household-related exposures are an important factor in leptospire transmission in low-income urban non-slum communities. This study was a unique opportunity to identify a strain of a zoonotic disease circulating within both rodents and humans in a community facing a variety of environmental risk factors. This confirmation that leptospires are actively circulating in this community could lead to improved diagnostic awareness among healthcare providers and improved patient outcomes for this treatable disease.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 05/06/2018

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