Hydrology and public health: linking human leptospirosis and local hydrological dynamics in Trinidad, West Indies

Maria Cecilia Vega-Corredor,Jacob Opadeyi

doi:10.1186/2194-6434-1-3

Maria Cecilia Vega-Corredor, Jacob Opadeyi

Open Access

https://doi.org/10.1186/2194-6434-1-3

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Journal: Earth Perspectives	Publication Date: Feb 12, 2014
Citations: 36	License type: cc-by

Affiliation: University of the West Indies

Abstract

Abstract Background Human leptospirosis is currently one of the most widespread bacterial zoonoses and is the only epidemic-prone infection that can be transmitted directly from contaminated water. Transmission in humans is caused by direct or indirect contact with contaminated water, soil or infected urine, blood or tissue of carrier animals. Initial symptoms are similar with those suffered during influenza, dengue or viral hepatitis. As the disease progresses, internal organs can be compromised causing severe hemorrhages, organ failure and, potentially, death. Human leptospirosis is a growing global public health problem although, in endemic areas, it is considered a neglected disease. Hydrological factors, including rainfall and floods, have been frequently related to human leptospirosis. In the Caribbean, leptospirosis is endemic and it is a disease under surveillance. Based on confirmed cases, in Trinidad & Tobago the average annual incidence of human leptospirosis ranges between 1.78 to 1.84 cases per 100,000 population. Methods In this paper, we used Geographical Information System (GIS) analysis and Geographically Weighted Poisson Regression (GWPR) for the development of ecological models, to assess the spatial variability in the relationships between local hydrological factors and human leptospirosis occurrence at the community level on the island of Trinidad. Five explanatory covariates were developed for the analysis: rainfall, river drainage density, proportion of soil with free drainage, proportion of soil with imperfect/impeded drainage, and a topographic wetness index. Results The GWPR model presented an improvement (AICc = 392.46; deviance = 583.36) over the Global regression model (AICc = 595.52; deviance = 381.78), indicating spatial variability in the relationship of human leptospirosis and hydrological factors. Pseudo t-values of rainfall, imperfect/impeded drainage soil and the topographic wetness index showed high values (|t| >1.96) indicating that local relationships with leptospirosis occurrence may be significant. Conclusion Results suggest that rainfall, imperfect/impeded drainage soil and topographic wetness index influence the local dynamics of human leptospirosis.

Highlights

Human leptospirosis is currently one of the most widespread bacterial zoonoses and is the only epidemic-prone infection that can be transmitted directly from contaminated water
Following previous research which has linked leptospirosis with hydrological events such as floods and heavy rainfall e.g. (Lau et al 2010b; Barcellos & Sabroza 2001; Gaynor et al 2007; Dechet et al 2012; Amilasan et al 2009), we present a multidisciplinary approach towards the quantitative analysis, assessment, modeling and mapping of the risk of leptospirosis in Trinidad at the community level, as it relates to hydrological factors
We explored the existence of spatial variation in human leptospirosis patterns and the existence of spatial heterogeneity in its relationship with local hydrological factors

Summary

Introduction

Human leptospirosis is currently one of the most widespread bacterial zoonoses and is the only epidemic-prone infection that can be transmitted directly from contaminated water. Human leptospirosis is a waterborne disease caused by spirochetes of the genus Leptospira It is considered the most common widespread bacterial zoonosis and a growing worldwide public health problem (Adler & de la Peña Monctezuma 2010; Levett 2001). Pathogenic leptospires are transmitted to humans by direct or indirect contact with infected urine, blood or tissue of carrier animals or urine-contaminated water, soil or food (Bharti et al 2003; World Health Organization 2003; Caribbean Epidemiology Center 1999). Leptospirosis symptoms can be similar to those caused by flu but, as the disease progresses, internal organs can be compromised causing severe hemorrhages (e.g.Weil’s disease), organ failure and, potentially, death (Vinetz et al 2005)

Methods

Results

Conclusion