Biodiversity and leptospirosis risk: A case of pathogen regulation?

Derne, Bonnie T.; Fearnley, Emily; Lau, Colleen L.; Paynter, Stuart; Weinstein, Philip

doi:10.1016/j.mehy.2011.05.009

Cited by 50 publications

(40 citation statements)

References 42 publications

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“…Varying environmental health hazards operate in different settings, and include climate, flooding, land use, urbanisation, poor sanitation (e.g. urban slums), international trade and travel, environmental degradation, and loss of biodiversity [2]–[11]. Accurate data on disease incidence and outbreaks are lacking in many parts of the world because of the combination of poor awareness of the disease, low clinical suspicion, varied clinical presentations leading to misdiagnosis, and the lack of laboratory facilities to confirm diagnoses [12].…”

Section: Introductionmentioning

confidence: 99%

Leptospirosis in American Samoa – Estimating and Mapping Risk Using Environmental Data

et al. 2012

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BackgroundThe recent emergence of leptospirosis has been linked to many environmental drivers of disease transmission. Accurate epidemiological data are lacking because of under-diagnosis, poor laboratory capacity, and inadequate surveillance. Predictive risk maps have been produced for many diseases to identify high-risk areas for infection and guide allocation of public health resources, and are particularly useful where disease surveillance is poor. To date, no predictive risk maps have been produced for leptospirosis. The objectives of this study were to estimate leptospirosis seroprevalence at geographic locations based on environmental factors, produce a predictive disease risk map for American Samoa, and assess the accuracy of the maps in predicting infection risk.Methodology and Principal FindingsData on seroprevalence and risk factors were obtained from a recent study of leptospirosis in American Samoa. Data on environmental variables were obtained from local sources, and included rainfall, altitude, vegetation, soil type, and location of backyard piggeries. Multivariable logistic regression was performed to investigate associations between seropositivity and risk factors. Using the multivariable models, seroprevalence at geographic locations was predicted based on environmental variables. Goodness of fit of models was measured using area under the curve of the receiver operating characteristic, and the percentage of cases correctly classified as seropositive. Environmental predictors of seroprevalence included living below median altitude of a village, in agricultural areas, on clay soil, and higher density of piggeries above the house. Models had acceptable goodness of fit, and correctly classified ∼84% of cases.Conclusions and SignificanceEnvironmental variables could be used to identify high-risk areas for leptospirosis. Environmental monitoring could potentially be a valuable strategy for leptospirosis control, and allow us to move from disease surveillance to environmental health hazard surveillance as a more cost-effective tool for directing public health interventions.

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Section: Introductionmentioning

confidence: 99%

Leptospirosis in American Samoa – Estimating and Mapping Risk Using Environmental Data

et al. 2012

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“…[1][2][3][4][5][6][7][8][9] The environmental determinants of disease transmission vary between places, and include climate change, extreme weather, land use, international trade, animal reservoirs, and farming practices. 4,10,11 It has become increasingly apparent that rainfall, cyclones, flooding, urbanization, and recreation are important emerging risk factors, 4,[12][13][14][15] that biodiversity might be protective, 16,17 and ecological changes can influence serovar emergence. 9 Spatial epidemiology has recently been used to explore the complex transmission dynamics driving leptospirosis emergence, particularly in relation to environmental hazards.…”

Section: Introductionmentioning

confidence: 99%

Leptospirosis in American Samoa 2010: Epidemiology, Environmental Drivers, and the Management of Emergence

Lau

Dobson²,

Smythe³

et al. 2012

The American Society of Tropical Medicine and Hygiene

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Abstract. Leptospirosis has recently been reported as an emerging disease worldwide, and a seroprevalence study was undertaken in American Samoa to better understand the drivers of transmission. Antibodies indicative of previous exposure to leptospirosis were found in 15.5% of 807 participants, predominantly against three serovars that were not previously known to occur in American Samoa. Questionnaires and geographic information systems data were used to assess behavioral factors and environmental determinants of disease transmission, and logistic regression was used to identify factors associated with infection. Many statistically significant factors were consistent with previous studies, but we also showed a significant association with living at lower altitudes (odds ratio [OR] ¼ 1.53, 95% confidence interval [CI]: 1.03-2.28), and having higher numbers of piggeries around the home (OR ¼ 2.63, 95% CI: 1.52-4.40). Our findings support a multifaceted approach to combating the emergence of leptospirosis, including modification of individual behavior, but importantly also managing the evolving environmental drivers of risk.

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“…Leptospirosis has recently been discussed as an emerging disease in many different contexts around the world [2,9], and different environmental and ecological drivers of disease transmission have been identified [10-12]. Disease outbreaks have been associated with flooding in many areas including India, Philippines, Thailand, New Caledonia, Hawaii, Guyana and Nicaragua [13-19].…”

Section: Introductionmentioning

confidence: 99%

Emergence of new leptospiral serovars in American Samoa - ascertainment or ecological change?

et al. 2012

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BackgroundLeptospirosis has recently been discussed as an emerging infectious disease in many contexts, including changes in environmental drivers of disease transmission and the emergence of serovars. In this paper, we report the epidemiology of leptospiral serovars from our study of human leptospirosis in American Samoa in 2010, present evidence of recent serovar emergence, and discuss the potential epidemiological and ecological implications of our findings.MethodsSerovar epidemiology from our leptospirosis seroprevalence study in 2010 was compared to findings from a study in 2004. The variation in geographic distribution of the three most common serovars was explored by mapping sero-positive participants to their place of residence using geographic information systems. The relationship between serovar distribution and ecological zones was examined using geo-referenced data on vegetation type and population distribution.ResultsHuman leptospirosis seroprevalence in American Samoa was 15.5% in 2010, with serological evidence that infection was caused by three predominant serovars (Hebdomadis, LT 751, and LT 1163). These serovars differed from those identified in an earlier study in 2004, and were not previously known to occur in American Samoa. In 2010, serovars also differed in geographic distribution, with variations in seroprevalence between islands and different ecological zones within the main island.ConclusionsOur findings might indicate artefactual emergence (where serovars were long established but previously undetected), but we believe the evidence is more in favour of true emergence (a result of ecological change). Possibilities include changes in interactions between humans and the environment; introduction of serovars through transport of animals; evolution in distribution and/or abundance of animal reservoirs; and environmental changes that favour transmission of particular serovars.Future research should explore the impact of ecological change on leptospirosis transmission dynamics and serovar emergence, and investigate how such new knowledge might better target environmental monitoring for disease control at a public health level.

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Biodiversity and leptospirosis risk: A case of pathogen regulation?

Cited by 50 publications

References 42 publications

Leptospirosis in American Samoa – Estimating and Mapping Risk Using Environmental Data

Leptospirosis in American Samoa – Estimating and Mapping Risk Using Environmental Data

Leptospirosis in American Samoa 2010: Epidemiology, Environmental Drivers, and the Management of Emergence

Emergence of new leptospiral serovars in American Samoa - ascertainment or ecological change?

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