Modelling environmental factors correlated with podoconiosis
Modelling environmental factors correlated with podoconiosis
The precise trigger of podoconiosis endemic non-filarial elephantiasis of the lower legs is unknown. Epidemiological and ecological studies have linked the disease with barefoot exposure to red clay soils of volcanic origin. Histopathology investigations have demonstrated silicon, aluminium, magnesium and iron in the lower limb lymph node macrophages of both patients and non-patients living barefoot on these clays. We studied the spatial variation (variations across an area) in podoconiosis prevalence and the associated environmental factors with the goal of better understanding the pathogenesis of podoconiosis.
Methods
Fieldwork was conducted from June 2011 to February 2013 in 12 kebeles (administrative units) in northern Ethiopia. Geo-located prevalence data and soil samples were collected and analysed along with secondary geological, topographic, meteorological and elevation data. Soil data were analysed for chemical composition, mineralogy and particle size; and interpolated to provide spatially continuous information. Exploratory, spatial, univariate and multivariate regression analyses of podoconiosis prevalence were conducted in relation to primary (soil) and secondary (elevation, precipitation, and geology) covariates.
Results
Podoconiosis distribution showed spatial correlation with variation in elevation and precipitation. Exploratory analysis identified that phyllosilicate minerals, particularly of the clay (smectite and kaolinite) and mica groups, quartz (crystalline silica), iron oxide, and zirconium were associated with podoconiosis prevalence. The final multivariate model showed that smectite (RR = 2.76, 95% CI: 1.35, 5.73; p = 0.007), quartz (RR = 1.16, 95% CI: 1.06, 1.26; p = 0.001) and mica (RR = 1.09, 95% CI: 1.05, 1.13; p < 0.001) had positive associations with podoconiosis prevalence.
Conclusions
Smectite, mica and quartz content of the soil was associated with podoconiosis prevalence. Together with previous work indicating that these minerals may influence water absorption, potentiate infection and be toxic to human cells, the present findings suggest that these particles may play a role in the pathogenesis of podoconiosis and acute adenolymphangitis, a common cause of morbidity in podoconiosis patients.
Molla, Yordanos
5d9a30e1-c3d2-45d8-9bf8-44c3b326a644
Wardrop, Nicola A.
8f3a8171-0727-4375-bc68-10e7d616e176
Le Blond, Jennifer
8e5b009e-2e8e-413f-a8d6-e2c664529c0f
Baxter, Peter
0e58b63b-ba61-44de-8ee3-1714d86a8134
Newport, Melanie
ad70a16a-6d64-4a0d-9fb1-5951b0e7c6be
Atkinson, Peter M.
96e96579-56fe-424d-a21c-17b6eed13b0b
Davey, Gail
0ecc5cff-ed5a-4184-b555-bdd97ff91860
2014
Molla, Yordanos
5d9a30e1-c3d2-45d8-9bf8-44c3b326a644
Wardrop, Nicola A.
8f3a8171-0727-4375-bc68-10e7d616e176
Le Blond, Jennifer
8e5b009e-2e8e-413f-a8d6-e2c664529c0f
Baxter, Peter
0e58b63b-ba61-44de-8ee3-1714d86a8134
Newport, Melanie
ad70a16a-6d64-4a0d-9fb1-5951b0e7c6be
Atkinson, Peter M.
96e96579-56fe-424d-a21c-17b6eed13b0b
Davey, Gail
0ecc5cff-ed5a-4184-b555-bdd97ff91860
Molla, Yordanos, Wardrop, Nicola A., Le Blond, Jennifer, Baxter, Peter, Newport, Melanie, Atkinson, Peter M. and Davey, Gail
(2014)
Modelling environmental factors correlated with podoconiosis.
International Journal of Health Geographics, 13 (24).
(doi:10.1186/1476-072X-13-24).
Abstract
The precise trigger of podoconiosis endemic non-filarial elephantiasis of the lower legs is unknown. Epidemiological and ecological studies have linked the disease with barefoot exposure to red clay soils of volcanic origin. Histopathology investigations have demonstrated silicon, aluminium, magnesium and iron in the lower limb lymph node macrophages of both patients and non-patients living barefoot on these clays. We studied the spatial variation (variations across an area) in podoconiosis prevalence and the associated environmental factors with the goal of better understanding the pathogenesis of podoconiosis.
Methods
Fieldwork was conducted from June 2011 to February 2013 in 12 kebeles (administrative units) in northern Ethiopia. Geo-located prevalence data and soil samples were collected and analysed along with secondary geological, topographic, meteorological and elevation data. Soil data were analysed for chemical composition, mineralogy and particle size; and interpolated to provide spatially continuous information. Exploratory, spatial, univariate and multivariate regression analyses of podoconiosis prevalence were conducted in relation to primary (soil) and secondary (elevation, precipitation, and geology) covariates.
Results
Podoconiosis distribution showed spatial correlation with variation in elevation and precipitation. Exploratory analysis identified that phyllosilicate minerals, particularly of the clay (smectite and kaolinite) and mica groups, quartz (crystalline silica), iron oxide, and zirconium were associated with podoconiosis prevalence. The final multivariate model showed that smectite (RR = 2.76, 95% CI: 1.35, 5.73; p = 0.007), quartz (RR = 1.16, 95% CI: 1.06, 1.26; p = 0.001) and mica (RR = 1.09, 95% CI: 1.05, 1.13; p < 0.001) had positive associations with podoconiosis prevalence.
Conclusions
Smectite, mica and quartz content of the soil was associated with podoconiosis prevalence. Together with previous work indicating that these minerals may influence water absorption, potentiate infection and be toxic to human cells, the present findings suggest that these particles may play a role in the pathogenesis of podoconiosis and acute adenolymphangitis, a common cause of morbidity in podoconiosis patients.
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Published date: 2014
Organisations:
Population, Health & Wellbeing (PHeW)
Identifiers
Local EPrints ID: 366291
URI: http://eprints.soton.ac.uk/id/eprint/366291
ISSN: 1476-072X
PURE UUID: 374094f8-1a17-4fa0-b692-f0f0baec909e
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Date deposited: 26 Jun 2014 16:14
Last modified: 15 Mar 2024 02:47
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Contributors
Author:
Yordanos Molla
Author:
Jennifer Le Blond
Author:
Peter Baxter
Author:
Melanie Newport
Author:
Peter M. Atkinson
Author:
Gail Davey
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