Limits...
Mapping and Modelling the Geographical Distribution and Environmental Limits of Podoconiosis in Ethiopia.

Deribe K, Cano J, Newport MJ, Golding N, Pullan RL, Sime H, Gebretsadik A, Assefa A, Kebede A, Hailu A, Rebollo MP, Shafi O, Bockarie MJ, Aseffa A, Hay SI, Reithinger R, Enquselassie F, Davey G, Brooker SJ - PLoS Negl Trop Dis (2015)

Bottom Line: BRT modelling indicated that the probability of podoconiosis occurrence increased with increasing altitude, precipitation and silt fraction of soil and decreased with population density and clay content.The resultant maps can be used to guide programme planning and implementation and estimate disease burden in Ethiopia.This work provides a framework with which the geographical limits of podoconiosis could be delineated at a continental scale.

View Article: PubMed Central - PubMed

Affiliation: Brighton and Sussex Medical School, Falmer, Brighton, United Kingdom; School of Public Health, Addis Ababa University, Addis Ababa, Ethiopia.

ABSTRACT

Background: Ethiopia is assumed to have the highest burden of podoconiosis globally, but the geographical distribution and environmental limits and correlates are yet to be fully investigated. In this paper we use data from a nationwide survey to address these issues.

Methodology: Our analyses are based on data arising from the integrated mapping of podoconiosis and lymphatic filariasis (LF) conducted in 2013, supplemented by data from an earlier mapping of LF in western Ethiopia in 2008-2010. The integrated mapping used woreda (district) health offices' reports of podoconiosis and LF to guide selection of survey sites. A suite of environmental and climatic data and boosted regression tree (BRT) modelling was used to investigate environmental limits and predict the probability of podoconiosis occurrence.

Principal findings: Data were available for 141,238 individuals from 1,442 communities in 775 districts from all nine regional states and two city administrations of Ethiopia. In 41.9% of surveyed districts no cases of podoconiosis were identified, with all districts in Affar, Dire Dawa, Somali and Gambella regional states lacking the disease. The disease was most common, with lymphoedema positivity rate exceeding 5%, in the central highlands of Ethiopia, in Amhara, Oromia and Southern Nations, Nationalities and Peoples regional states. BRT modelling indicated that the probability of podoconiosis occurrence increased with increasing altitude, precipitation and silt fraction of soil and decreased with population density and clay content. Based on the BRT model, we estimate that in 2010, 34.9 (95% confidence interval [CI]: 20.2-51.7) million people (i.e. 43.8%; 95% CI: 25.3-64.8% of Ethiopia's national population) lived in areas environmentally suitable for the occurrence of podoconiosis.

Conclusions: Podoconiosis is more widespread in Ethiopia than previously estimated, but occurs in distinct geographical regions that are tied to identifiable environmental factors. The resultant maps can be used to guide programme planning and implementation and estimate disease burden in Ethiopia. This work provides a framework with which the geographical limits of podoconiosis could be delineated at a continental scale.

No MeSH data available.


Related in: MedlinePlus

Map of Ethiopia with regional boundary (A); geographical distribution of podoconiosis in 1,442 communities in 775 districts from all regions of Ethiopia (B); district level distribution of podoconiosis in 775 districts of Ethiopia(C, D).
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pntd.0003946.g001: Map of Ethiopia with regional boundary (A); geographical distribution of podoconiosis in 1,442 communities in 775 districts from all regions of Ethiopia (B); district level distribution of podoconiosis in 775 districts of Ethiopia(C, D).

Mentions: Ethiopia is located in the Horn of Africa. The total population in 2013 is estimated to be 86.6 million [16,17], with the majority of the population living in rural areas. Ethiopia has a federal system of administration with nine regional states and two city administration councils (Fig 1A) [18]. The country has three broad ecologic zones, based on topography: the “kola” or hot lowlands, the “weyna dega” or midland and the “dega” or the cool temperate highlands[19]. Altitudinal variation in temperature gives rise to a variety of vegetation types and suitability of land for agriculture [16].


Mapping and Modelling the Geographical Distribution and Environmental Limits of Podoconiosis in Ethiopia.

Deribe K, Cano J, Newport MJ, Golding N, Pullan RL, Sime H, Gebretsadik A, Assefa A, Kebede A, Hailu A, Rebollo MP, Shafi O, Bockarie MJ, Aseffa A, Hay SI, Reithinger R, Enquselassie F, Davey G, Brooker SJ - PLoS Negl Trop Dis (2015)

Map of Ethiopia with regional boundary (A); geographical distribution of podoconiosis in 1,442 communities in 775 districts from all regions of Ethiopia (B); district level distribution of podoconiosis in 775 districts of Ethiopia(C, D).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519246&req=5

pntd.0003946.g001: Map of Ethiopia with regional boundary (A); geographical distribution of podoconiosis in 1,442 communities in 775 districts from all regions of Ethiopia (B); district level distribution of podoconiosis in 775 districts of Ethiopia(C, D).
Mentions: Ethiopia is located in the Horn of Africa. The total population in 2013 is estimated to be 86.6 million [16,17], with the majority of the population living in rural areas. Ethiopia has a federal system of administration with nine regional states and two city administration councils (Fig 1A) [18]. The country has three broad ecologic zones, based on topography: the “kola” or hot lowlands, the “weyna dega” or midland and the “dega” or the cool temperate highlands[19]. Altitudinal variation in temperature gives rise to a variety of vegetation types and suitability of land for agriculture [16].

Bottom Line: BRT modelling indicated that the probability of podoconiosis occurrence increased with increasing altitude, precipitation and silt fraction of soil and decreased with population density and clay content.The resultant maps can be used to guide programme planning and implementation and estimate disease burden in Ethiopia.This work provides a framework with which the geographical limits of podoconiosis could be delineated at a continental scale.

View Article: PubMed Central - PubMed

Affiliation: Brighton and Sussex Medical School, Falmer, Brighton, United Kingdom; School of Public Health, Addis Ababa University, Addis Ababa, Ethiopia.

ABSTRACT

Background: Ethiopia is assumed to have the highest burden of podoconiosis globally, but the geographical distribution and environmental limits and correlates are yet to be fully investigated. In this paper we use data from a nationwide survey to address these issues.

Methodology: Our analyses are based on data arising from the integrated mapping of podoconiosis and lymphatic filariasis (LF) conducted in 2013, supplemented by data from an earlier mapping of LF in western Ethiopia in 2008-2010. The integrated mapping used woreda (district) health offices' reports of podoconiosis and LF to guide selection of survey sites. A suite of environmental and climatic data and boosted regression tree (BRT) modelling was used to investigate environmental limits and predict the probability of podoconiosis occurrence.

Principal findings: Data were available for 141,238 individuals from 1,442 communities in 775 districts from all nine regional states and two city administrations of Ethiopia. In 41.9% of surveyed districts no cases of podoconiosis were identified, with all districts in Affar, Dire Dawa, Somali and Gambella regional states lacking the disease. The disease was most common, with lymphoedema positivity rate exceeding 5%, in the central highlands of Ethiopia, in Amhara, Oromia and Southern Nations, Nationalities and Peoples regional states. BRT modelling indicated that the probability of podoconiosis occurrence increased with increasing altitude, precipitation and silt fraction of soil and decreased with population density and clay content. Based on the BRT model, we estimate that in 2010, 34.9 (95% confidence interval [CI]: 20.2-51.7) million people (i.e. 43.8%; 95% CI: 25.3-64.8% of Ethiopia's national population) lived in areas environmentally suitable for the occurrence of podoconiosis.

Conclusions: Podoconiosis is more widespread in Ethiopia than previously estimated, but occurs in distinct geographical regions that are tied to identifiable environmental factors. The resultant maps can be used to guide programme planning and implementation and estimate disease burden in Ethiopia. This work provides a framework with which the geographical limits of podoconiosis could be delineated at a continental scale.

No MeSH data available.


Related in: MedlinePlus