title: Spatial distribution of podoconiosis in relation to environmental factors in Ethiopia: a historical review.
abstract: BACKGROUND
  An up-to-date and reliable map of podoconiosis is needed to design geographically targeted and cost-effective intervention in Ethiopia. Identifying the ecological correlates of the distribution of podoconiosis is the first step for distribution and risk maps. The objective of this study was to investigate the spatial distribution and ecological correlates of podoconiosis using historical and contemporary survey data.
  
  
  METHODS
  Data on the observed prevalence of podoconiosis were abstracted from published and unpublished literature into a standardized database, according to strict inclusion and exclusion criteria. In total, 10 studies conducted between 1969 and 2012 were included, and data were available for 401,674 individuals older than 15 years of age from 229 locations. A range of high resolution environmental factors were investigated to determine their association with podoconiosis prevalence, using logistic regression.
  
  
  RESULTS
  The prevalence of podoconiosis in Ethiopia was estimated at 3.4% (95% CI 3.3%-3.4%) with marked regional variation. We identified significant associations between mean annual Land Surface Temperature (LST), mean annual precipitation, topography of the land and fine soil texture and high prevalence of podoconiosis. The derived maps indicate both widespread occurrence of podoconiosis and a marked variability in prevalence of podoconiosis, with prevalence typically highest at altitudes >1500 m above sea level (masl), with >1500 mm annual rainfall and mean annual LST of 19-21°C. No (or very little) podoconiosis occurred at altitudes <1225 masl, with annual rainfall <900 mm, and mean annual LST of >24°C.
  
  
  CONCLUSIONS
  Podoconiosis remains a public health problem in Ethiopia over considerable areas of the country, but exhibits marked geographical variation associated in part with key environmental factors. This is work in progress and the results presented here will be refined in future work.
authors.affiliation: Brighton and Sussex Medical School, Falmer, Brighton, United Kingdom. Kebededeka@yahoo.com
authors.forename: Kebede
authors.initials: K
authors.lastname: Deribe
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Brooker
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Pullan
authors.forename: Asrat
authors.initials: A
authors.lastname: Hailu
authors.forename: Fikre
authors.initials: F
authors.lastname: Enquselassie
authors.forename: Richard
authors.initials: R
authors.lastname: Reithinger
authors.forename: Melanie
authors.initials: M
authors.lastname: Newport
authors.forename: Gail
authors.initials: G
authors.lastname: Davey
mesh_terms: D004604:Elephantiasis / Q000453:epidemiology* / Q000209:etiology* / Q000266:history; D004777:Environment; D005002:Ethiopia / Q000453:epidemiology; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D015995:Prevalence; D062206:Spatial Analysis; D019371:Topography, Medical