title: Application of geographically-weighted regression analysis to assess risk factors for malaria hotspots in Keur Soce health and demographic surveillance site.
abstract: BACKGROUND
  In Senegal, considerable efforts have been made to reduce malaria morbidity and mortality during the last decade. This resulted in a marked decrease of malaria cases. With the decline of malaria cases, transmission has become sparse in most Senegalese health districts. This study investigated malaria hotspots in Keur Soce sites by using geographically-weighted regression. Because of the occurrence of hotspots, spatial modelling of malaria cases could have a considerable effect in disease surveillance.
  
  
  METHODS
  This study explored and analysed the spatial relationships between malaria occurrence and socio-economic and environmental factors in small communities in Keur Soce, Senegal, using 6 months passive surveillance. Geographically-weighted regression was used to explore the spatial variability of relationships between malaria incidence or persistence and the selected socio-economic, and human predictors. A model comparison of between ordinary least square and geographically-weighted regression was also explored. Vector dataset (spatial) of the study area by village levels and statistical data (non-spatial) on malaria confirmed cases, socio-economic status (bed net use), population data (size of the household) and environmental factors (temperature, rain fall) were used in this exploratory analysis. ArcMap 10.2 and Stata 11 were used to perform malaria hotspots analysis.
  
  
  RESULTS
  From Jun to December, a total of 408 confirmed malaria cases were notified. The explanatory variables-household size, housing materials, sleeping rooms, sheep and distance to breeding site returned significant t values of -0.25, 2.3, 4.39, 1.25 and 2.36, respectively. The OLS global model revealed that it explained about 70 % (adjusted R(2) = 0.70) of the variation in malaria occurrence with AIC = 756.23. The geographically-weighted regression of malaria hotspots resulted in coefficient intercept ranging from 1.89 to 6.22 with a median of 3.5. Large positive values are distributed mainly in the southeast of the district where hotspots are more accurate while low values are mainly found in the centre and in the north.
  
  
  CONCLUSIONS
  Geographically-weighted regression and OLS showed important risks factors of malaria hotspots in Keur Soce. The outputs of such models can be a useful tool to understand occurrence of malaria hotspots in Senegal. An understanding of geographical variation and determination of the core areas of the disease may provide an explanation regarding possible proximal and distal contributors to malaria elimination in Senegal.
authors.affiliation: Service Parasitologie, Université Cheikh Anta Diop, Dakar, Senegal. ndiath.mansour@gmail.com.
authors.forename: Mansour M
authors.initials: MM
authors.lastname: Ndiath
authors.affiliation: Service Parasitologie, Université Cheikh Anta Diop, Dakar, Senegal. badara.cisse@lshtm.ac.uk.|London School of Hygiene and Tropical Medicine, London, UK. badara.cisse@lshtm.ac.uk.
authors.forename: Badara
authors.initials: B
authors.lastname: Cisse
authors.affiliation: Service Parasitologie, Université Cheikh Anta Diop, Dakar, Senegal. jlndiaye@yahoo.com.
authors.forename: Jean Louis
authors.initials: JL
authors.lastname: Ndiaye
authors.affiliation: Service Parasitologie, Université Cheikh Anta Diop, Dakar, Senegal. jules.gomis@gmail.com.
authors.forename: Jules F
authors.initials: JF
authors.lastname: Gomis
authors.affiliation: Centre de Suivi Ecologique, CSE, Dakar, Senegal. ousmane.bathiery@cse.sn.
authors.forename: Ousmane
authors.initials: O
authors.lastname: Bathiery
authors.affiliation: Institut de santé et de développement, UCAD, Dakar, Senegal. adia@ised.sn.
authors.forename: Anta Tal
authors.initials: AT
authors.lastname: Dia
authors.affiliation: Service Parasitologie, Université Cheikh Anta Diop, Dakar, Senegal. ogaye@refer.sn.
authors.forename: Oumar
authors.initials: O
authors.lastname: Gaye
authors.affiliation: Service Parasitologie, Université Cheikh Anta Diop, Dakar, Senegal. bfaye67@yahoo.fr.|Unité Mixte Internationale « Environnement, Santé, Sociétés » (UMI3189 ESS), CNRS-UCAD-CNRST-USTTB-UGB, Dakar, Senegal. bfaye67@yahoo.fr.
authors.forename: Babacar
authors.initials: B
authors.lastname: Faye
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002648:Child; D002675:Child, Preschool; D003710:Demography; D004777:Environment; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008288:Malaria / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012675:Senegal / Q000453:epidemiology; D012959:Socioeconomic Factors; D000068916:Spatial Regression; D019371:Topography, Medical; D055815:Young Adult