title: Mapping hotspots of malaria transmission from pre-existing hydrology, geology and geomorphology data in the pre-elimination context of Zanzibar, United Republic of Tanzania.
abstract: BACKGROUND
  Larval source management strategies can play an important role in malaria elimination programmes, especially for tackling outdoor biting species and for eliminating parasite and vector populations when they are most vulnerable during the dry season. Effective larval source management requires tools for identifying geographic foci of vector proliferation and malaria transmission where these efforts may be concentrated. Previous studies have relied on surface topographic wetness to indicate hydrological potential for vector breeding sites, but this is unsuitable for karst (limestone) landscapes such as Zanzibar where water flow, especially in the dry season, is subterranean and not controlled by surface topography.
  
  
  METHODS
  We examine the relationship between dry and wet season spatial patterns of diagnostic positivity rates of malaria infection amongst patients reporting to health facilities on Unguja, Zanzibar, with the physical geography of the island, including land cover, elevation, slope angle, hydrology, geology and geomorphology in order to identify transmission hot spots using Boosted Regression Trees (BRT) analysis.
  
  
  RESULTS
  The distribution of both wet and dry season malaria infection rates can be predicted using freely available static data, such as elevation and geology. Specifically, high infection rates in the central and southeast regions of the island coincide with outcrops of hard dense limestone which cause locally elevated water tables and the location of dolines (shallow depressions plugged with fine-grained material promoting the persistence of shallow water bodies).
  
  
  CONCLUSIONS
  This analysis provides a tractable tool for the identification of malaria hotspots which incorporates subterranean hydrology, which can be used to target larval source management strategies.
authors.affiliation: Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, UK. ajh13@aber.ac.uk.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hardy
authors.affiliation: Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, United Republic of Tanzania. zmageni@ihi.or.tz.
authors.forename: Zawadi
authors.initials: Z
authors.lastname: Mageni
authors.affiliation: Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland. stefan.dongus@unibas.ch.
authors.forename: Stefan
authors.initials: S
authors.lastname: Dongus
authors.affiliation: Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, United Republic of Tanzania. gkilleen@ihi.or.tz.|Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK. gkilleen@ihi.or.tz.
authors.forename: Gerry
authors.initials: G
authors.lastname: Killeen
authors.affiliation: Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, UK. mvm@aber.ac.uk.
authors.forename: Mark G
authors.initials: MG
authors.lastname: Macklin
authors.affiliation: Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, United Republic of Tanzania. smajambere@ihi.or.tz.|Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK. smajambere@ihi.or.tz.
authors.forename: Silas
authors.initials: S
authors.lastname: Majambare
authors.affiliation: Zanzibar Malaria Elimination Program, Zanzibar, United Republic of Tanzania. busudi@gmail.com.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Ali
authors.affiliation: Zanzibar Malaria Elimination Program, Zanzibar, United Republic of Tanzania. mmwinyi@hotmail.com.
authors.forename: Mwinyi
authors.initials: M
authors.lastname: Msellem
authors.affiliation: Zanzibar Malaria Elimination Program, Zanzibar, United Republic of Tanzania. mtash2@gmail.com.
authors.forename: Abdul-Wahiyd
authors.initials: AW
authors.lastname: Al-Mafazy
authors.affiliation: School of Geography, University of Leeds, Leeds, UK. M.W.Smith@leeds.ac.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Smith
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, UK. cjt@aber.ac.uk.
authors.forename: Chris
authors.initials: C
authors.lastname: Thomas
mesh_terms: D000818:Animals; D062305:Geographic Mapping; D005843:Geography; D005844:Geology; D006801:Humans; D062070:Hydrology; D007303:Insect Vectors / Q000254:growth & development*; D007814:Larva / Q000254:growth & development; D008288:Malaria / Q000453:epidemiology* / Q000635:transmission*; D011891:Rain; D012044:Regression Analysis; D012621:Seasons; D013636:Tanzania / Q000453:epidemiology