title: Correlations between household occupancy and malaria vector biting risk in rural Tanzanian villages: implications for high-resolution spatial targeting of control interventions.
abstract: BACKGROUND
  Fine-scale targeting of interventions is increasingly important where epidemiological disease profiles depict high geographical stratifications. This study verified correlations between household biomass and mosquito house-entry using experimental hut studies, and then demonstrated how geographical foci of mosquito biting risk can be readily identified based on spatial distributions of household occupancies in villages.
  
  
  METHODS
  A controlled 4 × 4 Latin square experiment was conducted in rural Tanzania, in which no, one, three or six adult male volunteers slept under intact bed nets, in experimental huts. Mosquitoes entering the huts were caught using exit interception traps on eaves and windows. Separately, monthly mosquito collections were conducted in 96 randomly selected households in three villages using CDC light traps between March-2012 and November-2013. The number of people sleeping in the houses and other household and environmental characteristics were recorded. ArcGIS 10 (ESRI-USA) spatial analyst tool, Gi* Ord Statistic was used to analyse clustering of vector densities and household occupancy.
  
  
  RESULTS
  The densities of all mosquito genera increased in huts with one, three or six volunteers, relative to huts with no volunteers, and direct linear correlations within tested ranges (P < 0.001). Significant geographical clustering of indoor densities of malaria vectors, Anopheles arabiensis and Anopheles funestus, but not Culex or Mansonia species occurred in locations where households with highest occupancy were also most clustered (Gi* P ≤ 0.05, and Gi* Z-score ≥ 1.96).
  
  
  CONCLUSIONS
  This study demonstrates strong correlations between household occupancy and malaria vector densities in households, but also spatial correlations of these variables within and between villages in rural southeastern Tanzania. Fine-scale clustering of indoor densities of vectors within and between villages occurs in locations where houses with highest occupancy are also clustered. The study indicates potential for using household census data to preliminarily identify households with greatest Anopheles mosquito biting risk.
authors.affiliation: Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Morogoro, Tanzania. ekaindoa@ihi.or.tz.|Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK. ekaindoa@ihi.or.tz.|School of Public Health, University of the Witwatersrand, Johannesburg, South Africa. ekaindoa@ihi.or.tz.
authors.forename: Emmanuel W
authors.initials: EW
authors.lastname: Kaindoa
authors.affiliation: Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Morogoro, Tanzania.
authors.forename: Gustav
authors.initials: G
authors.lastname: Mkandawile
authors.affiliation: Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Morogoro, Tanzania.
authors.forename: Godfrey
authors.initials: G
authors.lastname: Ligamba
authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.
authors.forename: Louise A
authors.initials: LA
authors.lastname: Kelly-Hope
authors.affiliation: Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Morogoro, Tanzania.|School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Fredros O
authors.initials: FO
authors.lastname: Okumu
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000852:Anopheles / Q000502:physiology*; D003465:Culex / Q000502:physiology*; D005191:Family Characteristics; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007299:Insect Bites and Stings / Q000453:epidemiology*; D008137:Longitudinal Studies; D008288:Malaria / Q000517:prevention & control*; D008297:Male; D009032:Mosquito Control / Q000379:methods*; D012424:Rural Population; D013636:Tanzania; D055815:Young Adult
keywords: Hot spots; Household occupancy; Malaria; Mosquitoes; Targeting interventions