title: Indoor residual spraying in combination with insecticide-treated nets compared to insecticide-treated nets alone for protection against malaria: a cluster randomised trial in Tanzania.
abstract: BACKGROUND
  Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) of houses provide effective malaria transmission control. There is conflicting evidence about whether it is more beneficial to provide both interventions in combination. A cluster randomised controlled trial was conducted to investigate whether the combination provides added protection compared to ITNs alone.
  
  
  RESULTS
  In northwest Tanzania, 50 clusters (village areas) were randomly allocated to ITNs only or ITNs and IRS. Dwellings in the ITN+IRS arm were sprayed with two rounds of bendiocarb in 2012. Plasmodium falciparum prevalence rate (PfPR) in children 0.5-14 y old (primary outcome) and anaemia in children <5 y old (secondary outcome) were compared between study arms using three cross-sectional household surveys in 2012. Entomological inoculation rate (secondary outcome) was compared between study arms. IRS coverage was approximately 90%. ITN use ranged from 36% to 50%. In intention-to-treat analysis, mean PfPR was 13% in the ITN+IRS arm and 26% in the ITN only arm, odds ratio = 0.43 (95% CI 0.19-0.97, n = 13,146). The strongest effect was observed in the peak transmission season, 6 mo after the first IRS. Subgroup analysis showed that ITN users were additionally protected if their houses were sprayed. Mean monthly entomological inoculation rate was non-significantly lower in the ITN+IRS arm than in the ITN only arm, rate ratio = 0.17 (95% CI 0.03-1.08).
  
  
  CONCLUSIONS
  This is the first randomised trial to our knowledge that reports significant added protection from combining IRS and ITNs compared to ITNs alone. The effect is likely to be attributable to IRS providing added protection to ITN users as well as compensating for inadequate ITN use. Policy makers should consider deploying IRS in combination with ITNs to control transmission if local ITN strategies on their own are insufficiently effective. Given the uncertain generalisability of these findings, it would be prudent for malaria control programmes to evaluate the cost-effectiveness of deploying the combination.
  
  
  BACKGROUND
  www.ClinicalTrials.gov NCT01697852 Please see later in the article for the Editors' Summary.
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Philippa A
authors.initials: PA
authors.lastname: West
authors.affiliation: Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Natacha
authors.initials: N
authors.lastname: Protopopoff
authors.affiliation: Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Wright
authors.affiliation: National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania.
authors.forename: Zuhura
authors.initials: Z
authors.lastname: Kivaju
authors.affiliation: Muleba District Medical Office, Department of Health, Muleba, Tanzania.
authors.forename: Robinson
authors.initials: R
authors.lastname: Tigererwa
authors.affiliation: Kilimanjaro Christian Medical College, Tumaini University, Moshi, Tanzania.
authors.forename: Franklin W
authors.initials: FW
authors.lastname: Mosha
authors.affiliation: National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania.
authors.forename: William
authors.initials: W
authors.lastname: Kisinza
authors.affiliation: Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Rowland
authors.affiliation: Medical Research Council Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Immo
authors.initials: I
authors.lastname: Kleinschmidt
mesh_terms: D000293:Adolescent; D000818:Animals; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D009033:Culicidae; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D057148:Insecticide-Treated Bednets / Q000592:standards*; D007306:Insecticides; D008288:Malaria / Q000453:epidemiology / Q000469:parasitology / Q000517:prevention & control*; D009032:Mosquito Control / Q000379:methods*; D048448:Phenylcarbamates; D010963:Plasmodium falciparum / Q000502:physiology; D015995:Prevalence; D012621:Seasons; D013636:Tanzania / Q000453:epidemiology
chemical_list: D007306:Insecticides; D048448:Phenylcarbamates; C007725:bendiocarb
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