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Effect of two different house screening interventions on exposure to malaria vectors and on anaemia in children in The Gambia: a randomised controlled trial.

Kirby, M.J and Ameh, D and Bottomley, C and Green, C and Jawara, M and Milligan, P.J and Snell, P.C and Conway, D.J and Lindsay, S.W (2009) 'Effect of two different house screening interventions on exposure to malaria vectors and on anaemia in children in The Gambia: a randomised controlled trial.', The lancet., 374 (9694). pp. 998-1009.


Background: House screening should protect people against malaria. We assessed whether two types of house screening—full screening of windows, doors, and closing eaves, or installation of screened ceilings—could reduce house entry of malaria vectors and frequency of anaemia in children in an area of seasonal malaria transmission. Methods: During 2006 and 2007, 500 occupied houses in and near Farafenni town in The Gambia, an area with low use of insecticide-treated bednets, were randomly assigned to receive full screening, screened ceilings, or no screening (control). Randomisation was done by computer-generated list, in permuted blocks of five houses in the ratio 2:2:1. Screening was not treated with insecticide. Exposure to mosquitoes indoors was assessed by fortnightly light trap collections during the transmission season. Primary endpoints included the number of female Anopheles gambiae sensu lato mosquitoes collected per trap per night. Secondary endpoints included frequency of anaemia (haemoglobin concentration <80 g/L) and parasitaemia at the end of the transmission season in children (aged 6 months to 10 years) who were living in the study houses. Analysis was by modified intention to treat (ITT), including all randomised houses for which there were some outcome data and all children from those houses who were sampled for haemoglobin and parasitaemia. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN51184253. Findings: 462 houses were included in the modified ITT analysis (full screening, n=188; screened ceilings, n=178; control, n=96). The mean number of A gambiae caught in houses without screening was 37·5 per trap per night (95% CI 31·6–43·3), compared with 15·2 (12·9–17·4) in houses with full screening (ratio of means 0·41, 95% CI 0·31–0·54; p<0·0001) and 19·1 (16·1–22·1) in houses with screened ceilings (ratio 0·53, 0·40–0·70; p<0·0001). 755 children completed the study, of whom 731 had complete clinical and covariate data and were used in the analysis of clinical outcomes. 30 (19%) of 158 children from control houses had anaemia, compared with 38 (12%) of 309 from houses with full screening (adjusted odds ratio [OR] 0·53, 95% CI 0·29–0·97; p=0·04), and 31 (12%) of 264 from houses with screened ceilings (OR 0·51, 0·27–0·96; p=0·04). Frequency of parasitaemia did not differ between intervention and control groups. Interpretation: House screening substantially reduced the number of mosquitoes inside houses and could contribute to prevention of anaemia in children.

Item Type:Article
Additional Information:Funding provided by the Medical Research Council.
Full text:(AM) Accepted Manuscript
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Publisher statement:NOTICE: this is the author’s version of a work that was accepted for publication in The Lancet. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in The Lancet, 374(9694), 19–25 September 2009, 10.1016/S0140-6736(09)60871-0
Date accepted:No date available
Date deposited:28 August 2015
Date of first online publication:2009
Date first made open access:No date available

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