Malaria: Epidemiology - Reducing Malaria through Vector Control and Community Interventions
Comparison of long-lasting insecticidal nets versus long-lasting insecticidal nets in combination with indoor residual house spraying for malaria vector control: results of a cluster randomised
11/12/2012 8:00:00 AM
Philippa A. West
, Natacha Protopopoff
, Mark Rowland
, Alexandra Wright
, Zuhura Kivaju
, Matthew Kirby
, Franklin W. Mosha
, Immo Kleinschmidt
London School of Hygiene and Tropical Medicine, London, United Kingdom,
National Institute for Medical Research, Muheza, Tanzania, United Republic of,
Kilimanjaro Christian Medical College, Moshi, Tanzania, United Republic of
There is substantial evidence of the effectiveness of Insecticide Treated Nets (ITN) and Indoor Residual house Spraying (IRS) to protect against malaria. We conducted a cluster randomised controlled trial (CRT) in North-West Tanzania to investigate if there is an additional benefit to combining IRS and Long Lasting Insecticidal bed Nets (LLIN) compared to LLINs alone. A universal coverage campaign (UCC) aimed at providing one LLIN to each sleeping space in all 50 villages in the study area was carried out in 2011. Using restricted randomisation to ensure that the study arms were balanced on baseline factors including infection prevalence, 25 villages were allocated to the control arm (LLINs only) and 25 clusters to the intervention arm (LLIN+IRS). Interior walls of houses in the intervention arm were sprayed with the carbamate insecticide bendiocarb (Ficam, Bayer, Germany) in late 2011 to early 2012. Prevalence of Plasmodium falciparum (Pf) infections, clinical malaria and anaemia were compared between the two arms via two cross sectional household surveys 2 and 7 months post intervention. For each cluster approximately 90 children 6 months to 14 years old were randomly sampled. Monthly entomology surveys were conducted in 40 clusters using CDC light traps. Preliminary results from the first post-intervention survey show that prevalence of Pf infection in the intervention arm (IRS+LLIN) was 13.6% (95% CI = 8.4-21.4) compared to 23.5% (95% CI = 15.5-33.9) in control villages (LLINs alone), but the evidence for this difference was marginal (odds ratio = 0.51, 95% CI = 0.24-1.09; p-value=0.08). The range of cluster estimates were 0-48.4% and 0%-75% in the intervention and the control arms respectively. Anopheles densities were 82% (p=0.056), 98% (p<0.001) and 79% (p=0.21) lower in the intervention arm compared to the control arm in each of the three months following the intervention. Final results from both post intervention surveys will be presented. Early results from this CRT suggest that using IRS combined with LLINs is likely to be beneficial compared to using LLINs alone.
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