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. 2011 Apr 29;6(4):e19205.
doi: 10.1371/journal.pone.0019205.

How much does malaria vector control quality matter: the epidemiological impact of holed nets and inadequate indoor residual spraying

Andrea M Rehman  1 , Mike Coleman, Christopher Schwabe, Giovanna Baltazar, Abrahan Matias, Irina Roncon Gomes, Lee Yellott, Cynthia Aragon, Gloria Nseng Nchama, Themba Mzilahowa, Mark Rowland, Immo Kleinschmidt
Affiliations

How much does malaria vector control quality matter: the epidemiological impact of holed nets and inadequate indoor residual spraying

Andrea M Rehman et al. PLoS One. .

Abstract

Background: Insecticide treated nets (ITN) and indoor residual spraying (IRS) are the two pillars of malaria vector control in Africa, but both interventions are beset by quality and coverage concerns. Data from three control programs were used to investigate the impact of: 1) the physical deterioration of ITNs, and 2) inadequate IRS spray coverage, on their respective protective effectiveness.

Methods: Malaria indicator surveys were carried out in 2009 and 2010 in Bioko Island, mainland Equatorial Guinea and Malawi to monitor infection with P. falciparum in children, mosquito net use, net condition and spray status of houses. Nets were classified by their condition. The association between infection and quality and coverage of interventions was investigated.

Results: There was reduced odds of infection with P. falciparum in children sleeping under ITNs that were intact (Odds ratio (OR): 0.65, 95% CI: 0.55-0.77 and OR: 0.81, 95% CI: 0.56-1.18 in Equatorial Guinea and in Malawi respectively), but the protective effect became less with increasingly worse condition of the net. There was evidence for a linear trend in infection per category increase in deterioration of nets. In Equatorial Guinea IRS offered protection to those in sprayed and unsprayed houses alike when neighbourhood spray coverage was high (≥80%) compared to those living in areas of low IRS coverage (<20%), regardless of whether the house they lived in was sprayed or not (adjusted OR = 0.54, 95% CI 0.33-0.89). ITNs provided only personal protection, offering no protection to non users. Although similar effects were seen in Malawi, the evidence was much weaker than in Equatorial Guinea.

Conclusions: Universal coverage strategies should consider policies for repair and replacement of holed nets and promote the care of nets by their owners. IRS programs should ensure high spray coverage since inadequate coverage gives little or no protection at all.

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Conflict of interest statement

Competing Interests: CS, GB, AM, IRG, LY and CA are employed by the international NGO Medical Care Development International (MCDI) which is supported by a consortium led by Marathon Oil Corporation and by the Global Fund to carry out malaria control in Equatorial Guinea. GNN is employed by the government of Equatorial Guinea. The London School of Hygiene and Tropical Medicine, amongst other international partners has a contract with MCDI for technical assistance. The commercial sources (see Financial Disclosure), which part-fund the Equatorial Guinea projects have no commercial interest in the findings made in this article. Private sector funding of one of the studies does not alter adherence to the PLoS ONE policies on sharing data and materials relevant to this article.

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