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

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. 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. 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 (