Long-lasting insecticide-treated nets combined or not with in-2 door residual spraying, may not be sufficient to eliminate ma-3 laria: a case-control study, Benin, West Africa

Abstract

In sub-Saharan Africa, despite the implementation of multiple control interventions, the prevalence of malaria infection and clinical cases remains high. The primary tool for vector control against malaria in this region is the use of long-lasting insecticide-treated nets (LLINs), which could potentially be enhanced by combining them with indoor residual spraying (IRS) to achieve a synergistic effect in protection. The objective of this study was to assess whether the national deployment of LLINs, with or without IRS, effectively protected against Plasmodium falciparum infection and uncomplicated clinical cases (UCC) in Benin. A case-control study was conducted, encom-19 passing all age groups, in the urban area of Djougou and the rural area of Cobly. The participants were selected from a cross-sectional survey, which included 2,080 individuals in the urban area and 2,770 individuals in the rural area. In the urban area, it was found that sleeping under LLINs did not confer significant protection against malaria infection and UCC when compared to no intervention. However, certain neighborhoods benefited from a notable reduction in infection rates ranging from 65% to 85%. In the rural area, the use of LLINs alone, IRS alone, or their combination did not provide additional protection compared to no intervention. Comparing LLINs alone to IRS alone, and LLINs combined with IRS, it was observed that the latter two options conferred 61% and 65% protection, respectively, against malaria infection. In terms of UCC, IRS alone and LLINs combined with IRS provided individual protection rates of 52% and 54%, respectively, when compared to LLINs alone. In both urban and rural areas, the use of LLINs alone, IRS alone, and their combination did not demonstrate significant individual protection against malaria infection and clinical cases when compared to no intervention. In the setting of this study, LLNS combined or not with IRS is not sufficient to eliminate malaria. In addition to the interventions themselves, it is important to recognize environmental conditions, housing design, neglected social groups like gender-marginalized and adolescents, and socio-economic conditions act as barriers to effective malaria prevention. Addressing these factors is crucial in order to facilitate malaria elimination efforts in sub-Saharan Africa.