Impact of long-lasting, insecticidal nets on anaemia and prevalence of Plasmodium falciparum among children under five years in areas with highly resistant malaria vectors

Abstract

BackgroundThe widespread use of insecticide-treated nets (LLINs) leads to the development of vector resistance to insecticide. This resistance can reduce the effectiveness of LLIN-based interventions and perhaps reverse progress in reducing malaria morbidity. To prevent such difficulty, it is important to know the real impact of resistance in the effectiveness of mosquito nets. Therefore, an assessment of LLIN efficacy was conducted in malaria prevention among children in high and low resistance areas.MethodsThe study was conducted in four rural districts and included 32 villages categorized as low or high resistance areas in Plateau Department, south-western Benin. Larvae collection was conducted to measure vector susceptibility to deltamethrin and knockdown resistance (kdr) frequency. In each resistance area, around 500 children were selected to measure the prevalence of malaria infection as well as the prevalence of anaemia associated with the use of LLINs.ResultsObserved mortalities of Anopheles gambiae s.s population exposed to deltamethrin ranged from 19 to 96%. Knockdown resistance frequency was between 38 and 84%. The prevalence of malaria infection in children under five years was 22.4% (19.9-25.1). This prevalence was 17.3% (14.2-20.9) in areas of high resistance and 27.1% (23.5-31.1) in areas of low resistance (p = 0.04). Eight on ten children that were aged six - 30 months against seven on ten of those aged 31–59 months were anaemic. The anaemia observed in the six to 30-month old children was significantly higher than in the 31–59 month old children (p = 0.00) but no difference associated with resistance areas was observed (p = 0.35). The net use rate was 71%. The risk of having malaria was significantly reduced (p < 0.05) with LLIN use in both low and high resistance areas. The preventive effect of LLINs in high resistance areas was 60% (95% CI: 40–70), and was significantly higher than that observed in low resistance areas (p < 0.05).ConclusionThe results of this study showed that the resistance of malaria vectors seems to date not have affected the impact of LLINs and the use of LLINs was highly associated with reduced malaria prevalence irrespective of resistance.

Performance of IRS on malaria prevalence and incidence using pirimiphos-methyl in the context of pyrethroids resistance in Koulikoro region, Mali

“…Since the two areas are comparable in terms of malaria epidemiology and interventions, this difference can be attributed to the added value of the IRS in the IRS area. Indeed, it is of common knowledge that each of the LLINs [9,18,19] and IRS [20][21][22] signi cantly reduce malaria burden when deployed separately. Thus, their integration is expected and supported by many studies [21,[23][24][25][26] to make more reduction in malaria burden compared to their respective single impact.…”

Insecticide resistance patterns in Uganda and the effect of indoor residual spraying with bendiocarb on kdr L1014S frequencies in Anopheles gambiae s.s.

“…A study in Malawi indicated a protective effect of LLINs in an area where Anopheles funestus showed low to moderate resistance against pyrethroids [10], and similar results were observed in Benin where pyrethroid-resistant Anopheles gambiae were the main vector [11]. A meta-analysis suggested that insecticide-treated nets (ITNs) continue to have an effect on entomological outcomes regardless of resistance [12].…”

Effect of pre-consultation testing on clinicians’ adherence to malaria test results and waiting time among children under 5 years in the Northern Zone of Volta Region of Ghana

“…The case fatality rate for malaria among children under 5 years of age in the region has also consistently decreased over the period 2016 to 2018, from 0.39 to 0.17 and to 0.13%, respectively. The region has 326 health facilities, of which 242 are public sector owned, 18 mission owned, 1 quasi-government (military hospital), and 65 privately owned [16,17]. The study involved two government-owned district hospitals in the northern zone of the region: Hohoe Government Hospital and Jasikan Government Hospital.…”