The long-lasting insecticide-treated mosquito net (LLIN) has established itself in a few years as a privileged tool in the fight against malaria. To date, several brands have received either a provisional authorization from World Health Organization Pesticide Evaluation Scheme. However, the chemical efficacy and survival of these brands differ depending on the conditions of use from one country to another. What are the factors that impact this efficiency and sustainability?.
Methods: LLIN follow-ups (every 6 months) were carried out in three malaria-endemic district of Benin: Toffo and Tori-Bossito and Ouesse for 2 years. This cohort study involved 900 LINs, 300 per brand (DawaPlus®2.0, DuraNet® and PermaNet®2.0) and aims to assess the bio-effectiveness and survival of LLINs. The colorimetric test allowed us to quantify the insecticide lost over time.
Results: Overall, 283 out of 900 LLINs (enrolled at the start of the study) were found and assessed after 24 months of use. The reasons for the losses were: LLINs destroyed (27.3%), LLINs moved (13.9%) and LLINs used for other purposes (10.1%). A significant decrease in the survivorship of DawaPlus®2.0, PermaNet®2.0 and DuraNet® LLINs was observed after 2 years, 51%, 53.3% and 34% respectively. The efficacy of the three LLINs also didn't meet WHO requirements (80% mortality for WHO cone tests).
Conclusions: The decrease in the survival of LLINs due to the increasing accidental destruction during this study highlights the need to develop and implement new strategies such as behavior change awareness to manage this vital means of fighting malaria.