Physical integrity of three Long-Lasting Insecticidal Net products 30 months after a mass-distribution campaign in Benin

Abstract Background The effectiveness of long-lasting insecticidal nets (LLINs) mainly relies on their physical integrity, an important indicator of the LLINs durability in households. The present study aims to assess this physical integrity for three widely used LLIN products: DawaPlus®2.0, PermaNet®2.0 (polyester) and DuraNet® (polyethylene), distributed in Benin during the mass campaign of 2014. Methods The study was conducted from October 2014 to June 2017 in three districts of Benin: Tori-Bossito, Toffo, and Ouesse. Nine hundred LLINs (a cohort of 300 LLINs per product) in use and found hanging on sleeping materials were selected and tagged. Every six months, the LLIN attrition and their physical condition was monitored. The holes were counted by category allowed to calculate the proportionate hole index (pHI) and classify the LLINs into "good ", "serviceable" or "torn" categories. Factors associated with loss of integrity have also been identified following World Health Organization Guidelines. Results After 30 months of use, 55.9% (n= 503; 95% CI: 52.6-59.2) of the LLINs were lost. Attritions due to physical damage were similar between the LLIN products and were respectively 28.3% for PermaNet® 2.0, 29.7% for DawaPlus® 2.0, and 31% for DuraNet® (p˃0.05). The mean pHI was significantly higher for DuraNet® LLINs (pHI= 1431) than DawaPlus® 2.0 (pHI =366) and PermaNet® 2.0 (pHI =321) (<0.001). A significant difference was also observed between the proportion of LLINs in “torn” condition and included 8.7% of PermaNet® 2.0, 14.3% of DawaPlus® 2.0, and 34.1% of DuraNet® (p <0.001). The use of LLINs every night, the frequency of washing and other factors were significantly associated with the physical damage of the LLINs (p <0.001). Conclusion These results suggest that the physical barrier conferred by the LLIN can be significantly affected during the normal course of its use depending on the type of product distributed. National malaria programs must, therefore, consider the physical integrity performance in local conditions in the choice of LLIN product to be distributed. Keywords: LLINs, physical integrity, pHI, malaria, Benin.