Simple and Inexpensive Preparation of Long-lasting Insecticidal Nets Via Co-adsorption of Pyrethroid and Oligomer

Abstract

Insecticide-treated bed nets, or Long-Lasting Insecticidal Nets (LLINs), are valuable tools in the effort to control mosquitoes (Anopheles gambiae ), the carriers of the malaria parasite, in Africa. Insecticide (pyrethroid) is retained by LLINs when subjected to washing, which allows for their long-term effectiveness. A simple and inexpensive method for preparing LLINs based upon the co-adsorption of the pyrethroid deltamethrin and oligomer or monomer when commercial nets are dipped in aqueous solution is described here. An aqueous solution of monomer, 2-hydroxy ethyl methacrylate, or its oligomers, was first prepared. The net was soaked in the aqueous solution for a few minutes, then subjected to the removal of its excess water. The majority of experiments involved in situ oligomerization by exposing the treated net to sunlight and warm ambient temperatures. LLINs synthesized in the laboratory as such retained 70— 90 % of their ability to kill mosquitoes after six successive washes and 70 % of their original deltamethrin content, both benchmarks of which were comparable to the performance of 1^st generation commercial LLIN products. A cost analysis indicated that chemicals required for the derivatization solution would cost only an additional 1.15 USD beyond that of the pyrethroid. The approach developed here to prepare LLINs from local or selected sources of bed nets and insecticide agents allows for their preparation in remote settings, would reduce costs, and simplify the transportation and distribution compared to employing commercial LLINs prepared abroad, and may also be valuable for modifying military, agricultural, and outdoor sports textiles.