Repellents as Added Control Measure to Long Lasting Insecticidal Nets to Target the Residual Transmission in Southeast Asia: a Step Forwards to Malaria Elimination

The scaling up of Long Lasting Insecticidal Nets (LLIN) and the expansion of Indoor Residual Spraying (IRS) has contributed to a significant decrease of malaria worldwide. However these control methods tackle only indoor and night biting vectors. The proportion of transmission occurring outdoors and before sleeping hours or so-called "residual transmission" is steadily increasing and may compromise the effort towards malaria elimination.

The purpose of this study is to raise evidence on the effectiveness of mass use of topical repellents in addition to LLINs in controlling malaria infections.

A multidisciplinary approach will be used to collect information on the most important factors that contribute to the successful reduction of "residual malaria transmission". In a first objective the epidemiological efficacy of repellents on prevalence of malaria carriers and malaria incidence will be assessed. To achieve this goal 98 communities will be randomly assigned to one of two treatment arms (LLIN and LLIN + repellent). Within a community a cross sectional random sample of 65 people will be drawn at the beginning and the end of the malaria season to obtain an estimate of the malaria prevalence. The second objective will handle the entomological efficacy and persistence of the topical repellent on malaria vectors. And lastly the acceptability, adherence and adequacy of the topical repellents will be studied in a third objective.