Insecticide Treated Polyethylene Sheeting for Prevention of Malaria in Emergencies: an Observational Cohort Study in a Refugee Setting in Sierra Leone

During the last decade public and private sector organisations, under the leadership of the Roll Back Malaria (RBM) Initiative, have recognised the need to work together to bring complementary expertise to the task of identifying and developing vector control tools appropriate to humanitarian crises. Insecticide Treated Polyethylene Sheeting (ITPS), is one such tool emerging from this process and is being produced commercially. ITPS is based on the standard polyethylene sheeting that is issued routinely as temporary shelter for people affected by emergencies. During manufacture the pyrethroid insecticide, deltamethrin, is extruded with the polyethylene into three-ply laminated sheets, comprising an inner low-density laminate and two, outer high-density laminates. The insecticide release characteristics enable the deltamethrin to diffuse slowly to the outer surfaces and to become available for pick-up by any insect that lands on the surface. Consequently ITPS has dual purpose: to provide shelter but with vector-control potential. Deployment and erection of ITPS is done in the same way as standard tarpaulin shelters.

Until now evaluation of ITPS has been limited to small scale entomological testing in scientifically controlled environment 'entomological platforms' in Asian and 'experimental huts' in rural African settings (Refer to Citation Section). Before any novel control tool can go forward for recommendation by the WHO, or be used routinely in humanitarian crises, clear demonstration of impact on malaria morbidity in emergency refugee settings is essential. A Phase III field evaluation was therefore conducted to evaluate the impact of ITPS on malaria incidence in young children in an area of intense transmission. A unique feature of this trial was its setting - a true emergency - in two newly built refugee camps for Liberian refugees displaced to Sierra Leone. The findings offer insight into the effectiveness of ITPS when used in a scenario for which it was purposefully designed.