Insecticide Treated Polyethylene Sheeting for Prevention of Malaria in Emergencies

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

A Phase III malaria prevention trial was conducted in two camps of Liberian refugees in Sierra Leone using Insecticide Treated Polyethylene Sheeting (ITPS) or untreated polyethylene sheeting (UPS) randomly deployed to defined sectors of each camp. The ITPS was impregnated with pyrethroid insecticide during manufacture. In Largo camp the ITPS or UPS was attached to inner walls and ceilings of shelters, while in Tobanda the ITPS or UPS was used to line the ceiling and roof only. Cohorts of children up to 3 years of age were cleared of malaria parasites and monitored for up to 8 months post construction for possible malaria re-infection. Installation teams and refugee groups were blinded as to whether the sheeting was insecticide treated or not.

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.

Inclusion Criteria:

• Resident of LARGO or TOBANDA Refugee Camp, Sierra Leone, West Africa
• Child whose guardian has given informed consent for their child to be enrolled into monitoring
• Child aged 4 months to 3 years

Exclusion Criteria:

• Residents who answer "Yes" to the question, "Do you anticipate/plan on moving out of this shelter or camp in the next 6-12 months?"
• Children who have a serious illness other than malaria, based on guardian report.
• Children who have experienced adverse reactions to Amodiaquine or Artesunate on a previous occasion.
• Guardians of children who answer "Yes" to the question, "Do you anticipate/plan on moving out of this shelter or camp in the next 12 months?"