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

ECHO, UNHCR Country Office Freetown, World Health Organization, Wageningen University, London School of Hygiene and Tropical Medicine, National Malaria Control Programme Sierra Leone, Institut de Recherche pour le Developpement

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.

Children 4months-36months enrolled who resided in Largo refugee camp under Untreated plastic sheeting (interior wall and ceiling lining)

Children 4months-36months enrolled who resided in Largo refugee camp under Insecticide treated plastic sheeting (interior wall and ceiling lining)

Children 4months-36months enrolled who resided in Tobanda refugee camp under Untreated plastic sheeting (ceiling and interior roof lining)

Children 4months-36months enrolled who resided in Tobanda refugee camp under Insecticide treated plastic sheeting (ceiling and interior roof lining)

Insecticide Treated Polyethylene Sheeting 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.

Standard polyethylene sheeting that is issued routinely as temporary shelter for people affected by emergencies. Standard untreated plastic sheeting is Identical to ITPS but without the incorporation of insecticide.

The primary outcome was the malaria incidence rate between children in each study arm (ITPS V's UPS) in each refugee camp. Between Dec 2003 and July 2004, daily monitoring of children in both camps was conducted from health screening points. Any child presenting with fever or reported fever in the last 24 hours was administered a clinical questionnaire based on the Integrated Management of Childhood Illness (IMCI), after which a RDT was taken to confirm malaria positivity. Malaria incidence rate was estimated as the total number of malaria episodes per person year over the course of the trial.

In each study cohort (ITPS V's UPS arms in two camps) haemoglobin levels were monitored at 3 monthly intervals (three times during the 8 month monitoring period) using a HemoCue® photometer that was calibrated daily when used.

Symptoms or conditions considered to be potential adverse events related to ITPS usage (dizziness, inflamed/watery eyes, mucosal irritation, muscle cramps/tremors, nausea, runny nose, skin burning, skin itching, skin paraesthesia, skin rash, skin redness, sneezing and tachycardia (pulse rate >150)) were recorded during the monitoring period in both ITPS and UPS intervention arms in each camp. A symptom listed repeatedly within a seven day period for each child was considered to be the same adverse event as was any child having more than one of the symptoms present on a single day.

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?"

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