Insecticide‐treated plastic tarpaulins for control of malaria vectors in refugee camps

Abstract

Abstract. Spraying of canvas tents with residual pyrethroid insecticide is an established method of malaria vector control in tented refugee camps. In recent years, plastic sheeting (polythene tarpaulins) has replaced canvas as the utilitarian shelter material for displaced populations in complex emergencies. Advances in technology enable polythene sheeting to be impregnated with pyrethroid during manufacture. The efficacy of such material against mosquitoes when erected as shelters under typical refugee camp conditions is unknown. Tests were undertaken with free-flying mosquitoes on entomological study platforms in an Afghan refugee camp to compare the insecticidal efficacy of plastic tarpaulin sprayed with deltamethrin on its inner surface (target dose 30 mg/m 2 ), tarpaulin impregnated with deltamethrin (initially ! 30 mg/m 2 ) during manufacture, and a tent made from the factory impregnated tarpaulin material. Preliminary tests done in the laboratory with Anopheles stephensi Liston (Diptera: Culicidae) showed that 1-min exposure to factory-impregnated tarpaulins would give 100% mortality even after outdoor weathering in a temperate climate for 12 weeks. Outdoor platform tests with the erected materials (baited with human subjects) produced mosquito mortality rates between 86±100% for sprayed or factory-impregnated tarpaulins and tents (average $40 anophelines and $200 culicines/per platform/ night), whereas control mortality (with untreated tarpaulin) was no more than 5%. Fewer than 20% of mosquitoes blood-fed on human subjects under either insecticide-treated or non-treated shelters. The tarpaulin shelter was a poor barrier to host-seeking mosquitoes and treatment with insecticide did not reduce the proportion blood-feeding. Even so, the deployment of insecticide-impregnated tarpaulins in refugee camps, if used by the majority of refugees, has the potential to control malaria by killing high proportions of mosquitoes and so reducing the average life expectancy of vectors (greatly reducing vectorial capacity), rather than by directly protecting refugees from mosquito bites. Mass coverage with deltamethrin-sprayed or impregnated tarpaulins or tents has strong potential for preventing malaria in displaced populations affected by conflict.

Cross-Border Malaria: A Major Obstacle for Malaria Elimination

“…The benefits of sleeping under LLINs need to be highlighted through education, and LLINs being made available through social marketing, as has been done for refugees from Afghanistan in Pakistan (Rowland and Nosten, 2001). Alternative approaches such as the provision of insecticide-treated hammocks for people frequenting forest areas in border areas (Magris et al, 2007;Thang et al, 2009), deltamethrin-sprayed tarpaulins or tents, and premethrin-treated blankets and top sheets provide more promising options for people overnighting in the forest (Graham et al, 2002;Rowland and Nosten, 2001). These protective measures achieve the goal of reducing exposure to infected vectors for populations who do not live in traditional housing each night, a feature common to people in border areas.…”

Child health in complex emergencies

“…24 Deltamethrin-treated plastic tarpaulins in Afghan refugee camps effectively killed mosquitoes for prolonged periods. 25 …”

Evaluation of Barrier Treatments on Native Vegetation in A Southern California Desert Habitat

“…Examples of treated perimeter vegetation include jungle, forest, or hedges surrounding a house, village, or park (Anderson et al 1991, Perich et al 1993 or even open grasslands (Kettle 1949). Examples of treated artificial perimeter substrates include interior and exterior walls (Huehne 1971, Lee et al 1997, suspended or spread sheets (Elnaiem et al 1999, Graham et al 2002, bed nets (Hill et al 2006), and livestock fencing (Bauer et al 2006a(Bauer et al , 2006b. A range of insecticides has been used, from DDT in early studies (Lindquist and McDuffie 1945, Trapido 1947, Ludvik 1950, Nair 1951 to various pyrethroids and other toxicants in more recent work (Sathantriphop 2006, Xue 2008.…”