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Multicentre studies of insecticide-treated durable wall lining in Africa and South-East Asia: entomological efficacy and household acceptability during one year of field use

Louisa A Messenger1*, Abrahan Matias2, Antonio Nkulu Manana2, Joseph B Stiles-Ocran3, Steve Knowles3, Daniel A Boakye4, Mamadou B Coulibaly5, Marie-Louise Larsen6, Amadou S Traoré5, Bréhima Diallo5, Mamadou Konaté5, Amadou Guindo5, Sékou F Traoré5, Chris EG Mulder7, Hoan Le8, Immo Kleinschmidt1 and Mark Rowland1

Author Affiliations

1 Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK

2 Medical Care Development International (MCDI), Malabo, Equatorial Guinea

3 Entomology Research Unit, Malaria Control Centre, AngloGold Ashanti Ltd., Obuasi, Ghana

4 Noguchi Memorial Institute for Medical Research, UG, Accra, Ghana

5 Vector Genomics and Proteomics, Malaria Research and Training Center (MRTC), University of Sciences, Techniques and Technologies, Bamako, Mali

6 Technical Institute of Denmark (DTU), Lyngby, Denmark

7 Agricultural Research Station (Pty) Ltd., Friedenhiem JT 282, Nelspruit, South Africa

8 Vestergaard Frandsen Laboratories, 253/9 Minh Khai, Hai Ba Trung district, Hanoi, Vietnam

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Malaria Journal 2012, 11:358  doi:10.1186/1475-2875-11-358

Published: 29 October 2012

Abstract

Background

Indoor residual spraying (IRS) is a primary method of malaria vector control, but its potential impact is constrained by several inherent limitations: spraying must be repeated when insecticide residues decay, householders can tire of the annual imposition and campaign costs are recurrent. Durable lining (DL) can be considered an advanced form of long-lasting IRS where insecticide is gradually released from an aesthetically attractive wall lining material to provide vector control for several years. A multicentre trial was carried out in Equatorial Guinea, Ghana, Mali, South Africa and Vietnam to assess the feasibility, durability, bioefficacy and household acceptability of DL, compared to conventional IRS or insecticide-treated curtains (LLITCs), in a variety of operational settings.

Methods

This study was conducted in 220 households in traditional rural villages over 12-15 months. In all sites, rolls of DL were cut to fit house dimensions and fixed to interior wall surfaces (usually with nails and caps) by trained teams. Acceptability was assessed using a standardized questionnaire covering such topics as installation, exposure reactions, entomology, indoor environment, aesthetics and durability. Bioefficacy of interventions was evaluated using WHO cone bioassay tests at regular intervals throughout the year.

Results

The deltamethrin DL demonstrated little to no decline in bioefficacy over 12-15 months, supported by minimal loss of insecticide content. By contrast, IRS displayed a significant decrease in bioactivity by 6 months and full loss after 12 months. The majority of participants in DL households perceived reductions in mosquito density (93%) and biting (82%), but no changes in indoor temperature (83%). Among those households that wanted to retain the DL, 73% cited protective reasons, 20% expressed a desire to keep theirs for decoration and 7% valued both qualities equally. In Equatorial Guinea, when offered a choice of vector control product at the end of the trial (DL, IRS or LLITCs), DL consistently emerged as the most popular intervention regardless of the earlier household allocation.

Conclusions

Just as long-lasting insecticidal nets overcame several of the technical and logistical constraints associated with conventionally treated nets and then went to scale, this study demonstrates the potential of DL to sustain user compliance and overcome the operational challenges associated with IRS.

Keywords:
Durable wall lining; ZeroVector®; IRS; Malaria control; Acceptability; Efficacy; Durability