Ngufor, C., Chouaïbou, M., Tchicaya, E., Loukou, B., Kesse, N., N’Guessan, R., Johnson, P. , Koudou, B. and Rowland, M. (2014) Combining organophosphate-treated wall linings and long-lasting insecticidal nets fails to provide additional control over long-lasting insecticidal nets alone against multiple insecticide-resistant Anopheles gambiae in Côte d’Ivoire: an experimental hut trial. Malaria Journal, 13, 396. (doi: 10.1186/1475-2875-13-396) (PMID:25301219) (PMCID:PMC4203900)
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Publisher's URL: http://dx.doi.org/10.1186/1475-2875-13-396
Abstract
<b>Background</b> Insecticide-treated wall lining (ITWL) is a new concept in malaria vector control. Some <i>Anopheles gambiae</i> populations in West Africa have developed resistance to all the main classes of insecticides. It needs to be demonstrated whether vector control can be improved or resistance managed when non-pyrethroid ITWL is used alone or together with long-lasting insecticidal nets (LLINs) against multiple insecticide-resistant vector populations.<p></p> <b>Methods</b> Two experimental hut trials were carried out as proofs of concept to evaluate pirimiphos methyl (p-methyl)-treated plastic wall lining (WL) and net wall hangings (NWH) used alone and in combination with LLINs against multiple insecticide-resistant <i>An. Gambiae</i> in Tiassalé, Côte d’Ivoire. Comparison was made to commercial deltamethrin WL and genotypes for <i>kdr</i> and <i>ace-1R</i> resistance were monitored.<p></p> <b>Results</b> The <i>kdr</i> and <i>ace-1R</i> allele frequencies were 0.83 and 0.44, respectively. <i>Anopheles gambiae</i> surviving discriminating concentrations of deltamethrin and p-methyl in WHO resistance tests were 57 and 96%, respectively. Mortality of free-flying <i>An. Gambiae</i> in huts with p-methyl WL and NWH (66 and 50%, respectively) was higher than with pyrethroid WL (32%; P < 0.001). Mortality with LLIN was 63%. Mortality with the combination of LLIN plus p-methyl NWH (61%) or LLIN plus p-methyl WL (73%) did not significantly improve upon the LLIN alone or p-methyl WL or NWH alone. Mosquitoes bearing the <i>ace-1R</i> were more likely to survive exposure to p-methyl WL and NWH. Selection of heterozygote and homozygote <i>ace-1R</i> or <i>kdr</i> genotypes was not less likely after exposure to combined LLIN and p-methyl treatments than to single p-methyl treatment. Blood-feeding rates were lower in huts with the pyrethroid LLIN (19%) than with p-methyl WL (72%) or NWH (76%); only LLIN contributed to personal protection.<p></p> <b>Conclusions</b> Combining p-methyl WL or NWH with LLINs provided no improvement in <i>An. Gambiae</i> control or personal protection over LLIN alone in southern Côte d’Ivoire; neither did the combination manage resistance. Additional resistance mechanisms to <i>kdr</i> and <i>ace-1R</i> probably contributed to the survival of pyrethroid and organophophate-resistant mosquitoes. The study demonstrates the challenge that malaria control programmes will face if resistance to multiple insecticides continues to spread.<p></p>
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Johnson, Dr Paul |
| Authors: | Ngufor, C., Chouaïbou, M., Tchicaya, E., Loukou, B., Kesse, N., N’Guessan, R., Johnson, P., Koudou, B., and Rowland, M. |
| College/School: | College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine |
| Journal Name: | Malaria Journal |
| Publisher: | BioMed Central |
| ISSN: | 1475-2875 |
| Copyright Holders: | Copyright © 2014 The Authors |
| First Published: | First published in Malaria Journal 13(1):396 |
| Publisher Policy: | Reproduced under a Creative Commons License |
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