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

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)

[img]
Preview
Text
98561.pdf - Published Version
Available under License Creative Commons Attribution.

499kB

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 > Institute of Biodiversity Animal Health and Comparative 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

University Staff: Request a correction | Enlighten Editors: Update this record

Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
601601Ecological determinants of African malaria vector behaviour and their implications for controlHeather FergusonEuropean Commission (EC)AvecnetRI BIODIVERSITY ANIMAL HEALTH & COMPMED