Evidence map›Paper›PMID 40514700›Full record

ArticleMalaria journal2025

Phenotypic and genotypic insecticide resistance profiles of main malaria vectors in Kwale county, coastal Kenya.

Miguel Okoko, Jonathan Karisa, Rehema Gona, Tobias Odongo, Bruno Otieno, Festus Yaa, Brian Bartilol, Peter Meli, Zedekiah Ondieki, Mercy Tuwei and 5 more

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Article in Malaria journal, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.

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0cells of the map it votes in
4citing papers in PubMed
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1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

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3 · Its place in the literature

Who cites it

4 citing papers in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

15 authors.

Miguel OkokoKEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research - Coast, Kilifi, Kenya. okokogerson@gmail.com.
Jonathan KarisaKEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research - Coast, Kilifi, Kenya.
Rehema GonaKEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research - Coast, Kilifi, Kenya.
Tobias OdongoKEMRI Centre for vector-borne disease Control, Kwale, Kenya.
Bruno OtienoKEMRI Centre for vector-borne disease Control, Kwale, Kenya.
Festus YaaKEMRI Centre for vector-borne disease Control, Kwale, Kenya.
Brian BartilolKEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research - Coast, Kilifi, Kenya.
Peter MeliKEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research - Coast, Kilifi, Kenya.
Zedekiah OndiekiKEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research - Coast, Kilifi, Kenya.
Mercy TuweiKEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research - Coast, Kilifi, Kenya.
Caroline WanjikuKEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research - Coast, Kilifi, Kenya.
Faiz SheePwani University, Kilifi, Kenya.
Carlos ChaccourISGlobal, Barcelona, Spain.
Caroline KiuruISGlobal, Barcelona, Spain.
Marta F MaiaKEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research - Coast, Kilifi, Kenya. MMaia@kemri-wellcome.org.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundLong-lasting insecticidal nets are the primary malaria vector control measure in coastal Kenya. In 2018, phenotypic resistance to pyrethroids and low frequency of L1014S kdr mutation were reported in the Anopheles gambiae complex. Since then, additional pyrethroid-treated nets were distributed in 2021. The objectives of this study were to determine the insecticide resistance profiles of An. gambiae and Anopheles funestus from Kwale County and evaluate potential resistance mechanisms.

methodsFrom July 2023 to May 2024, adult and larval collections of An. funestus and An. gambiae mosquitoes were done with the aim of conducting insecticide susceptibility bioassays using WHO protocol for permethrin, deltamethrin, bendiocarb, DDT and pirimiphos-methyl. Species found resistant to pyrethroids were subjected to synergism testing by pre-exposure to piperonyl-butoxide (PBO). This was followed by genotyping of resistance-associated mutations in An. funestus (CYP6P9a, CYP6P9b, GSTe2-L119F and 6.5kb S.V) and An. gambiae (kdr L1014S and L1014F). Sibling species identification was done using PCR. The association between genetic markers and phenotypic resistance was explored using logistic regression.

resultsA total of 1826 An. gambiae and 715 An. funestus were used in insecticide susceptibility bioassays. Both An. gambiae and An. funestus were resistant to permethrin (mortality, 58.7% and 57.1, respectively) and deltamethrin (mortality 51% and 76%, respectively), but susceptible to DDT, bendiocarb and Pirimiphos-methyl. Pre-exposure to PBO increased susceptibility to deltamethrin in both species. Both kdr west and east were detected in Anopheles arabiensis (L1014S freq = 0.083, L1014F freq = 0.063) and Anopheles quadriannulatus (L1014S freq = 0.074, L1014F freq = 0.043) at low frequencies. Anopheles funestus sensu stricto and Anopheles rivolurum had the presence of CYP6Pa, CYP6Pb, 6.5kb S.V and GSTe2-L119F, with low allele frequencies. There were no significant associations between the genotypes and phenotypic profile.

conclusionsMalaria vectors in Kwale are resistant to pyrethroids. PBO fully restored susceptibility, indicating this resistance could be caused by metabolic mechanism. The presence of kdr and metabolic resistance alleles suggests a recent selection on Anopheles mosquitoes. Pyrethroid-only nets may not fully ensure community protection against malaria in coastal Kenya due to resistance. Operational failure remains uncertain, requiring further studies. Net distribution programs should consider pyrethroid-PBO nets to enhance malaria control effectiveness.

Indexed as

AnophelesInsecticide ResistanceInsecticidesMosquito VectorsAnimalsGenotypeKenyaLarvaMalariaPhenotypePyrethrinsInsecticidesPyrethrinsAn. funestusAn. gambiaeCoastal KenyaInsecticide resistanceKwaleMetabolic resistance

Identifiers

PMID40514700
PMCPMC12164100

What OpenQuestion holds

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LicenceCC BY-NC-ND
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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.