Increased prevalence of insecticide resistance in Anopheles coluzzii populations in the city of Yaoundé, Cameroon and influence on pyrethroid-only treated bed net efficacy

Bamou, Roland, Kopya, Edmond, Nkahe, Leslie Diane, Menze, Benjamin, Awono-Ambene, Parfait, Tchuinkam, Timoléon, Njiokou, Flobert, Wondji, Charles ORCID: https://orcid.org/0000-0003-0791-3673 and Nkondjio, Christophe (2021) 'Increased prevalence of insecticide resistance in Anopheles coluzzii populations in the city of Yaoundé, Cameroon and influence on pyrethroid-only treated bed net efficacy'. Parasite, Vol 28, Issue 8.

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Abstract

In Cameroon, pyrethroid-only long-lasting insecticidal nets (LLINs) are still largely used for malaria
control. The present study assessed the efficacy of such LLINs against a multiple-resistant population of the major
malaria vector, Anopheles coluzzii, in the city of Yaoundé via a cone bioassay and release-recapture experimental
hut trial. Susceptibility of field mosquitoes in Yaoundé to pyrethroids, DDT, carbamates and organophosphate
insecticides was investigated using World Health Organization (WHO) bioassay tube tests. Mechanisms of insecticide
resistance were characterised molecularly. Efficacy of unwashed PermaNet 2.0 was evaluated against untreated
control nets using a resistant colonised strain of An. coluzzii. Mortality, exophily and blood feeding inhibition were
estimated. Field collected An. coluzzii displayed high resistance with mortality rates of 3.5% for propoxur (0.1%),
4.16% for DDT (4%), 26.9% for permethrin (0.75%), 50.8% for deltamethrin (0.05%), and 80% for bendiocarb
(0.1%). High frequency of the 1014F west-Africa kdr allele was recorded in addition to the overexpression of several
detoxification genes, such as Cyp6P3, Cyp6M2, Cyp9K1, Cyp6P4 Cyp6Z1 and GSTe2. A low mortality rate (23.2%)
and high blood feeding inhibition rate (65%) were observed when resistant An. coluzzii were exposed to unwashed
PermaNet 2.0 net compared to control untreated net (p < 0.001). Furthermore, low personal protection (52.4%)
was observed with the resistant strain, indicating reduction of efficacy. The study highlights the loss of efficacy of
pyrethroid-only nets against mosquitoes exhibiting high insecticide resistance and suggests a switch to new generation
bed nets to improve control of malaria vector populations in Yaoundé.

Item Type:	Article
Subjects:	QX Parasitology > Insects. Other Parasites > QX 510 Mosquitoes QX Parasitology > Insects. Other Parasites > QX 515 Anopheles QX Parasitology > Insects. Other Parasites > QX 600 Insect control. Tick control WA Public Health > Health Problems of Special Population Groups > WA 395 Health in developing countries WC Communicable Diseases > Tropical and Parasitic Diseases > WC 750 Malaria WC Communicable Diseases > Tropical and Parasitic Diseases > WC 765 Prevention and control
Faculty: Department:	Biological Sciences > Vector Biology Department
Digital Object Identifer (DOI):	https://doi.org/10.1051/parasite/2021003
Depositing User:	Samantha Sheldrake
Date Deposited:	31 Mar 2021 09:09
Last Modified:	31 Mar 2021 09:09
URI:	https://archive.lstmed.ac.uk/id/eprint/17404

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