Pre-intervention characteristics of the mosquito species in Benin in preparation for a randomized controlled trial assessing the efficacy of dual active-ingredient long-lasting insecticidal nets for controlling insecticide-resistant malaria vectors

Autor: Bruno Akinro, Natacha Protopopoff, Martin Akogbeto, Gil Germain Padonou, Boulais Yovogan, Razaki Ossè, Louisa A. Messenger, Constantin Adoha, Arthur Sovi, Corine Ngufor, Edouard Dangbenon, Saïd Chitou, Mark Rowland, Aurore Ogouyemi Hounto, Jackie Cook, Immo Kleinschmidt, Manfred Accrombessi, Hilaire Akpovi
Rok vydání: 2021
Předmět:
Insecticides
Veterinary medicine
Mosquito Control
Anopheles Gambiae
Anopheles gambiae
Disease Vectors
Mosquitoes
Insecticide Resistance
Geographical Locations
chemistry.chemical_compound
Medical Conditions
Medicine and Health Sciences
Anopheles nili
Benin
Malaria
Falciparum
Multidisciplinary
Pyrethroid
Eukaryota
Agriculture
Insects
Infectious Diseases
Medicine
Agrochemicals
Research Article
medicine.drug
Arthropoda
Death Rates
Science
Plasmodium falciparum
Bendiocarb
Mosquito Vectors
Biology
Population Metrics
parasitic diseases
Anopheles
Parasitic Diseases
medicine
Animals
Humans
Insecticide-Treated Bednets
Population Biology
Organisms
Biology and Life Sciences
Tropical Diseases
biology.organism_classification
medicine.disease
Invertebrates
Malaria
Insect Vectors
Species Interactions
chemistry
Vector (epidemiology)
People and Places
Africa
Zoology
Entomology
Permethrin
Zdroj: PLoS ONE
PLoS ONE, Vol 16, Iss 5, p e0251742 (2021)
ISSN: 1932-6203
Popis: Background This study provides detailed characteristics of vector populations in preparation for a three-arm cluster randomized controlled trial (RCT) aiming to compare the community impact of dual active-ingredient (AI) long-lasting insecticidal nets (LLINs) that combine two novel insecticide classes–chlorfenapyr or pyriproxifen–with alpha-cypermethrin to improve the prevention of malaria transmitted by insecticide-resistant vectors compared to standard pyrethroid LLINs. Methods The study was carried out in 60 villages across Cove, Zangnanando and Ouinhi districts, southern Benin. Mosquito collections were performed using human landing catches (HLCs). After morphological identification, a sub-sample of Anopheles gambiae s.l. were dissected for parity, analyzed by PCR for species and presence of L1014F kdr mutation and by ELISA-CSP to identify Plasmodium falciparum sporozoite infection. WHO susceptibility tube tests were performed by exposing adult An. gambiae s.l., collected as larvae from each district, to 0.05% alphacypermethrin, 0.75% permethrin, 0.1% bendiocarb and 0.25% pirimiphos-methyl. Synergist assays were also conducted with exposure first to 4% PBO followed by alpha-cypermethrin. Results An. gambiae s.l. (n = 10807) was the main malaria vector complex found followed by Anopheles funestus s.l. (n = 397) and Anopheles nili (n = 82). An. gambiae s.l. was comprised of An. coluzzii (53.9%) and An. gambiae s.s. (46.1%), both displaying a frequency of the L1014F kdr mutation >80%. Although more than 80% of people slept under standard LLIN, human biting rate (HBR) in An. gambiae s.l. was higher indoors [26.5 bite/person/night (95% CI: 25.2–27.9)] than outdoors [18.5 b/p/n (95% CI: 17.4–19.6)], as were the trends for sporozoite rate (SR) [2.9% (95% CI: 1.7–4.8) vs 1.8% (95% CI: 0.6–3.8)] and entomological inoculation rate (EIR) [21.6 infected bites/person/month (95% CI: 20.4–22.8) vs 5.4 (95% CI: 4.8–6.0)]. Parous rate was 81.6% (95%CI: 75.4–88.4). An. gambiae s.l. was resistant to alpha-cypermethrin and permethrin but, fully susceptible to bendiocarb and pirimiphos-methyl. PBO pre-exposure followed by alpha-cypermethrin treatment induced a higher 24 hours mortality compared to alphacypermethrin alone but not exceeding 40%. Conclusions Despite a high usage of standard pyrethroid LLINs, the study area is characterized by intense malaria transmission. The main vectors An. coluzzii and An. gambiae s.s. were both highly resistant to pyrethroids and displayed multiple resistance mechanisms, L1014F kdr mutation and mixed function oxidases. These conditions of the study area make it an appropriate site to conduct the trial that aims to assess the effect of novel dual-AI LLINs on malaria transmitted by insecticide-resistant vectors.
Databáze: OpenAIRE
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