Insecticide resistance and role in malaria transmission of Anopheles funestus populations from Zambia and Zimbabwe

Choi, Kwang Shik; Christian, Riann; Nardini, Luisa; Wood, Oliver R; Agubuzo, Eunice; Muleba, Mbanga; Munyati, Shungu; Makuwaza, Aramu; Koekemoer, Lizette L.; Brooke, Basil D.; Hunt, Richard H.; Coetzee, Maureen

doi:10.1186/preaccept-2101307024135398

Cited by 26 publications

(50 citation statements)

References 7 publications

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“…exposed to deltamethrin in Côte d’Ivoire and Uganda, respectively [ 13 , 15 ], and a recent study in Zambia (recording knockdown rather than mortality) found time to knockdown with deltamethrin was approximately 14-fold higher in a wild population of An. funestus than in the laboratory susceptible strain [ 16 ]. The highest resistance ratios reported to date are from Burkina Faso where, in 2012, An.…”

Section: Discussionmentioning

confidence: 99%

When a discriminating dose assay is not enough: measuring the intensity of insecticide resistance in malaria vectors

Bagi

Grisales

Corkill

et al. 2015

Malar J

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BackgroundGuidelines from the World Health Organization for monitoring insecticide resistance in disease vectors recommend exposing insects to a predetermined discriminating dose of insecticide and recording the percentage mortality in the population. This standardized methodology has been widely adopted for malaria vectors and has provided valuable data on the spread and prevalence of resistance. However, understanding the potential impact of this resistance on malaria control requires a more quantitative measure of the strength or intensity of this resistance.MethodsBioassays were adapted to quantify the level of resistance to permethrin in laboratory colonies and field populations of Anopheles gambiae sensu lato. WHO susceptibility tube assays were used to produce data on mortality versus exposure time and CDC bottle bioassays were used to generate dose response data sets. A modified version of the CDC bottle bioassay, known as the Resistance Intensity Rapid Diagnostic Test (I-RDT), was also used to measure the knockdown and mortality after exposure to different multipliers of the diagnostic dose. Finally cone bioassays were used to assess mortality after exposure to insecticide treated nets.ResultsThe time response assays were simple to perform but not suitable for highly resistant populations. After initial problems with stability of insecticide and bottle washing were resolved, the CDC bottle bioassay provided a reproducible, quantitative measure of resistance but there were challenges performing this under field conditions. The I-RDT was simple to perform and interpret although the end point selected (immediate knockdown versus 24 h mortality) could dramatically affect the interpretation of the data. The utility of the cone bioassays was dependent on net type and thus appropriate controls are needed to interpret the operational significance of these data sets.ConclusionsIncorporating quantitative measures of resistance strength, and utilizing bioassays with field doses of insecticides, will help interpret the possible impact of resistance on vector control activities. Each method tested had different benefits and challenges and agreement on a common methodology would be beneficial so that data are generated in a standardized format. This type of quantitative data are an important prerequisite to linking resistance strength to epidemiological outcomes.

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Section: Discussionmentioning

confidence: 99%

When a discriminating dose assay is not enough: measuring the intensity of insecticide resistance in malaria vectors

Bagi

Grisales

Corkill

et al. 2015

Malar J

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“…gambiae and An. funestus in Zambia to varying degrees, particularly in areas with high IRS coverage [10,11]. Zambia has recently switched to spraying with organophosphates, specifically pirimiphos-methyl (Actellic CS) to combat this resistance.…”

Section: Introductionmentioning

confidence: 99%

Knowledge, attitudes and practices assessment of malaria interventions in rural Zambia

et al. 2020

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Background: Despite rapid upscale of insecticide-treated nets (ITNs) and indoor residual spraying (IRS), malaria remains a major source of morbidity and mortality in Zambia. Uptake and utilization of these and novel interventions are often affected by knowledge, attitudes and practices (KAP) amongst persons living in malariaendemic areas. The aims of this study were to assess malaria KAP of primary caregivers and explore trends in relation to ITN use, IRS acceptance and mosquito density in two endemic communities in Luangwa and Nyimba districts, Zambia. Methods: A cohort of 75 primary caregivers were assessed using a cross-sectional, forced-choice malaria KAP survey on ITN use, IRS acceptance and initial perception of a novel spatial repellent (SR) product under investigation. Entomological sampling was performed in participant homes using CDC Miniature Light Traps to relate indoor mosquito density with participant responses. Results: Ninety-nine percent of participants cited bites of infected mosquitoes as the route of malaria transmission although other routes were also reported including drinking dirty water (64%) and eating contaminated food (63%). All caregivers agreed that malaria was a life-threatening disease with the majority of caregivers having received malaria information from health centers (86%) and community health workers (51%). Cumulatively, self-reported mosquito net use was 67%. Respondents reportedly liked the SR prototype product but improvements on color, shape and size were suggested. Overall, 398 mosquitoes were captured from light-trap collections, including 49 anophelines and 349 culicines. Insecticide treated nets use was higher in households from which at least one mosquito was captured. Conclusions: The current study identified misconceptions in malaria transmission among primary caregivers indicating remaining knowledge gaps in educational campaigns. Participant responses also indicated a misalignment between a low perception of IRS efficacy and high stated acceptance of IRS, which should be further examined to better understand uptake and sustainability of other vector control strategies. While ITNs were found to be used in study households, misperceptions between presence of mosquitoes and bite protection practices did exist. This study highlights the importance of knowledge attitudes and practice surveys, with integration of entomological sampling, to better guide malaria vector control product development, strategy acceptance and compliance within endemic communities.

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“…funestus due to its strong association with humans and human habitations [1,2]. However, the development of insecticide resistance across the region [5,6] has seen vector control programs compromised in some places [7][8][9]. This has also played an important role in the slow-down of the gains made in malaria control over the past 10 years in Africa [10,11].…”

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Genetic differentiation and population structure of Anopheles funestus from Uganda and the southern African countries of Malawi, Mozambique, Zambia and Zimbabwe

Kaddumukasa

Wright²,

Muleba

et al. 2020

Parasites Vectors

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Background: Anopheles funestus (s.s.) is a primary vector of the malaria parasite Plasmodium falciparum in Africa, a human pathogen that causes almost half a million deaths each year. The population structure of An. funestus was examined in samples from Uganda and the southern African countries of Malawi, Mozambique, Zambia and Zimbabwe.Methods: Twelve microsatellites were used to estimate the genetic diversity and differentiation of An. funestus from 13 representative locations across five countries. These were comprised of four sites from Uganda, three from Malawi and two each from Mozambique, Zambia and Zimbabwe.Results: All loci were highly polymorphic across the populations with high allelic richness and heterozygosity. A high genetic diversity was observed with 2-19 alleles per locus and an average number of seven alleles. Overall, expected heterozygosity (H e ) ranged from 0.65 to 0.79. When samples were pooled three of the 12 microsatellite loci showed Hardy-Weinberg equilibrium. Unsupervised Bayesian clustering analysis of microsatellite data revealed two clusters with An. funestus samples from Mozambique, Uganda and Zambia falling into one group and Malawi and Zimbabwe into another. The overall genetic differentiation between the populations was moderate (F ST = 0.116). Pairwise differentiation between the pairs was low but significant. A weak but significant correlation was established between genetic and geographical distance for most populations.Conclusions: High genetic diversity revealed by the loci with low to moderate differentiation, identified two clusters among the An. funestus populations. Further research on the population dynamics of An. funestus in east and southern Africa is essential to understand the implications of this structuring and what effect it may have on the efficient implementation of mosquito vector control strategies.

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Insecticide resistance and role in malaria transmission of Anopheles funestus populations from Zambia and Zimbabwe

Cited by 26 publications

References 7 publications

When a discriminating dose assay is not enough: measuring the intensity of insecticide resistance in malaria vectors

When a discriminating dose assay is not enough: measuring the intensity of insecticide resistance in malaria vectors

Knowledge, attitudes and practices assessment of malaria interventions in rural Zambia

Genetic differentiation and population structure of Anopheles funestus from Uganda and the southern African countries of Malawi, Mozambique, Zambia and Zimbabwe

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