Maps and metrics of insecticide-treated net access, use, and nets-per-capita in Africa from 2000-2020

Bertozzi‐Villa, Amelia; Bever, Caitlin A.; Koenker, Hannah; Weiss, Daniel J.; Vargas-Ruiz, Camilo; Nandi, A.; Gibson, Harry S.; Harris, Jonathan; Battle, Katherine E.; Rumisha, Susan F.; Keddie, Suzanne; Amratia, Punam; Arambepola, Rohan; Cameron, Ewan; Chestnutt, Elisabeth G.; Collins, Emma; Millar, Justin; Mishra, Swapnil; Rozier, Jennifer; Symons, Tasmin L.; Twohig, Katherine A.; Hollingsworth, T. Déirdre; Gething, Peter W.; Bhatt, Samir

doi:10.1038/s41467-021-23707-7

Cited by 93 publications

(100 citation statements)

References 48 publications

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“…Consequently, damaged LLINs would be expected to retain some community effect against mosquito populations that are susceptible to their chemistry. Despite this, the median retention time of LLINs is well below three years in many settings (1.64 years across sub-Saharan Africa and 1.66 years for Uganda) (34) . Given evidence that perception of physical integrity is the primary consideration in retention (35) , developing more durable LLIN products may have epidemiological impacts beyond what would be indicated by studies of mosquito behaviour, due to improved retention.…”

Section: Discussionmentioning

confidence: 99%

LLIN Evaluation in Uganda Project (LLINEUP) – The durability of long-lasting insecticidal nets treated with and without piperonyl butoxide (PBO) in Uganda

Mechan

Katureebe

Tuhaise

et al. 2022

Preprint

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Long Lasting Insecticidal Nets (LLINs) provide physical and chemical protection from the bites of malaria transmitting mosquitoes but growing resistance to pyrethroid insecticides threatens their effectiveness. To restore insecticidal effect, pyrethroid LLINs supplemented with the synergist piperonyl butoxide (PBO) have been developed. However, the durability of these new products in the field must be assessed. In 2017-2018 the Ugandan Ministry of Health undertook a mass-distribution of LLINs with and without PBO, providing an opportunity to assess durability. A pragmatic cluster-randomised trial was embedded into the 2017-2018 national distribution. A total of 104 clusters were included with each receiving one of four LLIN products, two of which contained pyrethroid and PBO (Olyset Plus and PermaNet 3.0) and two which had pyrethroid only (Olyset Net and PermaNet 2.0). Nets were sampled at baseline, 12 months, and 25 months post-distribution to assess physical condition, chemical content, and bioefficacy. Physical condition was quantified using proportionate Hole Index and total chemical content measured using high-performance liquid chromatography (HPLC). Bioefficacy was assessed by performing three-minute WHO Cone and Wireball assays with pyrethroid-resistant An. gambiae s.s., with 1hr knockdown 24hr mortality recorded. There was no difference in the physical durability of LLINs with PBO and their pyrethroid-only equivalents (p=0.644), with 12.5% of nets in the too torn pHI category after 25 months. However, nets from thatched-roof housing were more likely to be too torn compared to iron-roofed housing (29.7% vs 11.2% respectively, p<0.001). The pyrethroid content of all nets remained relatively stable across timepoints but PBO content declined by 55% (P<0.001) and 58% (p<0.001) for Olyset Plus and PermaNet 3.0 respectively. Both Olyset Plus and PermaNet 3.0 were highly effective against pyrethroid-resistant mosquitoes when new, knocking down 98.93% and 100% respectively. However the bioefficacy of both PBO LLINs declined over time, with Olyset Plus knocking down 45.72% (95% CI: 22.84-68.62, p=0.021) and Permanet 3.0 knocking down 78.57% (95% CI: 63.57-93.58, p<0.001) after 25 months. Both pyrethroid-only LLINs performed poorly in bioassays. Here we demonstrate that both Olyset Plus and PermaNet 3.0 are as durable as their pyrethroid-only equivalents and had superior bioefficacy against pyrethroid-resistant An. gambiae. However, the superiority of PBO-LLINs decreased with operational use, correlating with a reduction in total PBO content. This decline in bioefficacy after just two years is concerning and there is an urgent need to assess the durability of PBO LLINs in other settings. Additionally, the disparity in physical damage between nets collected from traditional and improved housing highlights a need to consider socioeconomic factors when assessing operational lifespan.

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Section: Discussionmentioning

confidence: 99%

LLIN Evaluation in Uganda Project (LLINEUP) – The durability of long-lasting insecticidal nets treated with and without piperonyl butoxide (PBO) in Uganda

Mechan

Katureebe

Tuhaise

et al. 2022

Preprint

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“…As an initial illustration of the method's practical relevance, we here present an incomplete list of recent applications. In the time-period of May-Sep 2021, we find applications of the SPDE-approach to Gaussian fields in astronomy (Levis et al, 2021), health (Mannseth et al, 2021;Scott, 2021;Moses et al, 2021;Bertozzi-Villa et al, 2021;Moraga et al, 2021;Asri and Benamirouche, 2021), engineering (Zhang et al, 2021), theory (Ghattas and Willcox, 2021;Sanz-Alonso and Yang, 2021a;Lang and Pereira, 2021;Bolin and Wallin, 2021), environmetrics Beloconi et al, 2021;Vandeskog et al, 2021a;Wang and Zuo, 2021;Wright et al, 2021;Gómez-Catasús et al, 2021;Valente and Laurini, 2021b;Bleuel et al, 2021;Florêncio et al, 2021;Valente and Laurini, 2021a;Hough et al, 2021), econometrics (Morales and Laurini, 2021;Maynou et al, 2021), agronomy (Borges da Silva et al, 2021), ecology (Martino et al, 2021;Sicacha-Parada et al, 2021;Williamson et al;Bell et al, 2021;Humphreys et al;Xi et al, 2021;Fecchio et al), urban planning (Li, 2021), imaging (Aquino et al, 2021), modelling of forest fires (Taylor et al; Lindenmayer et al), fisheries (Babyn et al, 2021;van Woesik and Cacciapaglia, 2021;Jarvis et al, 2021;…”

Section: Some Recent Applicationsmentioning

confidence: 99%

“…One of the first large scale applications of the GMRF/SPDE models was Bhatt et al (2015); Bertozzi-Villa et al (2021), that modelled the effect of malaria control over time. The results showed that infection prevalence in Africa had halved between 2000 and 2015, with an estimated 542-763 million (95% credible interval) of averted cases attributable to preventative interventions such as insecticide-treated nets.…”

Section: Malaria Modelling With Spatio-temporal Spdesmentioning

confidence: 99%

The SPDE approach for Gaussian and non-Gaussian fields: 10 years and still running

Lindgren¹,

Bolin²,

Rue³

2021

Preprint

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Gaussian processes and random fields have a long history, covering multiple approaches to representing spatial and spatio-temporal dependence structures, such as covariance functions, spectral representations, reproducing kernel Hilbert spaces, and graph based models. This article describes how the stochastic partial differential equation approach to generalising Matérn covariance models via Hilbert space projections connects with several of these approaches, with each connection being useful in different situations. In addition to an overview of the main ideas, some important extensions, theory, applications, and other recent developments are discussed. The methods include both Markovian and non-Markovian models, non-Gaussian random fields, non-stationary fields and space-time fields on arbitrary manifolds, and practical computational considerations.

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“…However, whilst at least half of the African population is now sleeping under LLINs [5], pyrethroid resistance has become a common phenomenon in the most efficient vectors of Plasmodium parasites, especially those belonging to the Anopheles gambiae complex and the An. funestus group [6].…”

Section: Introductionmentioning

confidence: 99%

Patterns of Kdr-L995F Allele Emergence Alongside Detoxifying Enzymes Associated with Deltamethrin Resistance in Anopheles gambiae s.l. from North Cameroon

et al. 2022

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Understanding how multiple insecticide resistance mechanisms occur in malaria vectors is essential for efficient vector control. This study aimed at assessing the evolution of metabolic mechanisms and Kdr L995F/S resistance alleles in Anopheles gambiae s.l. from North Cameroon, following long-lasting insecticidal nets (LLINs) distribution in 2011. Female An. gambiae s.l. emerging from larvae collected in Ouro-Housso/Kanadi, Be-Centre, and Bala in 2011 and 2015, were tested for susceptibility to deltamethrin + piperonyl butoxide (PBO) or SSS-tributyl-phosphoro-thrithioate (DEF) synergists, using the World Health Organization’s standard protocol. The Kdr L995F/S alleles were genotyped using Hot Ligation Oligonucleotide Assay. Tested mosquitoes identified using PCR-RFLP were composed of An. arabiensis (68.5%), An. coluzzii (25.5%) and An. gambiae (6%) species. From 2011 to 2015, metabolic resistance increased in Ouro-Housso/Kanadi (up to 89.5% mortality to deltametnrin+synergists in 2015 versus <65% in 2011; p < 0.02), while it decreased in Be-Centre and Bala (>95% mortality in 2011 versus 42–94% in 2015; p < 0.001). Conversely, the Kdr L995F allelic frequencies slightly decreased in Ouro-Housso/Kanadi (from 50% to 46%, p > 0.9), while significantly increasing in Be-Centre and Bala (from 0–13% to 18–36%, p < 0.02). These data revealed two evolutionary trends of deltamethrin resistance mechanisms; non-pyrethroid vector control tools should supplement LLINs in North Cameroon.

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Maps and metrics of insecticide-treated net access, use, and nets-per-capita in Africa from 2000-2020

Cited by 93 publications

References 48 publications

LLIN Evaluation in Uganda Project (LLINEUP) – The durability of long-lasting insecticidal nets treated with and without piperonyl butoxide (PBO) in Uganda

LLIN Evaluation in Uganda Project (LLINEUP) – The durability of long-lasting insecticidal nets treated with and without piperonyl butoxide (PBO) in Uganda

The SPDE approach for Gaussian and non-Gaussian fields: 10 years and still running

Patterns of Kdr-L995F Allele Emergence Alongside Detoxifying Enzymes Associated with Deltamethrin Resistance in Anopheles gambiae s.l. from North Cameroon

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