The impact of pyrethroid resistance on the efficacy and effectiveness of bednets for malaria control in Africa

  1. Thomas S Churcher  Is a corresponding author
  2. Natalie Lissenden
  3. Jamie T Griffin
  4. Eve Worrall
  5. Hilary Ranson
  1. Imperial College London, United Kingdom
  2. Liverpool School of Tropical Medicine, United Kingdom

Abstract

Long lasting pyrethroid treated bednets are the most important tool for preventing malaria. Pyrethroid resistant Anopheline mosquitoes are now ubiquitous in Africa though the public health impact remains unclear, impeding the deployment of more expensive nets. Meta-analyses of bioassay studies and experimental hut trials are used to characterise how pyrethroid resistance changes the efficacy of standard bednets, and those containing the synergist piperonyl butoxide (PBO), and assess its impact on malaria control. New bednets provide substantial personal protection until high levels of resistance though protection may wane faster against more resistant mosquito populations as nets age. Transmission dynamics models indicate that even low levels of resistance would increase the incidence of malaria due to reduced mosquito mortality and lower overall community protection over the life-time of the net. Switching to PBO bednets could avert up to 0.5 clinical cases per person per year in some resistance scenarios.

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The following data sets were generated

Article and author information

Author details

  1. Thomas S Churcher

    MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
    For correspondence
    thomas.churcher@imperial.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8442-0525
  2. Natalie Lissenden

    Liverpool School of Tropical Medicine, Liverpool, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  3. Jamie T Griffin

    MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  4. Eve Worrall

    Liverpool School of Tropical Medicine, Liverpool, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  5. Hilary Ranson

    Liverpool School of Tropical Medicine, Liverpool, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.

Funding

Medical Research Council

  • Thomas S Churcher

Department for International Development

  • Thomas S Churcher

European Research Council

  • Hilary Ranson

Innovative Vector Control Consortium

  • Thomas S Churcher

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Simon I Hay, Institute for Health Metrics and Evaluation, United States

Version history

  1. Received: March 16, 2016
  2. Accepted: August 18, 2016
  3. Accepted Manuscript published: August 22, 2016 (version 1)
  4. Version of Record published: September 15, 2016 (version 2)

Copyright

© 2016, Churcher et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Thomas S Churcher
  2. Natalie Lissenden
  3. Jamie T Griffin
  4. Eve Worrall
  5. Hilary Ranson
(2016)
The impact of pyrethroid resistance on the efficacy and effectiveness of bednets for malaria control in Africa
eLife 5:e16090.
https://doi.org/10.7554/eLife.16090

Share this article

https://doi.org/10.7554/eLife.16090

Further reading

  1. Modelling the effectiveness of bednets against mosquitoes and malaria.

    1. Epidemiology and Global Health
    Sean V Connelly, Nicholas F Brazeau ... Jeffrey A Bailey
    Research Article

    Background:

    The Zanzibar archipelago of Tanzania has become a low-transmission area for Plasmodium falciparum. Despite being considered an area of pre-elimination for years, achieving elimination has been difficult, likely due to a combination of imported infections from mainland Tanzania and continued local transmission.

    Methods:

    To shed light on these sources of transmission, we applied highly multiplexed genotyping utilizing molecular inversion probes to characterize the genetic relatedness of 282 P. falciparum isolates collected across Zanzibar and in Bagamoyo district on the coastal mainland from 2016 to 2018.

    Results:

    Overall, parasite populations on the coastal mainland and Zanzibar archipelago remain highly related. However, parasite isolates from Zanzibar exhibit population microstructure due to the rapid decay of parasite relatedness over very short distances. This, along with highly related pairs within shehias, suggests ongoing low-level local transmission. We also identified highly related parasites across shehias that reflect human mobility on the main island of Unguja and identified a cluster of highly related parasites, suggestive of an outbreak, in the Micheweni district on Pemba island. Parasites in asymptomatic infections demonstrated higher complexity of infection than those in symptomatic infections, but have similar core genomes.

    Conclusions:

    Our data support importation as a main source of genetic diversity and contribution to the parasite population in Zanzibar, but they also show local outbreak clusters where targeted interventions are essential to block local transmission. These results highlight the need for preventive measures against imported malaria and enhanced control measures in areas that remain receptive to malaria reemergence due to susceptible hosts and competent vectors.

    Funding:

    This research was funded by the National Institutes of Health, grants R01AI121558, R01AI137395, R01AI155730, F30AI143172, and K24AI134990. Funding was also contributed from the Swedish Research Council, Erling-Persson Family Foundation, and the Yang Fund. RV acknowledges funding from the MRC Centre for Global Infectious Disease Analysis (reference MR/R015600/1), jointly funded by the UK Medical Research Council (MRC) and the UK Foreign, Commonwealth & Development Office (FCDO), under the MRC/FCDO Concordat agreement and is also part of the EDCTP2 program supported by the European Union. RV also acknowledges funding by Community Jameel.