Escalation of Pyrethroid Resistance in the Malaria Vector Anopheles funestus Induces a Loss of Efficacy of Piperonyl Butoxide-Based Insecticide-Treated Nets in Mozambique

Jacob M. Riveron, Silvie Huijben, Williams Tchapga, Magellan Tchouakui, Murielle J. Wondji, Micareme Tchoupo, Helen Irving, Nelson Cuamba, Mara Maquina, Krijn Paaijmans, Charles S. Wondji

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Insecticide resistance poses a serious threat to insecticide-based interventions in Africa. There is a fear that resistance escalation could jeopardize malaria control efforts. Monitoring of cases of aggravation of resistance intensity and its impact on the efficacy of control tools is crucial to predict consequences of resistance. Methods: The resistance levels of an Anopheles funestus population from Palmeira, southern Mozambique, were characterized and their impact on the efficacy of various insecticide-treated nets established. Results: A dramatic loss of efficacy of all long-lasting insecticidal nets (LLINs), including piperonyl butoxide (PBO)-based nets (Olyset Plus), was observed. This An. funestus population consistently (2016, 2017, and 2018) exhibited a high degree of pyrethroid resistance. Molecular analyses revealed that this resistance escalation was associated with a massive overexpression of the duplicated cytochrome P450 genes CYP6P9a and CYP6P9b, and also the fixation of the resistance CYP6P9a-R allele in this population in 2016 (100%) in contrast to 2002 (5%). However, the low recovery of susceptibility after PBO synergist assay suggests that other resistance mechanisms could be involved. Conclusions: The loss of efficacy of pyrethroid-based LLINs with and without PBO is a concern for the effectiveness of insecticide-based interventions, and action should be taken to prevent the spread of such super-resistance.

Original languageEnglish (US)
Article numberjiz139
Pages (from-to)467-475
Number of pages9
JournalJournal of Infectious Diseases
Volume220
Issue number3
DOIs
StatePublished - Jul 2 2019

Keywords

  • An. funestus
  • Mozambique
  • cytochrome P450
  • insecticide resistance
  • long-lasting insecticidal nets
  • malaria
  • metabolic resistance
  • vector control

ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases

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