'We spray and walk away': wall modifications decrease the impact of indoor residual spray campaigns through reductions in post-spray coverage

Malar J. 2020 Jan 17;19(1):30. doi: 10.1186/s12936-020-3102-6.

Abstract

Malaria prevalence has significantly reduced since 2000, largely due to the scale-up of vector control interventions, mainly indoor residual spraying (IRS) and long-lasting insecticide-treated nets (LLINs). Given their success, these tools remain the frontline interventions in the fight against malaria. Their effectiveness relies on three key ingredients: the intervention, the mosquito vector and the end-user. Regarding the intervention, factors such as the insecticide active ingredient(s) used and the durability and/or bio-efficacy of the tool over time are critical. For the vectors, these factors include biting and resting behaviours and the susceptibility to insecticides. Finally, the end-users need to accept and properly use the intervention. Whilst human attitude and behaviour towards LLINs are well-documented both during and after distribution, only initial coverage is monitored for IRS and in a few geographic settings the residual efficacy of the used product. Here, the historical evidence on end-users modifying their wall surfaces post-spraying is presented, a behaviour that has the potential to reduce actual IRS coverage, effectiveness and impact, as fewer people are truly protected. Therefore, clear guidelines on how to monitor IRS acceptability and/or coverage, both before, during and after spraying, are urgently needed as part of the Monitoring and Evaluation of malaria programmes.

Keywords: Communities; Compliance; Elimination; Insecticide; Residual efficacy; Vector control; Wall modification.

MeSH terms

  • Animals
  • DDT / administration & dosage
  • Housing / standards
  • Housing / trends*
  • Humans
  • India
  • Insecticide Resistance
  • Insecticide-Treated Bednets / standards
  • Insecticides / administration & dosage
  • Malaria / prevention & control*
  • Mosquito Control / methods*
  • Mosquito Control / standards
  • Mosquito Vectors*
  • Nitriles / administration & dosage
  • Pyrethrins / administration & dosage
  • South Africa

Substances

  • Insecticides
  • Nitriles
  • Pyrethrins
  • decamethrin
  • DDT