Congratulations on reaching the end of this course’s second chapter!

In the first chapter, we explored the mosquitoes that vector malaria and other vector-borne diseases between people. We discovered that controlling the mosquitoes was one of the most effective ways to prevent malaria, and that insecticide-based interventions were key to this. We also discovered that mosquitoes can develop and have developed resistance to the insecticides that had so effectively been used to control them.

Looking back at Chapter 2

In Chapter 2, we looked in more detail at how insecticide resistance can develop, and the impact it can have on the continued fight against malaria and other vector-borne diseases. In many villages like Nsuhyia, using insecticide-based interventions to prevent malaria and other vector-borne diseases has been commonplace for many years. However, there is evidence that the insecticide-based interventions are not as effective as they used to be.

Over many generations, mosquitoes less susceptible to the insecticides have been selected and now predominate in the population. The mosquitoes are becoming resistant, and malaria control is becoming more challenging. Something needs to be done. A more holistic, or integrated, approach to mosquito control needs to be implemented, and Insecticide Resistance Management is an important part of this.

We’ve discovered that insecticide resistance can also be selected for when the mosquitoes are exposed to the use of insecticides in agriculture, or to environmental pollution. The insecticides used in agriculture, by smallholders or gardeners, are often the same, or similar, to those used in vector control, which amplifies the problem.

We’ve seen that insecticide resistance can be based on physiological and behavioural changes that can reduce the effectiveness of insecticides from a given mode of action class. When such resistance impacts insecticides from different mode of action classes, it is called cross-resistance. Mosquitoes may also carry multiple resistance mechanisms, enabling them to survive exposure to multiple insecticides from different insecticidal mode of action classes.

Knowing which mosquito species are present, and their resistance status, is important information when designing an effective vector control programme. It is also needed for effective Insecticide Resistance Management. We have seen the importance of undertaking high-quality and standardised susceptibility monitoring studies. Sharing the results from such studies enables a larger-scale picture of the situation to be generated. Understanding the mechanisms of insecticide resistance will help us to identify the most effective approaches to control the mosquitoes, and to minimise further selection of these resistance mechanisms.

Looking forward to Chapter 3

A knowledge of the susceptibility status of a mosquito population is useful, but that alone won’t help us maintain effective vector control for the long term. We need to take proactive steps to minimise insecticide resistance development and to mitigate resistance already present. There may not always be an easy solution, and difficult decisions may need to be made.

In Chapter 3, we will investigate the practical steps that can be taken to implement Insecticide Resistance Management. We will also look at how these can be included in an integrated approach to vector control.

Why not put your understanding of the first two chapters to the test by continuing to play the mobile gaming app ‘Resistance 101’? After all, malaria vector control and Insecticide Resistance Management is all about what happens on the ground. And what better way to practice than applying your knowledge in this simulation game?

Author: Kevin Keyaert