Modelling

Many organisations are working toward the goal of malaria eradication across a spectrum of interventions, including vector control, drugs and vaccines. This impact modelling conducted by IVCC and Imperial College London (part of the Malaria Modelling Consortium) considered the impact of an integrated and layered vector control toolbox deployed across sub-Saharan Africa, alongside drugs and vaccines. Allowing for several assumptions on the availability of existing products, the results demonstrate that each of the targeted vector control interventions, when appropriately layered, could potentially have a transformational impact on malaria transmission and eradication.

As part of the ZERO by 40 initiative, IVCC set out to analyse the potential economic and societal impact of malaria on rural communities across sub-Saharan Africa. The result is modelling research, undertaken by Derek W. Willis PhD and Nick Hamon PhD, which explores how the prevalence of malaria can have a major influence on not just health but also wider aspects of rural life, such as poverty rates, labour productivity, education and gender equality. With an enhanced understanding of the impact that malaria eradication can have on people living in these regions, the need for collaborative efforts to develop and deploy effective vector control tools can be clearly demonstrated.

The objective of IRM strategies is to preserve or prolong the susceptibility of mosquito vectors to insecticides, in order to maintain the effectiveness of insecticide-based vector control interventions. Persistent insecticides sprayed onto house walls, and incorporated into insecticide-treated nets, provide long-acting, cost-effective control of vector-borne diseases such as malaria and leishmaniasis. The high concentrations that occur immediately post-deployment may kill both resistant and susceptible insects. However, insecticide concentration, and therefore killing ability, declines in the months after deployment. As concentrations decline, resistant insects start to survive while susceptible insects are still killed. This leads to a ‘window of selection’ a period where susceptible mortality is higher than resistant and evolution of resistance may occur. Modelling, based on field data collected over 18 months by the Liverpool School of Tropical Medicine (LSTM), has highlighted the importance of these windows of selection and the need to minimise sub-lethal exposure and quantify how different insecticide use strategies promote the evolution of resistance.