Using a spatially explicit mathematical model to evaluate the impact of an integrated vector management system on mosquitoes: a study of their population dynamics and malaria transmission potential

Malaria continues to be a serious health risk in Africa and parts of Asia despite sustained control efforts. A thorough understanding of the response of vector populations and malaria transmission to control interventions is required to eliminate the disease. An existing ecological model for mosquito population dynamics is extended into a met population model with movement of adult mosquitoes between patches in search of human hosts. This model is used to investigate the effects of the interventions on mosquito populations. In addition, an existing feeding cycle model is extended to study the impact of integrated vector management on both feeding success and survival probability of mosquitoes. Finally, the results derived from the two models are used to compute malaria transmission intensities, assuming the human population is always constant. Projections from the met population model show spatial variations in both vector populations and malaria transmissions. In all scenarios investigated, the use of interventions is projected to have a significant impact on vector populations with reductions of at least 48%. Attractive toxic sugar baits (ATSB) are projected to have the greatest impact, resulting in a reduction of 76% in vector populations from the baseline equilibrium values. A combination of all three interventions at 80% coverage each leads to a reduction of 82% in vector populations. For the investigations on the entomological inoculation rate, all intervention scenarios are projected to reduce equilibrium baseline entomological inoculation rate (EIR) by at least 87%. Again, attractive toxic sugar baits are the most effective single intervention, reducing baseline EIR by about 98%. A combination of all interventions at 80% each is projected to reduce EIR by up to 99.8%.An IVM that consists of LLINs, IRS, and ATSBs has the potential to significantly reduce both vector populations as well as malaria transmissions.