Assessing the cost-effectiveness of phased withdrawal of dichlorodiphenyltrichloroethane from indoor residual spraying activities
1
Statistical Sciences, University of Cape Town, Cape Town, South Africa
Popul. Med. 2026;8(Supplement Supplement 1):A477
ABSTRACT
BACKGROUND:
Malaria continues to pose a significant public health threat in Limpopo Province, South Africa, despite considerable progress in reducing transmission over the past two decades. Central to these gains has been the large-scale implementation of indoor residual spraying (IRS) using dichlorodiphenyltrichloroethane (DDT), which has historically proven effective in suppressing Anopheles vector populations and disrupting local transmission cycles. However, concerns over the environmental effect of DDT, together with the operational sustainability of IRS have led to renewed interest in next-generation insecticides and integrated vector control strategies. Extreme weather events, such as heatwaves and flooding, have been shown to trigger mosquito population surges and localised malaria outbreaks, even in areas with high IRS coverage.
METHODS:
Recent modelling studies highlight the importance of incorporating climatic drivers, insecticide selection, and both the timing and coverage of spray operations into malaria transmission models. These conditions affect vector survival and malaria seasonality and may compromise both existing control measures and the cost-effectiveness of IRS activities. While next-generation insecticides have demonstrated promising residual activity in controlled trials, there remains a need to evaluate their real-world effectiveness in dynamic and heterogeneous transmission settings, particularly when combined with larviciding. Furthermore, understanding these factors enables programmes to evaluate phased DDT withdrawal in IRS modelling scenarios and inform the design of cost-effective integrated control strategies.
RESULTS:
We present a spatially explicit malaria transmission model for Limpopo province at multiple administrative levels, integrated with health economic modelling to evaluate the cost-effectiveness of interventions. Through scenario simulations, we assess the potential of next-generation insecticides and integrated control packages to sustain and accelerate progress toward malaria elimination.
CONCLUSIONS:
Our findings aim to guide strategic planning for IRS scale-down and resource allocation to support effective withdrawal of DDT from IRS activities.
Malaria continues to pose a significant public health threat in Limpopo Province, South Africa, despite considerable progress in reducing transmission over the past two decades. Central to these gains has been the large-scale implementation of indoor residual spraying (IRS) using dichlorodiphenyltrichloroethane (DDT), which has historically proven effective in suppressing Anopheles vector populations and disrupting local transmission cycles. However, concerns over the environmental effect of DDT, together with the operational sustainability of IRS have led to renewed interest in next-generation insecticides and integrated vector control strategies. Extreme weather events, such as heatwaves and flooding, have been shown to trigger mosquito population surges and localised malaria outbreaks, even in areas with high IRS coverage.
METHODS:
Recent modelling studies highlight the importance of incorporating climatic drivers, insecticide selection, and both the timing and coverage of spray operations into malaria transmission models. These conditions affect vector survival and malaria seasonality and may compromise both existing control measures and the cost-effectiveness of IRS activities. While next-generation insecticides have demonstrated promising residual activity in controlled trials, there remains a need to evaluate their real-world effectiveness in dynamic and heterogeneous transmission settings, particularly when combined with larviciding. Furthermore, understanding these factors enables programmes to evaluate phased DDT withdrawal in IRS modelling scenarios and inform the design of cost-effective integrated control strategies.
RESULTS:
We present a spatially explicit malaria transmission model for Limpopo province at multiple administrative levels, integrated with health economic modelling to evaluate the cost-effectiveness of interventions. Through scenario simulations, we assess the potential of next-generation insecticides and integrated control packages to sustain and accelerate progress toward malaria elimination.
CONCLUSIONS:
Our findings aim to guide strategic planning for IRS scale-down and resource allocation to support effective withdrawal of DDT from IRS activities.
| eISSN: | 2654-1459 |
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