Treated Bed nets (ITN). In this paper we focus on vector control and thus on malaria prevention interventions. In addition to IRS and ITN for vector control, we also include Environmental Management (EM) because it has yielded promising results in certain environments and becomes increasingly more important as vectors develop resistance to insecticides and parasites to drugs [5], [6], [7]. As no intervention in isolation is able to control malaria transmission and as mosquitoes adapt to some interventions, integration and coordination of various prevention interventions is essential to achieve malaria elimination. Integrated Vector Management (IVM) should provide intelligent management of prevention interventions, the optimal use of existing resources to fight malaria, advocacy and social mobilization as well as capacity building [8]. Assessing the costs and effectiveness of different combinations of IVM interventions requires a comprehensive understanding of the many indirect, delayed, and nonlinear feedback effects that IVM interventions can have. Building such understanding can be supported considerably by experimentation with computer simulation models that allow the design and analysis of different scenarios and policies in a risk free environment [9]. This paper develops a simulation based Malaria Management Model (MMM). The MMM contains a representation of malaria transmission processes, vector control, and case management, and it dynamically links these components to population development, health, education, and economic production. A first pilot version calibrates and applies the model to the aggregated sub Saharan African region and assesses the costs and benefits of the continued use of DDT for IRS. One fundamental and often controversial category of vector control interventions is Indoor Residual Spraying (IRS). IRS is a predominantly chemical vector control designed to eliminate or repel mosquitoes. This method with its protective features against malaria transmission merits special attention because vectors can develop resistances to the sprayed chemicals and because the sprayed chemicals can be a threat for both human health and the environment [10], [11]. One of the twelve World Health Organization-(WHO) approved insecticides for IRS is dichloro-diphenyl-trichloroethane (DDT). According to WHO [12], DDT is the most cost-effective and longest-lasting insecticide but at the same time also the most environmentally persistent [13]. When sprayed indoors, it can pose risks to human health [14]. Therefore, the use of DDT for vector control remains controversial. The Stockholm Convention on Persistent Organic Pollutants aims at a complete phase out of DDT but currently allows it for disease vector control when locally safe, effective, and affordable alternatives are not available. With the Malaria Management Model, we calculate the costs of eliminating malaria either with the currently used mix of IVM interventions with DDT as the most prominent insecticide or with alternative insecticides. With malaria elimination we refer to the interruption of transmission, which requires continuous measures to prevent re-establishment of transmission. Malaria eradication, on the other hand, would imply the permanent reduction to zero of the worldwide incidence of infection where intervention measures are no longer needed (e.g., [4]). For putting the question about the continued use of DDT for IRS versus its rapid phase out into perspective, we calculate the same costs and benefits for alternative combinations of IVM interventions, i.e., we calculate the costs of eliminating malaria in sub Saharan Africa and how these costs compare to the gains in GDP that would result from malaria elimination for each combination. We perform these calculations for an ambitious short-term time horizon (elimination by 2025) and a mid-term DDT versus Non-DDT Malaria Control time horizon (elimination by 2035). With this pilot application of the MMM we thus address the following research questions: 1. What is the amount of resources necessary to gradually scale up the current combination of vector control interventions for achieving malaria elimination in 2025 or in 2035, respectively? 2. How does this amount compare to the gain in GDP that could be achieved through malaria elimination? 3. What are the costs and benefits of the continued use of DDT for IRS versus its rapid phase out? The indirect or external costs of DDT, i.e., the costs related to the environmental and health impacts, are difficult to assess in monetary terms, and they also depend on value judgments and risk attitudes [15]. For this reason we only calculate the direct costs such as the price per DDT-intervention and the direct benefits such as impacts on gross domestic production (GDP). We add some indications of external costs and risks to highlight how they can affect evaluations of the effectiveness of the continued use of DDT for IRS versus its rapid phase out. 4. What is the amount of resources necessary to gradually scale up alternative combinations of vector control interventions for achieving malaria elimination in 2025 or 2035, respectively? 5. How do these amounts compare to the gain in GDP that could be achieved through malaria elimination? An effective IVM strategy needs to be designed based on location-specific ecological and epidemiological characteristics and social factors [5], [15]. It is thus very difficult to determine the optimal combination of interventions for scaling up vector control to achieve malaria elimination in the SSA region. Sub Saharan Africa is a broad and diverse region with varied eco-epidemiolog- ical situations. In this study we do not aim at identifying a specific combination of interventions that would fit all situations. Instead, we recognize that different interventions fit different situations. Based on this consideration, we analyze the likely necessary budget to eliminate malaria for the aggregate SSA region under different assumptions regarding what type of interventions might be most needed without assuming that all interventions will be identical in all locations. We then compare these costs to the likely economic benefits of malaria elimination (cost-effectiveness of different combinations of vector control interventions). Finally, for our pilot application of the MMM to the question about the continued use of DDT for IRS, the aggregate SSA region provides a sufficiently homogenous level of analysis. Further applications of the MMM, however, will require more location-specific analysis, e.g., country-level analyses. The prototype Malaria Management Model illustrates how a computer based scenario analysis tool can inform debates on malaria control policies in general and on the continued use of DDT for IRS versus its rapid phase out in specific. The model separates issues of scientific uncertainty such as the impact of DDT for IRS on human health and the environment from disagreement over values, i.e., over the weight that should be put on longer term human health, economic and environmental impacts versus short term reductions in direct costs when DDT is used for IRS. Simulation models cannot resolve such disagreements. However, they can highlight the role of the different aspects related to the design of IVM interventions and provide a user-friendly tool that allows decision makers to explore the impact of different component weights on the costs and benefits of such interventions. Simulation models create more systematic mechanisms for analyzing alternative interventions and making informed trade offs. PLoS ONE | www.plosone.org 2 November 2011 | Volume 6 | Issue 11 | e27771