Indoor residual spraying (IRS) of insecticides on interior surfaces of residential structures is currently one of the most cost-effective means of reducing transmission of mosquito-borne human diseases such as malaria. However, IRS remains a controversial malaria control strategy because of the potential environmental and human health impacts of the insecticides utilized. Traditionally, Dichloro-Diphenyl-Trichloroethane (DDT) has been the preferred insecticide in IRS. The acute and chronic impacts of DDT exposure in humans remain uncertain. The negative environmental impacts from the widespread transport of DDT through ecosystems, while still uncertain, have been more clearly demonstrated, yet the costs of these impacts, when considered against clearly established costs of malaria-induced mortality and morbidity remain difficult to assess. Due to these uncertainties, policymakers must understand the conditions under which IRS is effective at reducing malaria transmission. In particular, a coverage rate of 85% of households is widely thought to be necessary to achieve significant, sustainable transmission reductions using IRS. If there are household-level costs associated with allowing IRS, then one would expect a household?s decision whether to accept IRS in their home to be a reflection of these costs as compared to the perceived benefits of malaria reduction, which are largely determined by the IRS decisions of other households. Thus this type of vector control strategy presents potential for an ?epidemiological externality.? This research will implement discrete choice experiments (DCEs) using 600 household surveys in 4 to 6 internally displaced person (IDP) camps in the Ugandan district of Gulu?where the malaria burden is particularly high and IRS has been heavily emphasized in vector control?to elicit preferences regarding the acceptance of alternative IRS programs and thereby (a) improve acceptance rates and (b) evaluate the potential for an epidemiological externality. Intellectual Merit While other economic and epidemiological research has produced theoretical models of epidemiological externalities, there is little applied work which quantifies the welfare impact of such a market failure in a specific epidemic or endemic context. The use of DCEs to estimate an econometric model that can be used for counterfactual analysis of such an externality is an important methodological innovation, which is of interest to development, environmental, and health economists. Broader Impacts Currently, the U.S. President?s Malaria Initiative has emphasized the importance of IRS as a major strategy for malaria control, and the World Health Organization (WHO) recommends DDT as the most cost-effective insecticide in IRS. Because of their costs and uncertain impacts on human health and the environment, it is important that IRS operations achieve the highest disease reduction possible and reflect the informed preferences of the targeted households. Moreover, understanding the confounding potential of epidemiological externalities can point to cooperative strategies to improve IRS efficacy. Thus, this research will aid policymaking by enabling a more precise targeting of well-designed IRS programs in areas where the most benefit is likely to be achieved.
