This project focuses on understanding the interactions between individual behavior and disease environment. There are two primary areas of focus: HIV/AIDS in Africa and Huntington''s disease in the United States. The first part of the project uses economic tools and theories to analyze the HIV epidemic in Africa, with a focus on developing optimal policies given individual decision making and constraints. The project begins by considering the determinants of the response of sexual behavior in Africa to the HIV epidemic, noting that in general there has been only a small decrease in the average number of sexual partners in Africa over the course of the HIV epidemic. This is in contrast to very large decreases in number of partners among high risk individuals elsewhere, such as the United States. The project explores whether some of the limited behavioral response to HIV might be due to a limited incentive to respond to HIV. More specifically, since other mortality risks in Africa are very high (for example, risks of death from malaria or maternal mortality) the cost of infection with HIV may not be as high as it would be for someone without these other mortality risks. The project tests this theory using information on variation in life expectancy across individuals within Africa. The results may have important policy implications. For example, if low life expectancy is a limiting factor in behavioral response, then increasing life expectancy by treating other illnesses may have an indirect positive impact on the HIV epidemic. The project also considers the link between HIV infections and economic activity in Africa. At an individual level, people who are involved in economic activity (for example, truck drivers) are more likely to be infected with HIV. This project looks to understand the link at the aggregate level, which may be more salient for policy. In order to complete the aggregate analysis, it is necessary to generate estimates of HIV incidence (new infections) and prevalence (total infections) over time. The project completes this task by using data on mortality to infer HIV prevalence in previous years: since those who die this year were infected in the past, current mortality and past prevalence are directly linked. In addition to generating data for the analysis of economic activity, this technique also provides new estimates of the level of the epidemic in Africa, and its time path. Using these new data, the project tests the relationship between HIV infections and exports in Africa, looking to see whether increases in exports actually make the HIV epidemic worse. If this is true, it argues for new policies, perhaps focusing prevention specifically on truck drivers and other migrants.
Finally, the project considers behaviors among individuals in the United States who are at risk for, or affected by, Huntington''s Disease (HD), which is a genetic, degenerative, neurological disorder. Specifically, the project looks for a relationship between individual HD status (at risk, affected, not at risk) and forward-looking behaviors. These behaviors include investment in education and job training, as well as choices about preventative health behaviors like mammograms and prostate cancer screening. Since individuals with HD (or at risk for HD) have a shortened lifespan in expectation, they may well devote fewer resources to costly behaviors that have long-term payoffs. In addition to providing insight into economic theories about the effect of life expectancy on forward-looking behaviors, this study may have implications for other individuals at risk for genetic diseases. As science advances and we increasingly have the ability to test for genetic risks, more and more people will be faced with the possibility of a shortened lifespan, and these issues of future investment may be important for a large fraction of the population.
