Risky sexual behavior, testing and new HIV treatments

Beyond changes in number of partners by the HIV+, the spread of HIV stems from the type of sex chosen, the behaviors of susceptibles and the diminished risk of HIV transmission when HIV patients are under HAART (Blower, Gershengorn and Grant, 2000). [...] The optimal level of risk is determined by the tradeoff between the perceived benefits of risky sex (relative to safer sex) and the expected cost to be infected, which depends on one’s number of risky sexual exposures, the overall prevalence rate (taken as given), and the availability of treatment. [...] One of the fundamental results of economic epidemiology is that the optimal number of risky exposures decreases with the prevalence of the disease. [...] Second, the new drugs extend the lives and improve the quality of life of HIV+ individuals, which implies an increase in the proportion of those present in the market for risky exposures. [...] An analogy would be the standard end product of a decrease in the wage on the competitive equilibrium of workers hired: as the wage falls, the demand for labor increases but the price of output falls as well, which results in less of an increase in labor than would have been the case had output price remained constant.