HIV Testing: a Trojan Horse?

The consequences of HIV testing are unclear. Some infected individuals, assuming they behave selfishly, would tend to increase their number of partners. Meanwhile, non-infected ones or those ignorant of their status would decrease theirs, the result of which, on the equilibrium level of infection, is uncertain. Simulations from a simple dynamic model show how to generate the Philipson-Posner conjecture, i.e., that disclosure of HIV status may result in higher disease prevalence. In this benchmark case, testing would also lower welfare. Those results, however, appear to be fragile. In particular, very little altruism seems needed for testing to become beneficial, and the public health literature tells us that a large proportion of individuals behave altruistically when tested positive and appropriately counseled. Beyond the mere availability of testing, the findings further suggest combining existing prevention measures with universal or mandatory testing to help eradicate the disease.