In 2002, the prevailing view was that preventive strategies, rather than the provision of highly active antiretroviral therapy (HAART), were the only feasible way to control the spread of HIV infection.1 Antiretroviral treatment is now cheaper, thanks to initiatives from the pharmaceutical industry and generic manufacture, and its wider availability encourages more people to seek HIV testing. In line with the “3 by 5”strategy, the World Health Organization aims to provide HAART for three million people by the end of 2005 while continuing to promote prevention. Provision of treatment may be hindered by availability or infrastructural capacity. To make a sustainable impact on the global epidemic of HIV infection, investment in prevention research, including biomedical prophylaxis, remains paramount. Various government campaigns aimed at increasing knowledge and modifying high risk behaviour have been temporally associated with reduced incidence and prevalence of HIV infection in a few countries, notably Thailand and Uganda.2 It remains unclear, however, whether these events are causally …