Putting the magic in magic bullets: top three global priorities for sexually transmitted infection control

INTRODUCTION Setting practical priorities for sexually transmitted infection (STI) control is a balance between idealism and pragmatism. Infections transmitted through unsafe sex (chlamydia, gonorrhoea, syphilis, HIV, hepatitis B and human papillomavirus (HPV) infections) rank in the top five causes of the global burden of disease. Their distribution in populations is driven by a complex mixture of individual behaviours, social and community norms and societal and historical context. Ideally, we would be able to reduce exposure to unsafe sex to its theoretical minimum level of zero and thus eliminate a significant proportion of the current global burden of disease, particularly in resourcepoor settings. Ideally, we would have ‘magic bullets’ for diagnosing and preventing STI in addition to specific antimicrobial agents for specific infections. Arguably, we have ‘bullets’ that work at the individual level; highly accurate diagnostic tests and highly efficacious vaccines, antimicrobial agents and preventive interventions. Introducing them into populations to achieve similarly high levels of effectiveness has been more challenging. In practice, the ‘magic’ in the magic bullet can be seen as overcoming the barriers to sustainable implementation in partnerships, larger sexual networks and populations (figure 1). We have chosen three (pragmatic) priorities for interventions that we believe could be implemented and scaled up to control STI other than HIV/AIDS. We present these starting with the partnership and moving up to the population level.