• sexually transmitted disease
• prevention

This conference has brought together the world's leading researchers and experts to assess the present and future of sexually transmitted infection (STI) control using a new paradigm. In light of the ongoing massive HIV sexual epidemic and the known multiplicative impact of other STIs, fresh and intensified approaches are needed. Since 1997, reportable bacterial STIs have been increasing in Canada after years of decline.^{1, 2} Likewise, the most recent Canadian HIV incidence estimates show an increase in men who have sex with men (MSM).^{3, 4} Thus the findings of this conference are vital to the current Canadian STI control efforts.

The United States, United Kingdom, and Australia have established broad national health objectives.^5–7 In the area of sexually transmitted infections, Canada has set national goals.⁸ These goals serve to focus attention and build consensus among professionals, policymakers, non-governmental organisations (NGOs), and the public in addressing the hidden STI epidemic. They provide measurable outcomes with which to evaluate the efficiency and effectiveness of public health actions for resource allocations.

Wasserheit and Aral⁹ proposed that an STI epidemic begins with a growth phase involving individuals of both the maintenance networks of primarily high socioeconomic status (SES) and of the mainly low SES spread networks. It then evolves through a plateau (hyperendemic phase), and then a decline phase. Eventually a new equilibrium is reached (endemic phase) in which the STI becomes sequestered: the mainly hard to reach, marginalised spread network.

To develop strategies for national goals, it is important to modify our surveillance strategies and the targeting of interventions as the epidemic evolves through these different phases. Infected individuals from higher SES groups have greater access to health care and educational resources. Thus in earlier phases routine surveillance is more likely to detect these cases and intervention can then follow. Concurrently, to reach the marginalised groups enhanced surveillance and intervention approaches must be employed and then expanded in later phases as the proportion of this group increases.

For example, in the hyperendemic phase, a clinic based gonorrhoea screening strategy may detect a large number of these infected higher SES individuals, but be relatively ineffectual in reducing the size of the infected disadvantaged subpopulations. Concurrently, a mobile outreach van, involving peer risk reduction counselling, can be used to target these individuals. In Canada, as the gonorrhoea epidemic progressed past the hyperendemic phase, resources were redirected from the higher SES groups to those in which the disease remains entrenched.

Unlike bacterial STIs, routine national surveillance is not conducted for viral STIs in Canada. For example, while the United States' national health and nutrition examination surveys (NHANES) determined an increase in HSV-2 seroprevalence,¹⁰ in Canada such longitudinal population based data have not been collected. Only when such information is available in Canada can we determine the phase to which a viral STI epidemic has evolved and develop phase specific strategies. One important outcome of our national goal strategies has been the emergence of the first baseline Canadian population data for HSV and human papilloma virus.^11–15

Although the evolution of phases is often considered to progress only in the forward direction, under destabilising conditions epidemics can regress to earlier phases. For example, with the flourishing of internet sex chat rooms and the availability of potent anti-HIV drugs, among other factors, Canada is now facing a resurgence of bacterial STIs even among those already infected with HIV.^{1, 16} To meet these challenges, strategies for achieving national goals must be adapted accordingly. The phase specific approach allows new insights and opportunities to be more successful in reducing the burden and sequelae of STIs in Canada in the future.