Frequent Testing of Highly Sexually Active Gay Men Is Required to Control Syphilis

In the developed world, the incidence of syphilis among gay men has been increasing substantially. The authors developed an individual-based mathematical model describing syphilis transmission in a gay male population. They then used that model to simulate the anticipated relative impact of several screening and treatment interventions, targeting different at-risk groups with various coverage rates, frequency rates, and follow-up schedules.

Increasing the proportion of gay men who undergo testing each year would have "a relatively modest impact on syphilis incidence," the model predicted. "However, increasing the frequency of testing can have a large impact, with the prevalence of syphilis reduced substantially if individuals are tested every three months," according to the study. The results indicate that frequent screening of gay men who have large numbers of sex partners or who engage in group sex is a more efficient way of curbing syphilis epidemics. In addition, tracing the regular partners of infected persons is the most efficient intervention and can produce a significant epidemiological impact with relatively high rates of coverage.

"Increasing the frequency of testing and treatment are required to mitigate syphilis epidemics," the authors concluded. "Notifying and testing partners of infected men should occur where possible, but the high rates required to reverse epidemic trends are likely to be infeasible. Contact tracing should be a secondary priority that is coupled with increases in the frequency of testing in the population. Encouraging testing among men not previously tested for syphilis is also recommended."