Epidemiology and control of curable sexually transmitted diseases - Opportunities and problems

Background: Despite the availability of safe and effective treatment, infection with bacterial sexually transmitted diseases persists at a high prevalence in many populations. Goal: To review the difficulties of parameter estimation when a cure is readily available and to explore the impact of different treatment and screening strategies that might maximize the benefits of using available treatments. Study Design: A standard deterministic model for the spread of a bacterial sexually transmitted disease that causes symptomatic and asymptomatic infections, in which the population is stratified according to sex and sexual activity, is further stratified into two host groups to enable the modeling of different treatment and screening strategies. Results: In the presence of a core group, if an infection has a high transmission probability, then screening for asymptomatic infections has a short-lived benefit. Repeated screening is slightly better if it is not restricted to a fraction of the at-risk population, but targeting of high-risk groups should be effective. Screening to treat asymptomatic infections in men could be beneficial if a substantial fraction of cases remain asymptomatic, Conclusions: After the initial gains achieved through treating symptomatic infections, further reductions in the prevalence of infections can be achieved by finding asymptomatic infections. However, these gains are difficult to achieve, especially in the case of gonorrhea. Because men are likely to have an asymptomatic chlamydial infection, screening of men for chlamydia should be worthwhile.