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

Background: Despite the availability of safe and effective treatment, infec tion with bacterial sexually transmitted diseases persists at a high preval ence in many populations. Goal: To review the difficulties of parameter estimation when a cure is rea dily available and to explore the impact of different treatment and screeni ng strategies that might maximize the benefits of using available treatment s. Study Design: A standard deterministic model for the spread of a bacterial sexually transmitted disease that causes symptomatic and asymptomatic infec tions, in which the population is stratified according to sex and sexual ac tivity, is further stratified into two host groups to enable the modeling o f different treatment and screening strategies. Results: In the presence of a core group, if an infection has a high transm ission probability, then screening for asymptomatic infections has a short- lived benefit. Repeated screening is slightly better if it is not restricte d to a fraction of the at-risk population, but targeting of high-risk group s should be effective. Screening to treat asymptomatic infections in men co uld 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 achie ved 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 s hould be worthwhile.