Comparative model-based analysis of screening programs for Chlamydia trachomatis infections

The design of a screening program for asymptomatic genital infections with Chlamydia trachomatis, requires decisions about which sex or age group should be targeted and whether partner referral should be included in the program. To investigate the effects of various screening programs on the prevalence and incidence of asymptomatic C. trachomatis infections in women, in May 1996 to April 1997 in Bilthoven, the Netherlands, the authors used a stochastic simulation model for C. trachomatis transmission in an age-structured, heterosexual population with a sexually highly active core group. Different screening scenarios were implemented over a time period of 10 years. Prevalence, incidence, and the fraction of infected persons found by partner referral were computed. Through screening of men and women between ages 15 and 24 years (baseline scenario), the prevalence of asymptomatic infections in women could be reduced from 4.2% to 1.4% in 10 years. Increasing the age range of screening up to ages 29 or 34 years led to prevalences of 0.4% and 0.06%, respectively, after 10 years. About 28% of all infected persons were found via partner referral. There are considerable indirect positive effects of screening on those population groups that are not included in the screening because of the reduced risk of becoming infected. Partner referral contributes substantially to prevalence reduction.