oa Symptomatic treatment approach does not appear to be effective in controlling Chlamydia trachomatis transmission

[Background] Chlamydia trachomatis (CT) is one of the most common bacterial sexually transmitted infections (STIs) worldwide, and is a major cause of pelvic inflammatory disease, infertility, and ectopic pregnancy. A recent study has found larger than expected prevalence of CT in Qatar, with a prevalence of about 5% among women attending primary health-care centers. The driver of such higher than expected prevalence is not clear. We examined whether the lack of screening programs for CT could contribute to explaining this level of prevalence. [Method] We constructed a mathematical model to examine the public health impact of different CT treatment approaches. The model was parameterized by the prevalence of CT in Qatar along with state of the art empirical evidence of CT natural history and transmission. The population was divided into different risk and age groups, and a mixing matrix was introduced to describe the mixing between these groups. The impact of treatment was assessed at endemic equilibrium. Univariate sensitivity analyses were conducted. [Results] Nearly 63% of CT infections in the population were asymptomatic. A symptomatic treatment approach, where 90% of symptomatic cases were treated, reduced CT prevalence by only 6.5%. An opportunistic screening program, where 20% of the population was screened annually for CT, reduced the prevalence by 36%. Routine screening program, where 50% of the population was screened annually for CT, reduced the prevalence by 93%. The large impact of screening on CT transmission was driven not only by the diagnosis of asymptomatic infections and treating them, but also by reducing effectively the duration of the infectious period during which infected persons can transmit the infection to other individuals. [Discussion] Our results suggest that a key contributor to the higher than expected prevalence of CT in Qatar, is the non-availability of CT-specific screening programs to detect and treat asymptomatic CT infection, such as those available in West Europe and North America. Current programs that focus on treatment of syndromic cases are missing the majority of cases. The undiagnosed infections are driving further transmissions, and a larger CT prevalence. Opportunistic targeted screening could be a meaningful starting point for CT screening programs in Qatar, with potentially routine Pap smear testing as an entry point. Our findings indicate the utility of developing STI-specific programs in Qatar as part of the large expansion of health care services in this country. Detecting CT infections and linking them with appropriate treatment channels could alleviate an unnecessary disease burden and its consequences in the population.