O1-S01.02 The incidence of genitalChlamydia trachomatisin a cohort of young Australian women

Abstract

BackgroundChlamydia is a sexually transmitted infection that can cause serious upper genital tract infections, however, in Australia there are limited population data for chlamydia. Understanding the incidence of chlamydia will be important in the design of a chlamydia screening program in Australia.MethodWomen aged 16–25 years were recruited from sexual health clinics (SHC) and general practice clinics (GP) in South-Eastern Australia and consented to participate in longitudinal study over a 12-month period. Participants were requested to send back questionnaires and self-collected vaginal swabs through the post which were tested for chlamydia.ResultsOverall, 1116 women were recruited from 29 clinics; with a 79% retention rate.C trachomatisprevalence at baseline was 4.9% (95% CI: 2.9% to 7.0%) and incidence rate for the 12-month study period was 4.4 per 100 women-years (95% CI: 3.3% to 5.9%). PrevalentC trachomatiswas associated with having hadC trachomatispreviously [AOR: 2.0 (95% CI: 1.1% to 3.9%)], increased numbers of sexual partners [AOR: 6.4 (95% CI: 3.6% to 11.3%)] and unprotected sex [AOR: 3.1 (95% CI: 1.0% to 9.5%)]. Antibiotic use and older age were protective against having a prevalent infection ([AOR: 0.4 (95% CI: 0.2% to 1.0%)] and [AOR: 0.9 (95% CI: 0.8% to 1.0%)] respectively) and an incident infection ([AHR: 0.1 (95% CI: 0.0% to 0.6%)] and [AHR: 0.4 (95% CI: 0.2% to 0.8%)] respectively). IncidentC trachomatiswas also associated with more partners [AHR: 4.0 (95% CI: 1.9% to 8.6%)]. More than 20% of women withC trachomatishad a re-infection during the study [20.3% (95% CI: 11.6% to 31.7%)] with an infection rate of 20.0 (95% CI: 11.9% to 33.8%) per 100 women years. The median chlamydia organism load was 1.4×105/5цl and the most common serovar identified was serovar E (51.9%).ConclusionChlamydia is a common STI in young Australian women, and an incidence of 4.9 per 100 women years for chlamydia suggests annual testing is appropriate for a chlamydia screening program. The high re-infection rate indicates the importance of partner notification and re-testing 3 months after treatment.

Repeat genitalChlamydia trachomatistesting rates in young adults in England, 2010

“…This is consistent with several other studies that have shown a higher risk of being diagnosed positive for chlamydia at follow-up following an initial positive test 2 5 6. This observation suggests that increasing re-testing after a positive chlamydia test could identify unresolved or repeat infections that may otherwise go untreated with yearly screening.…”

“…Thus a high proportion of individuals tested for chlamydia in England are likely to be eligible for re-testing within 1 year under current policy recommendations. Several studies have shown the higher risk of subsequently testing positive following a positive test,2 5 6 and a number of countries including USA,7 Canada,8 Australia9 and the Netherlands10 11 recommend repeat testing for individuals following a positive chlamydia test.…”

Incidence and risk factors associated with chlamydia in men who have sex with men: a cohort analysis of Victorian Primary Care Network for Sentinel Surveillance data

“…This is more than double the incidence of chlamydia infection in women aged 16e24 years (the group thought to be most affected by chlamydia), which was recently reported as 4.4/100 PY in Victoria (Walker J, Tabrizi S, Fairley C et al, unpublished data, 2012). 16 This is the first Australian study to have estimated chlamydia incidence among HIV-positive MSM. HIV-positive MSM in this study were two and a half times more likely to test positive for chlamydia compared with HIV-negative MSM.…”

Understanding trends in genitalChlamydia trachomatiscan benefit from enhanced surveillance: findings from Australia

“…Sexual health services' patients are more likely to seek care because of symptoms or perceived sexually transmitted infection risk, and thus, the positivity estimates of 12% are not an accurate measure of the burden of chlamydia in the general population (4.9% in young Australian women17). Genital symptom data are currently not collected as part of the ACCESS study.…”