O1-S01.03 High yield in reinfections during a chlamydia screening programme when automatically sending testkits after 6 months to previously infected

Background Reinfections remain challenging in the control of Chlamydia trachomatis (Ct). In a systematic internet-based Ct Screening programme (CSI) in the Netherlands, all Ct-positive participants automatically received a test kit after 6 months to facilitate discovery of reinfections. Determinants for reinfection for two screening rounds, treatment and partner notification are discussed. Methods CSI-home-based testkits can be requested online after register based postal invitation. Infected participants get a referral letter for their health provider to get treatment for themselves and their current partner; expartners can be alerted by the participant and request a test kit via the website. Participants fill in a questionnaire on sexual behaviour voluntarily. Ct-positives answer questions about treatment and partner notification 10 days after checking their results. Infected participants who do not check their result online receive it by postal letter. After 6 months retest kits are automatically sent to previously infected participants. Results Overall, 3185 participants (4.1%) tested positive; 7% of Ct-positives did not check their result online and received a postal letter. The majority (86%) of Ct-positive participants who answered the treatment questionnaire (response 43%) was treated within 2 weeks after checking their result online; 80% of those with a current relationship reported their partner had also been treated and 16% of those with past relationships notified ex-partners via the website. One third of the ex-partners participated, 28% of whom were Ct-positive. After 6 months, 3055 participants received a retest kit and 66% responded. The reinfection rate was 8.8%. Results of the questionnaire revealed 75% of retest-positives had been treated for the initial infection and 70% had had their partner treated, while these proportions were 87% and 80% among retest-negatives. At higher risk for reinfections were young people (