Early syphilis infection among men who have sex with men

Syphilis caused by the spirochete Treponema pallidum subspecies pallidum is a sexually transmitted infection with worldwide increasing incidence. Although effective treatment for syphilis is known, late complications and congenital malformations still occur. In high-income countries syphilis is predominantly detected in men who have sex with men (MSM). This thesis aims to provide more insight on effective measures for prevention of syphilis in MSM, to improve diagnostics and increase the knowledge on the molecular diversity at different body locations and in different syphilis stages.
In chapters 2 and 3 we developed a syphilis awareness campaign including a symptom-based risk score to identify individuals with syphilis. In chapter 4, we assessed whether there are differences between HIV-negative MSM and HIV-positive MSM with infectious syphilis regarding their history of previous syphilis episodes, disease stage, non-treponemal titer of initial and repeat episodes, and the titer response 6 and 12 months post-treatment. In chapter 5, we described the occurrence of treatment failure with short-acting benzylpenicillin. In chapter 6, we investigated whether an unconfirmed CLIA seroconversion indicates early incubating syphilis or a biological false positive result. In chapters 7 and 8, we detected T. pallidum DNA by PCR in various sample types from different anatomical locations in patients with early syphilis. Furthermore, we found intrapatient homogeneity within patients with early syphilis. In chapter 9, we evaluated a home-based self-collection sampling strategy using dried blood spots for STI testing and measuring creatinine concentration.