An observational study in Syphilis, sponsored by Monash University. Recruiting at 9 sites in 4 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-04-03.
Sponsored by Monash University · Observational
How syphilis is transmitted between sexual partners is unclear. Asymptomatic detection i.e. detection of syphilis bacteria (Tp) from anatomical sites without lesions, in patients with syphilis infection, suggests that asymptomatic transmission from these sites may play a role. However, no existing studies have established whether the syphilis bacteria (Tp) detected was viable. This means it is not known if the bacteria at this anatomical site is alive and therefore able to transmit the infection. Further, studies have focused mostly on men who have sex with men, resulting in a lack of evidence regarding anal shedding in men-who-have-sex-with-women only and women (regardless of sexual behaviour), and no data on asymptomatic vaginal shedding in women. This study will explore:
126 studies on the registry are indexed under Syphilis; 34 are open to participants now.
This study's planned enrollment of 480 is above the median of 400 across 39 observational studies indexed under Syphilis.
Browse Syphilis studies →Monash University is the lead sponsor of 83 studies on the registry; 22 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Women and Men-Who-Have-Sex-With-Women-Only with early infectious syphilis
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
- 1. Any cis-woman, cis-MSW, or nonbinary individuals with a penis who have sex with women only, (who meet all other study criteria) 2. Aged ≥18 years of age, 3. At least one sexual partner in the last 12 months 4. One of either:
a. Untreated clinically suspected primary or secondary syphilis. i. Must have rash or lesion(s) clinically suggestive of early infectious syphilis infection.
ii. May have positive PCR result, positive Dark-ground Microscopy result, positive syphilis serology or positive point-of-care syphilis test, but these are not necessary at the time of enrolment.
b. Untreated early latent (no clinical signs indicative of primary or secondary syphilis) syphilis with positive syphilis serology or positive point-of-care test, and one or more of the following(11): i. A documented syphilis seroconversion within the prior 12 months. ii. A sustained (longer than 2 weeks) fourfold or greater increase in the titre in the prior 12 months in a person previously treated for syphilis.
iii. Unequivocal symptoms of primary or secondary syphilis within the prior 12 months.
iv. Contact in the prior 12 months with a sex partner who had untreated primary, secondary, or early latent syphilis.
v. Documented reactive nontreponemal and treponemal tests, and the only possible exposure occurred during the previous 12 months vi. RPR/VDRL titre >= 1:64 5. Be willing and able to complete study procedures, including physical examination 6. Receiving syphilis treatment on the day of recruitment 7. Have sufficient language proficiency to understand the requirements of the study 8. Provide as per individual site's local ethics requirements
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cis-women with suspected or confirmed primary syphilis infection
Other: No Intervention: Observational Cohort
Cis-women with suspected or confirmed secondary syphilis infection
Other: No Intervention: Observational Cohort
Cis-women with confirmed early-latent syphilis infection
Other: No Intervention: Observational Cohort
Men-who-have-sex-with-women-only with suspected or confirmed primary syphilis infection
Other: No Intervention: Observational Cohort
Men-who-have-sex-with-women-only with suspected or confirmed secondary syphilis infection
Other: No Intervention: Observational Cohort
Men-who-have-sex-with-women-only with confirmed early-latent syphilis infection
Other: No Intervention: Observational Cohort
No intervention: Observational study
Number of Biological Samples Testing Positive for Treponema pallidum DNA by PCR
This outcome measures the presence of Treponema pallidum (Tp) DNA in collected biological samples-including lesion swabs, blood, urine, saliva, and oral/anal/genital swabs-using a validated T. pallidum polymerase chain reaction (Tp PCR) assay. Data will be reported as the number and proportion of samples that test positive, stratified by: * sample type, * clinical stage of syphilis, * anatomical site (where applicable), * and participant characteristics relevant to the SOS Global protocol. No scale is used; this is a binary laboratory outcome (PCR positive / PCR negative).
Time frame: Samples are taken at time of consent - single visit study
Load of Treponema pallidum DNA in Positive Biological Samples by In-house Quantitative PCR (qPCR) assay
This outcome measures the load (copies/mL) of Treponema pallidum (Tp) DNA in collected biological samples-including lesion swabs, blood, urine, saliva, and oral/anal/genital swabs-using an in-house validated quantitative T. pallidum polymerase chain reaction (Tp qPCR) assay. Data will be reported as a comparison in load between anatomical sites and by clinical stage of syphilis.
Time frame: Samples are taken at time of consent - single visit study
Number of Treponema pallidum-Positive Samples Demonstrating Viable Organisms via Novel In-house Viability Assay
This outcome measures the viability of detected Treponema pallidum in PCR-positive biological samples. Viability is assessed using a novel in-house viability assay. Results will be summarised as the number and proportion of Tp PCR-positive samples that contain viable organisms, stratified by sample type and clinical/epidemiological variables specified in the SOS Global protocol. This outcome focuses on confirming whether Tp organisms in collected specimens are capable of establishing infection, rather than merely detecting genetic material. The viability assessment does not result in a continuous scale; it is a binary laboratory outcome (viable / non-viable).
Time frame: Samples are collected at time of consent - single study visit
Not enrolling at this site.
Not enrolling at this site.
Plan to share: Undecided — Request for data sharing will be considered on a case by case basis
No publications or documents are linked to this record.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Monash University