Syphilis prevalence among key populations (A, B, D)

Export Indicator

Prevalence of syphilis in specific key populations
What it measures

This indicator is divided into three sub-indicators:

A. Syphilis prevalence among sex workers.

B. Syphilis prevalence among gay men and other men who have sex with men.

D. Syphilis prevalence among transgender people.

What it measures:

Progress towards reducing syphilis prevalence among key populations


The prevalence of syphilis is typically much higher in key populations than in the general population. Reducing the prevalence of syphilis among key populations is important for the health of the population and also a critical measure of the national-level response to syphilis.

The increasing use of rapid tests for testing (screening) individuals for syphilis has increased access to syphilis testing in settings that were previously without capacity. As a result, this indicator has been expanded to syphilis prevalence rather than focusing solely on active syphilis.

Testing for syphilis in key populations is a component of second-generation HIV surveillance.


Number of people in a key population who test positive for syphilis


Number of people in a key population tested for syphilis



Method of measurement

This indicator is calculated using data from syphilis tests conducted among respondents in sentinel site(s) or participants in biobehavioural surveys or regular sexually transmitted infection screening services. The sentinel surveillance sites used for calculating this indicator should remain constant to allow for tracking changes over time.

Screening may be done with either a nontreponemal test (e.g., venereal disease research laboratory [VDRL] or rapid plasma reagin [RPR]) or a treponemal test (e.g., Treponema pallidum haemagglutination assay [TPHA], Treponema pallidum particle agglutination assay [TPPA], enzyme immunoassay or rapid treponemal test). While nontreponemal serologic tests are sensitive, they lack specificity and can result in false positive cases. Treponemal tests are more specific but cannot differentiate between current and past infection or treated and untreated infection. For the purpose of this indicator (intended to measure seropositivity), reporting positivity based on a single test result is acceptable. However, if both treponemal and nontreponemal test results for an individual person are available, then syphilis positivity should be defined as having positive results on both tests. Countries are required to report the testing algorithm used to determine positivity so prevalence estimates can be adjusted to look at trends over time and generate regional and global estimates.

Measurement frequency

Annual (programme data) or every two years (biobehavioural survey).


A, B, D: age (<25 and 25+ years).

A: gender (male, female and transgender).

D: gender (transman, transwoman and other).

Additional information requested

Please document in the comments section if the testing algorithm has changed since the last Global AIDS Monitoring report.

Please comment on the extent to which the data are deemed representative of the national population

Strengths and weaknesses

Understanding how the sampled populations relate to any larger populations sharing similar high-risk behaviour is critical to interpreting this indicator. Trends in syphilis prevalence among key populations in the capital city provide a useful indication of the performance of HIV and sexually transmitted infection prevention programmes in that city, but they may not be representative of the situation in the country as a whole. The addition of new sentinel sites increases the sample's representativeness and therefore provides a more robust point estimate of syphilis prevalence. However, adding new sentinel sites reduces the comparability of values over time. As such, any changes in number of sites providing data needs to be documented in the comments section.

Surveys exclusively covering transgender people are rare. Most data for transgender communities are drawn from surveys of gay men and other men who have sex with men or sex workers. The risk environment reported for most transgender communities is high, placing transgender women at especially high risk of acquiring a sexually transmitted infection and of transmitting that infection. If transgender women are respondents in surveys of sex workers, include the data with sex workers as a disaggregation. If transgender people are respondents in surveys of gay men and other men who have sex with men, include the data under the transgender tab.

Testing using both nontreponemal and treponemal tests enhances the likelihood that the reported numbers of positive tests represent active infection. Some countries, however, only have information for one test type. Please note in the comment fields if syphilis testing practices have changed, as this will need to be considered when interpreting the disease trends.

Further information

Consolidated guidelines on HIV, viral hepatitis and STI prevention, diagnosis, treatment and care for key populations. Geneva: World Health Organization; 2022. (