OBJECTIVES : To estimate trends in prevalence and incidence of syphilis, gonorrhea and chlamydia in
adult men and women in South Africa.
METHODS : The Spectrum-STI tool estimated trends in prevalence and incidence of active syphilis, gonorrhea
and chlamydia, fitting South African prevalence data. Results were used, alongside
programmatic surveillance data, to estimate trends in incident gonorrhea cases resistant to
first-line treatment, and the reporting gap of symptomatic male gonorrhea and chlamydia
cases treated but not reported as cases of urethritis syndrome.
RESULTS : In 2017 adult (15–49 years) the estimated female and male prevalences for syphilis were
0.50% (95% CI: 0.32–0.80%) and 0.97% (0.19–2.28%), for gonorrhea 6.6% (3.8–10.8%)
and 3.5% (1.7–6.1%), and for chlamydia 14.7% (9.9–21%) and 6.0% (3.8–10.4%), respectively.
Between 1990 and 2017 the estimated prevalence of syphilis declined steadily in
women and men, probably in part reflecting improved treatment coverage. For gonorrhea
and chlamydia, estimated prevalence and incidence showed no consistent time trend in
either women or men. Despite growing annual numbers of gonorrhea cases − reflecting population growth − the estimated number of first line treatment-resistant gonorrhea cases
did not increase between 2008 and 2017, owing to changes in first-line antimicrobial treatment
regimens for gonorrhea in 2008 and 2014/5. Case reporting completeness among
treated male urethritis syndrome episodes was estimated at 10–28% in 2017.
CONCLUSION : South Africa continues to suffer a high STI burden. Improvements in access and quality of
maternal, STI and HIV health care services likely contributed to the decline in syphilis prevalence.
The lack of any decline in gonorrhea and chlamydia prevalence highlights the need to
enhance STI services beyond clinic-based syndromic case management, to reinvigorate
primary STI and HIV prevention and, especially for women, to screen for asymptomatic
S1 File. Prevalence data and biomedical assumptions. Including:
A Table. Syphilis prevalence data from surveys, studies and routine ANC-based program screening, used in the Spectrum-STI estimation of adult syphilis prevalence in South Africa
With references: [7, 8, 19, 46, 50, 70–97].
B Table. Spectrum assumptions on proportion of episodes symptomatic, proportions of symptomatic
episodes treated, episode durations for treated and untreated episodes, and the resulting
treatment coverage-weighted average episode durations. With references: [10, 19, 38].
C Table. Gonorrhea and chlamydia prevalence data used, and adjustments for diagnostic test
performance and missing high-risk populations, and for chlamydia for age, in the Spectrum-
STI prevalence trend estimation for 15–49 year-old adults, South Africa. With references: [32,
46, 50, 51, 72, 77, 80, 81, 86, 91–93, 95, 98–116].
S2 File. Reported STI cases, and STI prevalences among women with Vaginal Discharge
Syndrome, South Africa.