Infectious syphilis in women and heterosexual men in major Australian cities: sentinel surveillance data, 2011-2019

Syphilis testing, incidence, and reinfection among gay and bisexual men in Australia over a decade spanning HIV PrEP implementation: an analysis of surveillance data from 2012 to 2022

Background

Gay and bisexual men (GBM) remain overrepresented among syphilis diagnoses in Australia and globally. The extent to which changes in sexual networks associated with HIV pre-exposure prophylaxis (PrEP) and treatment as prevention (TasP) may have influenced syphilis transmission among GBM at the population-level is poorly understood. We describe trends in syphilis testing and incidence among GBM in Australia over eleven years spanning widespread uptake of HIV PrEP and TasP.

Methods

We analysed linked clinical data from GBM aged 16 years or older across a sentinel surveillance network in Australia from January 1, 2012, to December 31, 2022. Individuals with at least two clinic visits and with at least two syphilis tests during the observations period were included in testing and incidence analyses, respectively. Annual rates of testing and infectious syphilis incidence from 2012 to 2022 were disaggregated by HIV status and PrEP use (record of PrEP prescription; retrospectively categorised as ever or never-PrEP user). Cox regression explored associations between demographics, PrEP use and history of bacterial sexually transmissible infections (STIs) and infectious syphilis diagnosis.

Findings

Among 129,278 GBM (mean age, 34.6 years [SD, 12.2]) included in testing rate analyses, 7.4% were living with HIV at entry and 31.1% were prescribed PrEP at least once during the study period. Overall syphilis testing rate was 114.0/100 person-years (py) and highest among GBM with HIV (168.4/100 py). Syphilis testing increased from 72.8/100 py to 151.8/100 py; driven largely by increases among ever-PrEP users. Among 94,710 GBM included in incidence analyses, there were 14,710 syphilis infections diagnosed over 451,560 person-years (incidence rate = 3.3/100 py). Syphilis incidence was highest among GBM with HIV (6.5/100 py), followed by ever-PrEP users (3.5/100 py) and never-PrEP users (1.4/100 py). From 2012 to 2022, syphilis incidence increased among ever-PrEP users from 1.3/100 py to 5.1/100 py, and fluctuated between 5.4/100 py and 6.6/100 py among GBM with HIV. In multivariable Cox regression, previous syphilis diagnosis (adjusted hazard ratio [aHR] = 1.98, 95% CI = 1.83-2.14), living with HIV (aHR = 1.83, 95% CI = 1.12-1.25) and recent (past 12 m) prescription of PrEP (aHR = 1.78, 95% CI = 1.61-1.97) were associated with syphilis diagnosis.

Interpretation

Syphilis trends between GBM with HIV and GBM with evidence of PrEP use have converged over the past decade in Australia. Our findings recommend targeting emergent syphilis control strategies (e.g. doxycycline post-exposure prophylaxis) to GBM with prior syphilis diagnoses, using HIV PrEP or who are living with HIV.

Funding

Australian Department of Health and Aged Care, National Health and Medical Research Council.

Notification rates for syphilis in women of reproductive age and congenital syphilis in Australia, 2011-2021: a retrospective cohort analysis of national notifications data

OBJECTIVES

To estimate notification rates for infectious syphilis in women of reproductive age and congenital syphilis in Australia.

STUDY DESIGN

Retrospective cohort study; analysis of national infectious syphilis and enhanced congenital syphilis surveillance data.

SETTING, PARTICIPANTS

Women aged 15-44 years diagnosed with infectious syphilis, and babies with congenital syphilis, Australia, 2011-2021.

MAIN OUTCOME MEASURES

Numbers and rates of infectious syphilis notifications, by Indigenous status and age group; numbers and rates of congenital syphilis, by Indigenous status of the infant; antenatal care history for mothers of infants born with congenital syphilis.

RESULTS

During 2011-2021, 5011 cases of infectious syphilis in women aged 15-44 years were notified. The notification rate for Aboriginal and Torres Strait Islander women rose from 56 (95% confidence interval [CI], 45-65) cases per 100 000 in 2011 to 227 (95% CI, 206-248) cases per 100 000 population in 2021; for non-Indigenous women, it rose from 1.1 (95% CI, 0.8-1.4) to 9.2 (95% CI, 8.4-10.1) cases per 100 000 population. The notification rate was higher for Aboriginal and Torres Strait Islander women than for non-Indigenous women (incidence rate ratio [IRR], 23.1; 95% CI, 19.7-27.1), lower for 15-24- (IRR, 0.7; 95% CI, 0.6-0.9) and 35-44-year-old women (IRR, 0.6; 95% CI, 0.5-0.7) than for 25-34-year-old women, and higher in remote regions than in major cities (IRR, 2.7; 95% CI, 2.2-3.8). During 2011-2021, 74 cases of congenital syphilis were notified, the annual number increasing from six in 2011 to a peak of 17 in 2020; the rate was consistently higher among Aboriginal and Torres Strait Islander infants than among non-Indigenous infants (2021: 38.3 v 2.1 per 100 000 live births). The mothers of 32 infants with congenital syphilis (43%) had not received antenatal care.

CONCLUSIONS

The number of infectious syphilis notifications for women of reproductive age increased in Australia during 2011-2021, as did the number of cases of congenital syphilis. To avert congenital syphilis, antenatal screening of pregnant women, followed by prompt treatment for infectious syphilis when diagnosed, needs to be improved.

Syphilis Screening Among Young Black Men Who Have Sex With Women in New Orleans, LA

BACKGROUND

Current US syphilis screening focuses on men who have sex with men (MSM), because of the increased risk of infection in their sexual networks, and on pregnant people, because of complications associated with congenital syphilis. However, screening for men who have sex with women (MSW) who are at increased risk of syphilis is also recommended. Factors associated with syphilis testing and positivity were assessed among young, Black MSW.

METHODS

Data from the Check It study-a seek, test, and treat study for chlamydia in New Orleans, LA, among Black MSW aged 15 to 26 years-were used. Survey data were used to elicit self-reported syphilis testing, self-reported testing results, and sociodemographic and behavioral factors associated with these 2 outcomes.

RESULTS

Per the Centers for Disease Control and Prevention, all men in the study were recommended for syphilis screening because of their age, race, and geographic location. Of the 1458 men included, 272 (18.7%) reported ever having been syphilis tested, 267 men reported their results, and 23 (8.6%) reported testing positive. In logistic regression, older age (odds ratio [OR], 1.21 per year older; P < 0.001), prior Chlamydia trachomatis , Neisseria gonorrhoeae , and/or HIV testing (OR, 50.32; P < 0.001), and younger age at sexual debut (0.90 per year older, P = 0.005) were significantly associated with prior syphilis testing. In addition, testing positive for C. trachomatis and/or N. gonorrhoeae during the study was significantly associated with a history of syphilis positivity (OR, 3.08; P = 0.031).

CONCLUSIONS

Although syphilis testing was associated with factors that might increase the risk of acquisition, only 19% of individuals meeting Centers for Disease Control and Prevention testing recommendations had ever been screened.

Increased syphilis testing and detection of late latent syphilis among women after switching from risk-based to opt-out testing strategy in an urban Australian sexual health clinic: a retrospective observational study

Background

The Melbourne Sexual Health Centre (MSHC) implemented an opt-out syphilis test for women in December 2017. We aimed to examine the differences in syphilis testing uptake and confirmed syphilis cases among women after switching from risk-based to opt-out testing strategies.

Methods

This was a retrospective study examining all women attending the MSHC for the first time in periods of risk-based testing (2015-2017) and opt-out testing (2018-2020). We calculated the proportion of women who tested for syphilis and the proportion of women with confirmed syphilis in each period. A chi-square test was performed to determine the differences in proportion between the risk-based testing and opt-out periods.

Findings

A total of 27,481 women (i.e. 13,059 in the risk-based testing period and 14,422 in the opt-out period) were included in the final analysis, and the mean age was 26.8 years (standard deviation = 6.9). The proportion of women who were tested for syphilis at their first consultation increased from 52.8% (6890/13,059) in the risk-based testing period to 67.4% (9725/14,422) in the opt-out period (p < 0.0001). Syphilis positivity did not differ between the two periods (0.48% [33/6890] vs 0.71% [69/9725], p = 0.061) but late latent causes increased from 36.4% [12/33] to 60.9% [42/69] (p = 0.033).

Interpretation

The opt-out testing strategy increased syphilis testing among women with increased detection of asymptomatic late latent syphilis. The opt-out syphilis testing strategy is beneficial in sexual health services. Health education and awareness may be required to improve syphilis testing uptake.

Funding

National Health and Medical Research Council.

The Reemergence of Syphilis Among Females of Reproductive Age and Congenital Syphilis in Victoria, Australia, 2010 to 2020: A Public Health Priority

BACKGROUND

Syphilis notifications in Victoria, Australia, have been increasing over the past decade, with an increase in infectious syphilis (syphilis of less than 2 years in duration) cases in females of reproductive age and an associated reemergence of congenital syphilis (CS). Before 2017, there had been 2 CS cases in the preceding 26 years. This study describes the epidemiology of infectious syphilis among females of reproductive age and CS in Victoria.

METHODS

Routine surveillance data provided by mandatory Victorian syphilis case notifications were extracted and grouped into a descriptive analysis of infectious syphilis and CS incidence data from 2010 to 2020.

RESULTS

In 2020, infectious syphilis notifications in Victoria were approximately 5 times more than 2010 (n = 289 in 2010 to n = 1440 in 2020), with a more than 7-fold rise among females (n = 25 in 2010 to n = 186 in 2020). Females made up 29% (n = 60 of 209) of Aboriginal and Torres Strait Islander notifications occurring between 2010 and 2020. Between 2017 and 2020, 67% of notifications in females (n = 456 of 678) were diagnosed in low-caseload clinics, at least 13% (n = 87 of 678) of all female notifications were known to be pregnant at diagnosis, and there were 9 CS notifications.

CONCLUSIONS

Cases of infectious syphilis in females of reproductive age and CS are on the rise in Victoria, necessitating sustained public health action. Increasing awareness among individuals and clinicians, and health system strengthening, particularly targeting primary care where most females are diagnosed before pregnancy, are required. Treating infections before or promptly during pregnancy and undertaking partner notification and treatment to reduce risk of reinfection are critical to reducing CS cases.