Rates and Correlates of Syphilis Reinfection in Men Who Have Sex with Men

Impact of screening and doxycycline prevention on the syphilis epidemic among men who have sex with men in British Columbia: a mathematical modelling study

Background

Men who have sex with men (MSM) in British Columbia (BC) are disproportionately affected by infectious syphilis and HIV. In this study, we developed a co-interaction model and evaluated the impact and effectiveness of possible interventions among different MSM subgroups on the syphilis epidemic.

Methods

We designed a deterministic compartmental model, which stratified MSM by HIV status and HIV pre-exposure prophylaxis (HIV-PrEP) usage into (1) HIV-negative/unaware MSM (HIV-PrEP not recommended, not on HIV-PrEP), (2) HIV-negative/unaware MSM with HIV-PrEP recommended (not on HIV-PrEP), (3) HIV-negative/unaware MSM actively on HIV-PrEP, and (4) MSM diagnosed with HIV. We estimated the effect of scaling up syphilis testing frequency from Status Quo to six-, four-, and three-months, increasing the percentage of MSM using doxycycline prevention (Doxy-P) to 25%, 50%, and 100% of the target level, and a combination of both among subgroups (2)-(4). We also assessed the impact of these interventions on the syphilis incidence rates from 2020 to 2034 in comparison to the Status Quo scenario where no intervention was introduced.

Findings

Under the Status Quo scenario, with the expansion of the HIV-PrEP program to improve syphilis testing, the syphilis incidence rate was estimated to peak at 16.1 [Credible Interval (CI):14.2-17.9] per 1,000 person-years (PYs) in 2023 and decrease to 6.7 (CI:3.8-10.9) per 1,000 PYs by 2034. The syphilis incidence rate in 2034 was estimated at 0.7 (0.3-1.3) per 1,000 PYs if MSM diagnosed with HIV could be tested every four months, and at 1.5 (0.7-3.0) per 1,000 PYs if HIV-negative/unaware MSM actively on HIV-PrEP could be tested every three months. By achieving 100% of the target coverage of Doxy-P, the syphilis incidence rate was estimated at 1.4 (0.5-3.4) if focusing on MSM diagnosed with HIV, and 2.6 (1.2-5.1) per 1,000 PYs if focusing on HIV-negative/unaware MSM actively on HIV-PrEP. Under the combined interventions, the syphilis incidence rate could be as low as 0.0 (0.0-0.1) and 0.8 (0.3-1.8) per 1,000 PYs, respectively.

Interpretation

The HIV-PrEP program in BC plays a crucial role in increasing syphilis testing frequency among high-risk MSM and reducing syphilis transmission among this group. In addition, introducing Doxy-P can be an effective complementary strategy to minimize syphilis incidence, especially among MSM diagnosed with HIV.

Funding

This work was funded by the Canadian Institutes of Health Research.

Clinical and immunological characteristics of HIV/syphilis co-infected patients following long-term antiretroviral treatment

Objective

This study aims to analyze the efficacy of anti-syphilis treatment and the impact of syphilis events on HIV virology and immunology in HIV/syphilis co-infected patients on long-term antiretroviral therapy (ART) and to investigate the incidence and factors of syphilis recurrence/re-infection/serofast state. The insights derived from this investigation can potentially guide strategies for preventing and managing syphilis and AIDS.

Methods

A retrospective case-control study was conducted at the AIDS clinic of Peking Union Medical College Hospital from January 2003 to December 2022. The study involved 86 HIV/syphilis co-infected patients and 86 HIV mono-infected patients matched based on age, baseline CD4 + T cell counts, and viral load. We examined the clinical characteristics of HIV/syphilis co-infected patients, evaluated the efficacy of anti-syphilis treatment, and analyzed the dynamic changes in HIV virology and immunology. The Generalized Estimating Equations (GEE) model investigated the factors associated with HIV/syphilis co-infection and syphilis recurrence/reinfection/serofast state.

Results

Syphilis serofast state was observed in 11.6% (10/86) of HIV/syphilis co-infected patients after treatment, and 33.7% (29/86) had syphilis recurrence or re-infection. The overall effectiveness of syphilis treatment stood at 76.8% (63/82). Notably, the effectiveness of syphilis treatment displayed a significant correlation with baseline syphilis titers exceeding 1:128 (p = 0.003). Over the 10-year follow-up period on ART, the HLA-DR + CD8+/CD8 + % levels in the HIV/syphilis co-infected group were markedly higher than those in the HIV mono-infected group (p < 0.05). However, no significant differences were observed between the two groups regarding HIV viral load, CD4+ T cell counts, CD8+ T cell counts, CD4/CD8 ratio, and CD38 + CD8+/CD8 + % (p > 0.05). GEE analysis model revealed that elevated HLA-DR + CD8+/CD8 + % levels were associated with HIV/syphilis co-infection (OR = 1.026, 95% CI = 1.007-1.046; p = 0.007) and syphilis recurrence/reinfection/serofast state (OR = 1.036, 95% CI = 1.008-1.065; p = 0.012).

Conclusion

While HIV/syphilis co-infected patients typically receive adequate treatment, the incidence of syphilis recurrence and reinfection remain notably elevated. A heightened HLA-DR + CD8+/CD8+ % is a notable risk factor for HIV/syphilis co-infection and syphilis recurrence/reinfection/serofast state. Therefore, it is advisable to reinforce health education efforts and ensure regular follow-ups for people living with HIV undergoing ART to monitor syphilis infection or increased risk of syphilis infection.

Sexually Transmitted Infections and the Risk of Reinfection Within 12 Months: A Population-Based Cohort

BACKGROUND

Chlamydia, gonorrhea, and syphilis are common sexually transmitted infections that disproportionately affect specific groups in New Zealand (NZ). Predictors of reinfection are not well studied in NZ but could inform public health strategies to decrease sexually transmitted infection (STI) incidence.

METHODS

New Zealand-wide chlamydia, gonorrhea, and syphilis cases during 2019 were identified using nationally collected data. Cases were followed-up to identify reinfection with the same STI within 12 months of initial infections. Logistic regression models were used to identify predictors for each STI reinfection.

RESULTS

Determinants identified for increased odds of chlamydia reinfection were age groups 16-19 and 20-24 years, females, Māori and Pacific peoples, cases in the Northern region, and cases with at least one test before the initial infection. Age 40 years and older was associated with lower odds of gonorrhea reinfection, as was being of Asian ethnicity, living in Midland or Southern regions, and reporting heterosexual behavior. Region was the only statistically significant predictor for syphilis reinfection, with higher odds of reinfection for people living in the Central region.

CONCLUSIONS

Our findings reflect disproportionate STI rates for some groups in NZ, with younger age groups, Māori and Pacific peoples, men who have sex with men, and people living in the Northern region experiencing higher odds of reinfection. Groups identified with higher odds for reinfection require increased access to culturally responsive health services to treat, understand, and prevent possible reinfection. Changes to current public health strategies could include culturally specific behavioral counseling, and improvements to and adherence to effective contract tracing.

Reduced Risk of Syphilis Reinfection in Men Interviewed by Disease Intervention Specialists: A Pilot Study

Introduction

Syphilis is a highly transmissible sexually transmitted infection. Rising rates of infection and reinfection are of great concern to public health officials. In local health departments across the U.S., disease intervention specialists attempt to interview all people diagnosed with early syphilis, to elicit sexual partner information, and to trace and treat the partners. This method of interviewing and contact tracing is an evidence-based practice that reduces the spread of the disease in the community, but few studies address the relationship between the disease intervention specialists' interviews and index patient reinfections. We hypothesized that patients who were interviewed, patients who provided partner information, and patients with more treated partners would have a reduced risk of reinfection.

Methods

Our sample consisted of 82 men listed in the Suffolk County Department of Health Services syphilis log who were diagnosed with primary, secondary, or early latent syphilis. We determined whether and when the patients were reinfected during a set time period, from 2016 to 2020. Kaplan-Meier analyses with log-rank statistics and Cox hazard proportional models were used to calculate time to reinfection and hazard ratios.

Results

Although none of the models produced p<0.05, notable trends were observed. In subset analyses of interviewed patients, 23.8% of patients who named partners were reinfected during the study period, whereas 50% of those who did not name partners were reinfected during that time. In addition, the hazard ratio for index patients who named partners was 0.51 (95% CI=0.225, 1.170, p=0.113). When some or all the patients' partners were treated, 20% were reinfected by the end of the study, whereas 33.3% of cases with no partners treated were reinfected by the end of the study. The hazard ratio for patients with some or all partners treated was 0.48 (95% CI=0.136, 1.711, p=0.258).

Conclusions

Although none of the results was statistically significant, trends suggest that partner elicitation and partner treatment status could be associated with reduced risk of syphilis reinfection. Because this pilot study utilized a small convenience sample that was not tested for statistical power, we could not adequately address these trends. Future studies, with larger sample sizes, should address these relationships.

Syphilis vaccine: challenges, controversies and opportunities

Syphilis is a sexually or vertically (mother to fetus) transmitted disease caused by the infection of Treponema pallidum subspecie pallidum (TPA). The incidence of syphilis has increased over the past years despite the fact that this bacterium is an obligate human pathogen, the infection route is well known, and the disease can be successfully treated with penicillin. As complementary measures to preventive campaigns and early treatment of infected individuals, development of a syphilis vaccine may be crucial for controlling disease spread and/or severity, particularly in countries where the effectiveness of the aforementioned measures is limited. In the last century, several vaccine prototypes have been tested in preclinical studies, mainly in rabbits. While none of them provided protection against infection, some prototypes prevented bacteria from disseminating to distal organs, attenuated lesion development, and accelerated their healing. In spite of these promising results, there is still some controversy regarding the identification of vaccine candidates and the characteristics of a syphilis-protective immune response. In this review, we describe what is known about TPA immune response, and the main mechanisms used by this pathogen to evade it. Moreover, we emphasize the importance of integrating this knowledge, in conjunction with the characterization of outer membrane proteins (OMPs), to expedite the development of a syphilis vaccine that can protect against TPA infection.

Lumbar puncture for neurosyphilis investigation in asymptomatic patients with HIV-syphilis coinfection: a cross-sectional study among infectious disease specialists

BACKGROUND

Syphilis is a major public health issue worldwide. In people living with human immunodeficiency virus (PLHIV), there are higher incidences of both syphilis and neurosyphilis. The criteria for referring PLHIV with syphilis for lumbar puncture is controversial, and the diagnosis of neurosyphilis is challenging.

OBJECTIVE

To describe the knowledge, attitudes, and practices of infectious disease specialists and residents in the context of care for asymptomatic HIV-syphilis coinfection using close-ended questions and case vignettes.

DESIGN AND SETTING

Cross-sectional study conducted in three public health institutions in São Paulo (SP), Brazil.

METHODS

In this cross-sectional study, we invited infectious disease specialists and residents at three academic healthcare institutions to answer a self-completion questionnaire available online or in paper form.

RESULTS

Of 98 participants, only 23.5% provided answers that were in line with the current Brazilian recommendation. Most participants believed that the criteria for lumbar puncture should be extended for people living with HIV with low CD4+ cell counts (52.0%); in addition, participants also believed that late latent syphilis (29.6%) and Venereal Disease Research Laboratory (VDRL) titers ≥ 1:32 (22.4%) should be conditions for lumbar puncture in PLHIV with no neurologic symptoms.

CONCLUSION

This study highlights heterogeneities in the clinical management of HIV-syphilis coinfection. Most infectious disease specialists still consider syphilis stage, VDRL titers and CD4+ cell counts as important parameters when deciding which patients need lumbar puncture for investigating neurosyphilis.

Syphilis Infections, Reinfections and Serological Response in a Large Italian Sexually Transmitted Disease Centre: A Monocentric Retrospective Study

Background: Syphilis infection does not confer definitive and protective immunity against reinfection, and crucial aspects of repeated episodes of syphilis are far from being understood, especially among people living with HIV (PLWH). Methods: In order to explore the burden of syphilis in a large cohort of HIV-negative patients and PLWH, this retrospective study describes the demographics, clinical presentation and treatment outcome of patients with syphilis treated at our clinic from 2013 to 2021. Results: Within the study period, 1859 syphilis episodes (827, 44.5% first infections and 1032, 55.5% reinfections) were recorded. A total of 663 patients, of whom 347 (52%) had PLWH, were considered. Syphilis was mostly diagnosed in males (77%) and European (79%) patients. More than half of syphilis episodes were recorded during the late latent stage (64%) or during follow-up/screening visits for other diseases, while symptomatic stages led to a diagnosis in almost half of HIV-negative patients (p < 0.001). PLWH with syphilis infection were predominantly homo/bisexual (p < 0.001). A significantly higher rate of syphilis reinfection was observed in PLWH, who also demonstrated a higher range of subsequent episodes. The serofast state was found to be similar at the 6- and 12-month follow-up visits. The multivariate analysis carried out in the HIV-positive group showed that an RPR titre >1:16 was an independent predictor for serological non-response. Conclusions: Syphilis reinfections are predominantly diagnosed in HIV-positive MSM. The high rate of asymptomatic presentation among PLWH supports the role of periodical syphilis screening. In PLWH, the only baseline factor associated with an increased risk of non-response was an RPR titre >1:16, while assessment at 12 months after treatment increased the possibility of detecting a serological response, indicating that PLWH have a slower serological response to treatment.

An Updated Review of Recent Advances in Neurosyphilis

Neurosyphilis is caused by Treponema pallidum invading the central nervous system, of which the incidence is increasing worldwide. Due to its variable clinical manifestations, diagnosis of neurosyphilis remains challenging, especially the asymptomatic form. This review focuses on recent advances in neurosyphilis, including epidemiology, clinical manifestations, laboratory findings, comorbidities, diagnosis, treatment, prognosis, and basic research. The expansion of men who have sex with men and the infection of human immunodeficiency virus mainly accounted for the increasing incidence of neurosyphilis. The rate of some historically described forms of neurosyphilis in the pre-antibiotic era declined significantly; atypical features are more prevalent. Neurosyphilis, regarded as a great mimicker for neuro-ophthalmic, audio-vestibular, and psychiatric disorders, often presents concomitantly with other diseases, including metabolic disorders. Studies on long non-coding RNAs, miRNAs, chemokines, and metabolites in peripheral blood and cerebrospinal fluid may facilitate exploring the pathogenesis and identifying novel biomarkers of neurosyphilis. The drug resistance of Treponema pallidum to penicillin has not been reported; ceftriaxone was proposed to be more effective than penicillin, whereas few randomized controlled trials supported this view. This study may pave the way for further research, especially the diagnosis and treatment of neurosyphilis.

Point-of-Care Diagnostics for Diagnosis of Active Syphilis Infection: Needs, Challenges and the Way Forward

Syphilis, a curable sexually transmitted infection, has re-emerged as a global public health threat with an estimated 5.6 million new cases every year. Pregnant women and men who have sex with men are key target populations for syphilis control and prevention programs. Frequent syphilis testing for timely and accurate diagnosis of active infections for appropriate clinical management is a key strategy to effectively prevent disease transmission. However, there are persistent challenges in the diagnostic landscape and service delivery/testing models that hinder global syphilis control efforts. In this commentary, we summarise the current trends and challenges in diagnosis of active syphilis infection and identify the data gaps and key areas for research and development of novel point-of-care diagnostics which could help to overcome the present technological, individual and structural barriers in access to syphilis testing. We present expert opinion on future research which will be required to accelerate the validation and implementation of new point-of-care diagnostics in real-world settings.

Tina's ParTy line: Polysubstance use patterns in sexual minority men living with HIV who use methamphetamine

INTRODUCTION

This cross-sectional study examined the associations of demographic, structural and psychological factors with distinct typologies of polysubstance use in sexual minority men (SMM) living with HIV who use methamphetamine.

METHODS

In total, 161 SMM living with HIV who reported methamphetamine use in the past 3 months were recruited in San Francisco from 2013 to 2017 for a randomised controlled trial. A latent class analysis was conducted by leveraging baseline measures of self-reported use of 15 substances in the past 3 months as well as validated screening measures of hazardous alcohol and cannabis use. Correlates of latent class membership were examined using a three-step categorical latent variable logistic regression.

RESULTS

Four typologies of substance use were identified: (i) methamphetamine use only (43%); (ii) methamphetamine and crack-cocaine use (22%); (iii) party and play use-methamphetamine, gamma-hydroxybutyrate and amyl nitrites (i.e. poppers) with erectile dysfunction drugs (31%); and (iv) high polysubstance use (4%). SMM of colour and those with a history of incarceration were more commonly classified as engaging in methamphetamine and crack-cocaine use compared to party and play use. Men with higher sexual compulsivity scores were more commonly classified as engaging in party and play use and polysubstance use.

DISCUSSION AND CONCLUSIONS

There is substantial heterogeneity in polysubstance use patterns among SMM living with HIV who use methamphetamine. This will inform the development of tailored substance use interventions addressing the unique needs of SMM of colour and targeting sexual compulsivity as a prominent comorbidity for some men.

Social and Behavioral Correlates of Sexually Transmitted Infections among Men who Have Sex with Men who Use Alcohol in the San Francisco Bay Area

The risk of acquiring sexually transmitted infections (STIs) among men who have sex with men (MSM) is driven by various socio-behavioral factors. From 2015-2017, 247 MSM ≥ 18 years-old who reported alcohol use in the past year, were recruited into a cross-sectional study in San Francisco. Participants completed a survey assessing socio-demographics, substance use and treatment, sexual behaviors, HIV status and self-reported STI diagnosis in the past 6 months. Multivariable logistic regression models stratified by HIV status were used to identify the correlates of STIs. Of 247 MSM, the prevalence of bacterial STIs were: gonorrhea (12.9%), chlamydia (9.3%) and syphilis (6.0%). Among 177 MSM living without HIV, factors significantly associated with recent STI diagnosis were: current pre-exposure prophylaxis (PrEP) use (aOR = 3.53, 95% CI: 1.42-8.75, p ≤ .01), popper use during sex in the past 6 months (aOR = 3.16, 95% CI = 1.34-7.47, p ≤ .01) and a history of alcohol treatment (aOR = 0.17, 95% CI = 0.04-0.68, p = .01). Also, in a sensitivity analysis (removing PrEP), any receptive condomless anal sex was independently associated with recent STI diagnosis (aOR = 2.86, 95% CI = 1.15-7.08, p = .02). Among 70 MSM living with HIV, factors significantly associated with recent STI diagnosis were: White race/ethnicity (adjusted odds ratio [aOR] = 7.36, 95% confidence interval [CI] = 1.48-36.62, p = .01), younger age (aOR = 0.90, 95% CI: 0.84-0.97, p < .01) and a higher number of male sexual partners in the past 6 months (aOR = 1.03, 95% CI = 1.00-1.06, p = .02). Sexual health interventions that address the unique needs of MSM living with and without HIV who use alcohol in San Francisco are needed to reduce STI acquisition and transmission.

Previous Syphilis Alters the Course of Subsequent Episodes of Syphilis

BACKGROUND

The influence of previous syphilis on the course of a subsequent episode is unknown.

METHODS

Individuals enrolled in a study of cerebrospinal fluid (CSF) abnormalities in syphilis were allowed to enroll in the study again with subsequent syphilis. For each participant, the index episode was defined as the most recent syphilis episode for which the study entry visit was performed within 30 days of the syphilis diagnosis date. Venipuncture and lumbar puncture (LP) were performed. Total number of syphilis episodes was determined by review of medical and public health records. T. pallidum DNA in blood and rRNA in CSF were detected by polymerase chain reaction (PCR) and reverse transcriptase PCR. Odds ratios (ORs) with 95% confidence intervals (95% CI) were determined by logistic regression.

RESULTS

651 individuals had one (n = 482), two (n = 121) or three or more (n = 48) episodes of syphilis. The proportion of individuals whose index episode was early latent stage was significantly higher in those with ≥3 syphilis episodes; this relationship was reduced to a trend when rate of testing was taken into account. Adjusted odds (aOR) of detection of T. pallidum DNA in blood or rRNA in CSF at the index episode were significantly lower in those with previous syphilis (0.17 [95% CI, 0.09-0.31] and 0.15 [95% CI, 0.07-0.35]). The aOR for neurosyphilis at the index episode was also significantly lower in individuals with previous syphilis (0.54 [95% CI, 0.34-0.87]).

CONCLUSIONS

Previous syphilis attenuates the manifestations of subsequent infection with T. pallidum.

Clinical outcomes of syphilis in HIV-negative and HIV-positive MSM: occurrence of repeat syphilis episodes and non-treponemal serology responses

OBJECTIVES

HIV-positive men who have sex with men (MSM) may be at a higher risk of repeat syphilis, have different clinical manifestations and have a different serological response to treatment compared with HIV-negative MSM. The objective of this study was to assess whether HIV-negative and HIV-positive MSM with infectious syphilis (primary, secondary or early latent) differed in history of previous syphilis episodes, disease stage and non-treponemal titre of initial and repeat episodes, and the titre response 6 and 12 months after treatment. Furthermore, determinants associated with an inadequate titre response after treatment were explored.

METHODS

This retrospective analysis used data of five longitudinal studies (four cohorts; one randomised controlled trial) conducted at the STI clinic in Amsterdam, the Netherlands. Participants were tested for syphilis and completed questionnaires on sexual risk behaviour every 3-6 months. We included data of participants with ≥1 syphilis diagnosis in 2014-2019. Pearson's χ² test was used to compare HIV-negative and HIV-positive MSM in occurrence of previous syphilis episodes, disease stage of initial and repeat syphilis episode and non-treponemal titre treatment responses.

RESULTS

We included 355 participants with total 459 syphilis episodes. HIV-positive MSM were more likely to have a history of previous syphilis episodes compared with HIV-negative MSM (68/90 (75.6%) vs 96/265 (36.2%); p<0.001). Moreover, HIV-positive MSM with repeat syphilis were less often diagnosed with primary syphilis (7/73 (9.6%) vs 36/126 (28.6%)) and more often diagnosed with secondary syphilis (16/73 (21.9%) vs 17/126 (13.5%)) and early latent syphilis (50/73 (68.5%) vs 73/126 (57.9%)) (p=0.005). While not significantly different at 12 months, HIV-negative MSM were more likely to have an adequate titre response after 6 months compared with HIV-positive MSM (138/143 (96.5%) vs 66/74 (89.2%); p=0.032).

CONCLUSIONS

In repeat syphilis, HIV infection is associated with advanced syphilis stages and with higher non-treponemal titres. HIV infection affects the serological outcome after treatment, as an adequate titre response was observed earlier in HIV-negative MSM.

An Investigation of Early Syphilis Among Men Who have Sex with Men: Alaska, 2018: Findings from a 2018 Rapid Ethnographic Assessment

The state of Alaska had a sharp increase in cases of primary and secondary syphilis among gay, bisexual, and other men who have sex with men (GBMSM) in 2018, centered in Anchorage. A rapid ethnographic assessment was conducted in October 2018 to examine contextual factors contributing to local increases in syphilis. The assessment team conducted qualitative interviews with 64 (N=49 interviews) key informants in Anchorage and Matanuska-Susitna Valley identified through the STD/HIV program at the Alaska Department of Health and Social Services, Division of Public Health (ADPH):  ADPH staff (n = 11; 22%) Medical Providers (n = 18; 37%), Community-Based Organizations/Partners (n = 9; 18%), and GBMSM Community Members (n = 11; 22%). This project was deemed exempt from IRB review. Primary factors affecting syphilis transmission, care, and treatment among GBMSM were: (1) Low awareness about the current syphilis outbreak and ambivalence about syphilis and other STIs; (2) Aspects of sexual partnering such as travel, tourism, and the use of online sites and apps to facilitate anonymous sex and multiple (both sequential/concurrent) partnering; (3) The synergistic effects of substance use, homelessness, and transactional sex; (4) Choosing condomless sex; and (5) Challenges accessing healthcare, including the ability to find appropriate and culturally competent care. Syphilis increases may have been influenced by factors which spanned multiple sectors of the Anchorage community, including individual behavior, community-level risk and protective factors, and use of and interactions with resources offered by ADPH, community-based organizations, and medical providers.

Previous Syphilis Alters the Course of Subsequent Episodes of Syphilis

BACKGROUND

Individuals with previous syphilis may be more likely to be asymptomatic when they are reinfected with Treponema pallidum.

METHODS

Individuals enrolled in a study of cerebrospinal fluid (CSF) abnormalities in syphilis were allowed to enroll in the study again with subsequent syphilis. For each participant, the index episode was defined as the most recent syphilis episode for which the study entry visit was performed within 30 days of the syphilis diagnosis date. Venipuncture and lumbar puncture were performed. The total number of syphilis episodes was determined by review of medical and public health records. Treponema pallidum DNA in blood and rRNA in CSF were detected using polymerase chain reaction (PCR) and reverse transcriptase PCR. Odds ratios (ORs) with 95% confidence intervals (CIs) were determined using logistic regression.

RESULTS

701 individuals had 1 (n = 478), 2 (n = 155), or ≥3 (n = 68) episodes of syphilis. The proportion of individuals whose index episode was asymptomatic significantly increased with increased number of syphilis episodes (P < .001). This difference was not explained by frequency of serological tests. Adjusted ORs (aORs) of detection of T. pallidum DNA in blood or rRNA in CSF at the index episode were significantly lower in those with previous syphilis (0.13; 95% CI, .08-.23, and 0.06, 95% CI, .02-.17). The aOR of neurosyphilis at the index episode was also significantly lower in individuals with previous syphilis (0.43; 95% CI, .27-.68).

CONCLUSIONS

Previous syphilis attenuates clinical and laboratory manifestations of infection with T. pallidum.

Characteristics of Gay, Bisexual and Other Men Who Have Sex With Men With Multiple Diagnoses of Infectious Syphilis in British Columbia, Canada, 2005-2014

BACKGROUND

Infectious syphilis has increased substantially over the past decade. Targeting limited public health resources toward subpopulations with multiple reinfections may have a large impact in reducing onward transmission within a community.

METHODS

A chart review was conducted for individuals with 4 or more infectious syphilis diagnoses between 2005 and 2014 (the top 1% of all syphilis diagnoses in British Columbia, Canada). We characterized the sociodemographics, partner notification outcomes and social network.

RESULTS

Between 2005 and 2014, there were 30 individuals with 4 or more syphilis diagnoses, accounting for 139 diagnoses. All were men who have sex with men and 29 (96%) were human immunodeficiency virus-positive. Of the 139 diagnoses, 65% occurred in the early latent stage of infection, 22% in the secondary stage, and 14% in the primary stage. The median number of sexual partners per diagnosis was 5 (range, 1-50). Among the 838 partners reported, 79% were notifiable, 53% were notified, and 23% were reported to be tested or treated. Sexual network mapping showed that almost half of the members of this group could be linked to one another either directly or indirectly via partners over 10 years. Social network mapping demonstrated high connectivity, with 4 venues associated with almost two thirds of the study population.

CONCLUSIONS

The connectivity and recurrent diagnoses in this study population suggest potential benefits of targeted interventions to individuals with multiple diagnoses and their partners. Our study highlights the need for enhanced care, increased syphilis testing frequency, and exploring alternative preventative methods among individuals with syphilis rediagnoses to reduce syphilis incidence.

Evaluation of 4 Algorithms to Identify Incident Syphilis Among HIV-Positive Men Who Have Sex With Men Engaged in Primary Care

We developed 4 algorithms for syphilis among HIV-positive men who have sex with men who engaged in primary care in 2016 to 2017. Clinician-based diagnosis from chart reviews was the gold standard. Sensitivities ranged from 74.2% to 93.9%. Specificities were greater than 99% with positive and negative predictive values of greater than 95%. Algorithms that incorporated treatment data performed best.

Comparative genomics and full-length Tprk profiling of Treponema pallidum subsp. pallidum reinfection

Developing a vaccine against Treponema pallidum subspecies pallidum, the causative agent of syphilis, remains a public health priority. Syphilis vaccine design efforts have been complicated by lack of an in vitro T. pallidum culture system, prolific antigenic variation in outer membrane protein TprK, and lack of functional annotation for nearly half of the genes. Understanding the genetic basis of T. pallidum reinfection can provide insights into variation among strains that escape cross-protective immunity. Here, we present comparative genomic sequencing and deep, full-length tprK profiling of two T. pallidum isolates from blood from the same patient that were collected six years apart. Notably, this patient was diagnosed with syphilis four times, with two of these episodes meeting the definition of neurosyphilis, during this interval. Outside of the highly variable tprK gene, we identified 14 coding changes in 13 genes. Nine of these genes putatively localized to the periplasmic or outer membrane spaces, consistent with a potential role in serological immunoevasion. Using a newly developed full-length tprK deep sequencing protocol, we profiled the diversity of this gene that far outpaces the rest of the genome. Intriguingly, we found that the reinfecting isolate demonstrated less diversity across each tprK variable region compared to the isolate from the first infection. Notably, the two isolates did not share any full-length TprK sequences. Our results are consistent with an immunodominant-evasion model in which the diversity of TprK explains the ability of T. pallidum to successfully reinfect individuals, even when they have been infected with the organism multiple times.

An Application of Syndemic Theory to Identify Drivers of the Syphilis Epidemic Among Gay, Bisexual, and Other Men Who Have Sex With Men

BACKGROUND

We applied syndemic theory to explore the degree to which syndemic conditions explain the syphilis epidemic affecting Canadian gay and bisexual men who have sex with men (GBMSM).

METHODS

Data from a national survey comprising 7872 GBMSM were analyzed using multivariable logistic regression to measure associations between recent syphilis diagnosis (RSD; in previous 12 months) and the following variables: (1) sociodemographic information (sexuality, HIV status, age, income, ethnicity, relationship status), (2) antigay stigma (bullying, physical violence, sexual violence, career discrimination, health care discrimination), (3) syndemic conditions (suicidality, intimate partner violence, depression, illicit substance use, binge drinking), (4) sexual behaviors, (5) health care discrimination, and (6) the cumulative count of antigay experiences and syndemic conditions.

RESULTS

Three percent (n = 235) of GBMSM surveyed reported an RSD. Men were more likely to report an RSD if they were HIV positive (adjusted odds ratio [AOR], 6.27; 95% confidence interval [CI], 4.66-8.43). Recent syphilis diagnosis was also positively associated with career discrimination, health care discrimination, substance use, and intimate partner violence. Furthermore, prevalence of RSD increased with each additional form of stigma or syndemic condition. The odds of reporting RSD was 5.2 (95% CI, 1.0-25.9) times higher for men who reported experiencing all 4 forms of antigay stigma compared with those who reported no stigma, after adjusting for sociodemographics. Similarly, the adjusted odds of reporting RSD was 12.2 (95% CI, 2.0%-74.8%) times higher for GBMSM experiencing 5 syndemic conditions compared with those reporting no syndemic conditions.

CONCLUSIONS

Evidence from this large cross-sectional study suggests that the Canadian syphilis epidemic among GBMSM is being driven by a syndemic constituted by multiple social and psychological conditions. Interventions addressing specific psychosocial health outcomes that increase the risk for syphilis should be developed and integrated within targeted sexual health services and syphilis prevention initiatives.

Factors associated with syphilis treatment failure and reinfection: a longitudinal cohort study in Shenzhen, China

Background

The treatment failure and reinfection rates among syphilis patients are high, and relevant studies in China are limited. The aim of this study was to detect the rates of treatment failure and reinfection after syphilis treatment and to explore the potential associated factors.

Methods

We conducted a longitudinal cohort study in a sexually transmitted disease clinic, the Department of Dermatology and Venereology in Nanshan Center for Chronic Disease Control. Serological testing was performed at baseline and throughout the 2-year follow-up for syphilis patients. To identify potential predictors of treatment outcomes, multivariate logistics analyses were utilized to compare the demographic and clinical characteristics of patients with serological failure/reinfection to those with serological cure/serofast.

Results

From June 2011 to June 2016, a total of 1133 patients were screened for syphilis. Among the 770 patients who completed the 2-year follow-up, 510 first-diagnosed patients were included in the final analysis. Multivariate logistics analysis revealed the stage of syphilis (secondary syphilis VS. primary syphilis: adjusted odds ratio, 3.50; 95% confidence interval, 1.11-15.47; p = 0.04), HIV status (positive VS. negative: adjusted odds ratio, 3.06; 95% confidence interval, 1.15-8.04; p = 0.02) and frequency of condom use (always use VS. never use: adjusted odds ratio, 0.28; 95% confidence interval 0.08-0.75; p = 0.02) were significantly associated with the serological outcome.

Conclusions

The clinical implications of our findings suggest that it is very important to perform regular clinical and serologic evaluations after treatment. Health counseling and safety education on sex activity should be intensified among HIV-infected patients and secondary syphilis patients after treatment.