Sexual network characteristics of men who have sex with men with syphilis and/or gonorrhoea/chlamydia in Lima, Peru: network patterns as roadmaps for STI prevention interventions

Understanding dynamics and overlapping epidemiologies of HIV, HSV-2, chlamydia, gonorrhea, and syphilis in sexual networks of men who have sex with men

Introduction

We aimed to investigate the overlapping epidemiologies of human immunodeficiency virus (HIV), herpes simplex virus type 2 (HSV-2), chlamydia, gonorrhea, and syphilis in sexual networks of men who have sex with men (MSM), and to explore to what extent the epidemiology of one sexually transmitted infection (STI) relates to or differs from that of another STI.

Methods

An individual-based Monte Carlo simulation model was employed to simulate the concurrent transmission of STIs within diverse sexual networks of MSM. The model simulated sexual partnering, birth, death, and STI transmission within each specific sexual network. The model parameters were chosen based on the current knowledge and understanding of the natural history, transmission, and epidemiology of each considered STI. Associations were measured using the Spearman's rank correlation coefficient (SRCC) and maximal information coefficient (MIC).

Results

A total of 500 sexual networks were simulated by varying the mean and variance of the number of partners for both short-term and all partnerships, degree correlation, and clustering coefficient. HSV-2 had the highest current infection prevalence across the simulations, followed by HIV, chlamydia, syphilis, and gonorrhea. Threshold and saturation effects emerged in the relationship between STIs across the simulated networks, and all STIs demonstrated moderate to strong associations. The strongest current infection prevalence association was between HIV and gonorrhea, with an SRCC of 0.84 (95% CI: 0.80-0.87) and an MIC of 0.81 (95% CI: 0.74-0.88). The weakest association was between HSV-2 and syphilis, with an SRCC of 0.54 (95% CI: 0.48-0.59) and an MIC of 0.57 (95% CI, 0.49-0.65). Gonorrhea exhibited the strongest associations with the other STIs while syphilis had the weakest associations. Across the simulated networks, proportions of the population with zero, one, two, three, four, and five concurrent STI infections were 48.6, 37.7, 11.1, 2.4, 0.3, and < 0.1%, respectively. For lifetime exposure to these infections, these proportions were 13.6, 21.0, 22.9, 24.3, 13.4, and 4.8%, respectively.

Conclusion

STI epidemiologies demonstrate substantial overlap and associations, alongside nuanced differences that shape a unique pattern for each STI. Gonorrhea exhibits an "intermediate STI epidemiology," reflected by the highest average correlation coefficient with other STIs.

Sexual network characteristics and partnership types among men who have sex with men diagnosed with syphilis, gonorrhoea and/or chlamydia in Lima, Peru

OBJECTIVES

Sexual networks are known to structure sexually transmitted infection (STI) transmission among men who have sex with men (MSM). We sought to estimate the risks of STI diagnosis for various partnership types within these networks.

METHODS

Our cross-sectional survey analysed data from 1376 MSM screened for a partner management intervention in Lima, Peru. Participants were tested for HIV, syphilis, gonorrhoea (NG) and chlamydia (CT) and completed surveys on their demographics, sexual identity/role, HIV status, partnership types and sexual network from the prior 90 days. χ2 and Wilcoxon rank-sum tests compared participants without an STI to those diagnosed with (1) syphilis, (2) NG and/or CT (NG/CT) and (3) syphilis and NG/CT coinfection (coinfection).

RESULTS

40.8% (n=561/1376) of participants were diagnosed with an STI (syphilis: 14.9%, NG/CT: 16.4%, coinfection: 9.5%). 47.9% of all participants were living with HIV and 8.9% were newly diagnosed. A greater proportion of participants with syphilis and coinfection were living with HIV (73.5%, p<0.001; 71.0%, p<0.001) compared with those with NG/CT (47.8%) or no STI (37.8%). Participants with syphilis more often reported sex-on-premises venues (SOPVs) as the location of their last sexual encounter (51.7%, p=0.038) while those with NG/CT tended to meet their last sexual partner online (72.8%, p=0.031). Respondents with coinfection were the only STI group more likely to report transactional sex than participants without an STI (31.3%, p=0.039).

CONCLUSIONS

Sexual networks and partnership types of Peruvian MSM are associated with differential risks for STIs. Participants diagnosed with syphilis tended to meet single-encounter casual partners at SOPV, while MSM with NG/CT were younger and often contacted casual partners online. Coinfection had higher frequency of transactional sex. These findings suggest the potential importance of public health interventions through combined syphilis/HIV screening at SOPV, syphilis screening at routine clinic appointments for MSM living with HIV and directed advertisements and/or access to NG/CT testing through online platforms.

Syphilis prevalence and correlates of infection among Venezuelan refugees and migrants in Colombia: findings of a cross-sectional biobehavioral survey

Background

Population-based estimates of syphilis prevalence are critical to informing public health response. We aimed to measure syphilis prevalence among Venezuelan refugees and migrants in Colombia to inform public health programming.

Methods

Between July 2021 and February 2022, we surveyed 6221 adult Venezuelan refugees and migrants in four cities in Colombia using respondent-driven sampling (RDS). Participants completed a survey and dual-rapid HIV/treponemal syphilis screening. Confirmatory laboratory-based rapid plasma reagin testing was conducted on whole blood samples. Active syphilis infection was defined as RPR titer ≥ 1:8 and no self-reported syphilis treatment. We used multivariable regression models to identify associations with active syphilis infection among subgroups by gender and history of pregnancy (cisgender men n = 2123, cisgender women n = 4044, transgender/nonbinary people n = 47, pregnant women n = 150).

Findings

Population (RDS-weighted) prevalence of laboratory-confirmed syphilis was 5.1% (95% CI: 4.6-5.6). Syphilis prevalence was 5.8% (weighted) among men; lifetime sexually transmitted infections (STI) diagnosis, same-sex relationships, HIV infection, and partner number were independently associated with syphilis infection. Syphilis prevalence was 4.6% (weighted) in women; correlates of infection included: lifetime STI diagnosis, food insecurity, current engagement in sex work, current pregnancy, any unsafe night in Colombia, irregular migration status, and no healthcare utilization in Colombia. 14.9% (unweighted) of transgender participants had syphilis infection; correlates of infection included partner number and HIV infection. The prevalence of syphilis was 9.0% (weighted) among pregnant women, which was associated with lifetime STI diagnosis.

Interpretation

Syphilis among Venezuelans in Colombia is high. Correlates of infection are distinct among demographic groups, spanning sexual and social vulnerabilities, suggesting tailored public health strategies.

Funding

US President's Emergency Plan for AIDS Relief through the U.S. Centers for Disease Control and Prevention.

Incidence, risk factors, and clinical findings of syphilis among men living with HIV in Croatia during the COVID-19 pandemic

We conducted a nationwide longitudinal observational study to estimate the incidence of syphilis in a cohort of male persons living with HIV (MLWH) in Croatia in the pre-COVID-19 and COVID-19 years. Data were reviewed and extracted from the clinical database. We analyzed 1187 MLWH (≥ 18 years) in care in Croatia from 2018 to 2021 and used Poisson regression to calculate rates. We observed a 91.4% increase in incidence between 2019 and 2020; the overall rate was 6.0/100 person-years, and the annual rate ranged from 3.3/100 person-years in 2018 to 9.3/100 person-years in 2021. We found higher rates in men who have sex with men, MLWH with a baseline history of syphilis, MLWH with a more recent HIV diagnosis, and a lower rate in those who had clinical AIDS. The rate of syphilis serological testing was 3.5% lower in 2020 compared to 2019. Recurrent syphilis was more likely asymptomatic compared to the first episodes. In conclusion, during the COVID-19 epidemic years, there was a huge increase in syphilis. Results highlight the need for enhanced and novel prevention interventions.

High Incidence, Reinfections, and Active Syphilis in Populations Attending a Specialized HIV Clinic in Mexico, a Dynamic Cohort Study

Syphilis, a sexually transmitted infection, has reemerged in many vulnerable groups around the world. The objective of the current study was to determine the prevalence and incidence of syphilis among people who attended a specialized HIV clinic in Mexico from 2011 to 2015. Databases from the laboratory were analyzed, and the following four groups were formed: people seeking HIV-1 voluntary counseling and testing (VCT), people in prison (PPr), people living with HIV (PLWH), and patients from primary care clinics (others). The diagnosis of syphilis was made using the reverse algorithm; antibody titers were examined to determine the stage of infection. Baseline data were analyzed and, with follow-up information, a retrospective dynamic cohort was formed. Factors associated with the seroprevalence of syphilis and active syphilis were evaluated by the chi-square test. Moreover, risk factors for the incidence of syphilis were described. A total of 81,863 baseline individuals were analyzed. The seroprevalence of syphilis was 9.9% in the VCT group, 8.2% in the PPr group, 37.0% in the PLWH group, and 8.7% in the others group; the prevalence of active syphilis was 1.7-13.1%. A total of 11,124 people were followed up. The incidence (cases per 100 person-years) was 3.5 among the VCT group, 16.0 among the PLWH group, and < 0.1 among both the PPr and others groups, respectively; moreover, the frequency of reinfections was 11.1-24.4%. The high prevalence and incidence of syphilis, active syphilis, and reinfections among men, transgender people, individuals aged 20-39 years, and people with a history of HIV or hepatitis B suggest that it is critical to improve prevention, diagnosis, and treatment measures to stop the reemergence of syphilis. There are also new factors such as methamphetamine use, group sex, or contacting partners over the internet that are associated with syphilis. In addition, HIV preexposure prophylaxis could contribute to the increased incidence of syphilis by providing false security in the prevention of STIs, thereby increasing risky sexual behaviors.

Sexual health norms and communication patterns within the close social networks of men who have sex with men and transgender women in Lima, Peru: a 2017 cross-sectional study

BACKGROUND

Social networks, norms, and discussions about sexual health may inform sexual practices, influencing risk of human immunodeficiency virus (HIV) or sexually transmitted infection (STI) acquisition. To better understand social networks of Peruvian men who have sex with men (MSM) and transgender women (trans women), we examined key social network members (SNMs), participant perceptions of these network members' opinions toward sexual health behaviors, and associations between network member characteristics and condomless anal intercourse (CAI).

METHODS

In a 2017 cross-sectional study, a convenience sample of 565 MSM and trans women with HIV-negative or unknown serostatus was asked to identify three close SNMs; describe discussions about HIV and STI prevention with each; and report perceived opinions of condom use, HIV/STI testing, and partner notification of STIs. Generalized estimating equations evaluated relationships between SNM characteristics, opinions, and discussions and participant-reported CAI.

RESULTS

Among participants who identified as MSM, 42.3% of key SNMs were perceived to identify as gay. MSM "never" discussed HIV and STI prevention concerns with 42.4% of heterosexual SNMs, but discussed them "at least once weekly" with 16.9 and 16.6% of gay- and bisexual- identifying SNMs, respectively. Among participants who identified as trans women, 28.2% of key SNMs were perceived as heterosexual; 25.9%, as bisexual; 24.7%, as transgender; and 21.2%, as gay. Trans women discussed HIV/STI prevention least with cis-gender heterosexual network members (40.2% "never") and most with transgender network members (27.1% "at least once weekly"). Participants perceived most of their close social network to be completely in favor of condom use (71.2% MSM SNMs, 61.5% trans women SNMs) and HIV/STI testing (73.1% MSM SNMs, 75.6% trans women SNMs), but described less support for partner STI notification (33.4% MSM SNMs, 37.4% trans women SNMs). Most participants reported CAI with at least one of their past three sexual partners (77.5% MSM, 62.8% trans women). SNM characteristics were not significantly associated with participant-reported frequency of CAI.

CONCLUSIONS

Findings compare social support, perceived social norms, and discussion patterns of Peruvian MSM and trans women, offering insight into social contexts and sexual behaviors.

TRIAL REGISTRATION

The parent study from which this analysis was derived was registered at ClinicalTrials.gov (Identifier: NCT03010020 ) on January 4, 2017.