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Background Hepatitis C virus (HCV) reinfection rates are substantially higher than primary infection rates among men who have sex with men (MSM) with human immunodeficiency virus (HIV) in European cohorts. The behaviors mediating this high rate of transmission among MSM are poorly characterized. Methods We performed a prospective cohort study in New York City (NYC) of MSM with HIV who cleared HCV to determine the incidence of and risk factors for HCV reinfection. We assessed the risk behaviors for primary HCV in NYC: receipt of semen in the rectum, and sexualized methamphetamine use, along with route of use. Multivariable analysis was performed with Andersen-Gill extension of the Cox proportional hazards model. Results From 2000 through 2018, among 304 MSM with HIV who cleared HCV, 42 reinfections occurred over 898 person-years, for an incidence rate of 4.7 per 100 person-years. Assessing 1245 postclearance visits, only receipt of semen into the rectum was associated with reinfection (hazard ratio, 9.7 [95% confidence interval: 3.3–28.3], P <.001); methamphetamine use was not. Conclusions The high HCV reinfection rate over almost 2 decades demonstrates that sexual transmission of HCV is not inefficient or unusual and that direct-acting antiviral treatment is not sufficient for HCV elimination among MSM in NYC. The contrasts between both the rates of and risk factors for primary and HCV reinfection suggest that HCV prevalence is highly heterogenous among sexual networks and that sexualized methamphetamine use, rather than mediating transmission, is instead a surrogate marker for the highest HCV prevalence networks. As neither condoms nor treatment have been successful strategies for HCV prevention in NYC, novel interventions are needed to stem this sexually transmitted HCV epidemic. [ABSTRACT FROM AUTHOR]

Background. The patterns of sexually transmitted infections (STIs) in populations may be influenced by the sexual mixing within the population. We aimed to investigate the assortative sexual mixing pattern by bisexuality in male-male partnerships. Methods. This was a retrospective repeated crosssectional study of men with mostly regular male partners attending the Melbourne Sexual Health Centre between 2011 and 2019. Data on sexual practices, including their sexual practices, presence of other male/female sex partners and the gender of sexual partners in the previous 3 and 12 months, were collected using computer-assisted self-interview. We calculated the proportion of male partnerships where at least one man in the partnership reported a female sex partner. Results. A total of 2056 male-male partnerships (i.e. 4112 individuals) with a median age of 29 years (IQR 25 to 35) were included. Overall, in 94.4% (1941/2056) of male-male partnerships both men had male partners only; however, in 5.5% (113/2056) of partnerships, one man had both male and female partners, and in 0.1% (2/2056) partnerships, both men had both male and female partners. No assortative relationship was found on the sexual mixing by bisexuality in male-male partnerships due to the low assortativity coefficient (r = 0.006, 95% CI: -0.004 to 0.016). Conclusion. One in 20male-male partnerships had at least one man who had both male and female partners within the preceding year. Individuals were not selective by bisexuality, suggesting that partnerships of bisexual individuals are mixed proportionately to the distribution of their characteristics. Still, these sexual mixing practices may affect STI transmission dynamics. [ABSTRACT FROM AUTHOR]

Summary: Background: Despite high rates of HIV transmission among men who have sex with men (MSM) in Lima, Peru, limited data exist on the sexual network characteristics or risk factors for secondary HIV transmission among MSM with uncontrolled HIV infection. We report the frequency of serodiscordant, condomless anal intercourse (CAI) and associated sexual network characteristics among MSM in Lima with detectable HIV viremia and compare to those with undetectable viremia. Methods: This cross-sectional analysis includes MSM who tested positive for HIV-1 during screening for a trial of partner management and STI control (June 2022–January 2023). Participants were tested for HIV, gonorrhoea, chlamydia, and syphilis, and completed questionnaires on their demographic characteristics, sexual identity and behaviour, sexual network structures and engagement in HIV care. Findings: Of 665 MSM, 153 (23%) had detectable (>200 copies/mL) viremia. 75% (499/662) of men living with HIV were previously diagnosed, with 94% (n = 469/499) reporting that they were on ART, and 93% (n = 436/469) virally suppressed. 96% (n = 147/153) of men with detectable viremia reported serodiscordant CAI with at least one of their last three sexual partners, and 74% (n = 106/144) reported the same with all three of their recent partners. In contrast, 62% (n = 302/489) of men with undetectable viral load reported serodiscordant CAI with all of their last three partners (p

The configuration of one's sexual network has been shown to influence sexually transmitted infection (STI) acquisition in some populations. Young Black men who have sex with women (MSW) have high rates of STIs, yet little is known about their sexual networks. The purpose of this study is to describe the characteristics of sexual networks and their association with selected STI infections among young Black MSW. Black MSW aged 15–26 years who were enrolled in the New Orleans community-based screening program named Check It from March 2018 to March 2020 were tested for C. trachomatis and N. gonorrhoeae infection and asked about the nature of their sexual partnerships. Sexual partnerships with women were defined as dyadic, somewhat dense (either themselves or their partner had multiple partners), and dense (both they and their partner(s) had multiple partners). Men (n = 1,350) reported 2,291 sex partners. The percentage of men who reported their networks were dyadic, somewhat dense, and dense was 48.7%, 27.7%, and 23.3%, respectively; 11.2% were STI-positive and 39.2% thought their partner(s) had other partners. Compared to men in dyadic relationships, those in somewhat dense network did not have increased risk of STI infection, but those in dense networks were more likely to have an STI (adjusted odds ratio = 2.06, 95% confidence interval [1.35–3.13]). Young Black MSW, who had multiple partners and who thought their partner(s) had other sex partners were at highest risk for STIs. Providers should probe not only about the youth's personal risk but should probe about perceived sexual partners' risk for more targeted counseling/STI testing. [ABSTRACT FROM AUTHOR]

Rates of reported gonorrhea and chlamydial infections have increased substantially over the past decade in the USA and disparities persist across age and race/ethnicity. We aimed to understand potential changes in sexual behaviors, sexual network attributes, and sexually transmitted infection (STI) screening that may be contributing to these trends. We analyzed data from 29,423 female and 24,605 male respondents ages 15–44 years from the National Survey of Family Growth, 2008–2019. We used survey-weighted linear or logistic regression to evaluate linear temporal trends in sexual behaviors with opposite-sex partners, network attributes, and STI testing, treatment, and diagnosis. Significant declines were observed in condom use at last vaginal sex, mean number of vaginal sex acts, proportion of condom-protected sex acts in the past 4 weeks, and racial/ethnic homophily with current partners among males and females from 2008–2010 through 2017–2019. Among males, mean number of female partners in the past 12 months and concurrency also declined, while the percent reporting ever having sex with another male increased. Past-year testing for chlamydia and any STI increased among females. Research is needed to understand how these changes interact and potentially contribute to increasing reported gonorrhea and chlamydia diagnoses and identify avenues for future intervention. [ABSTRACT FROM AUTHOR]

Background: Population-level estimates of sexual network mixing for parameterizing prediction models of pre-exposure prophylaxis (PrEP) effectiveness are needed to inform prevention of HIV transmission among men who have sex with men (MSM). Estimates obtained by egocentric sampling are vulnerable to information bias due to incomplete respondent knowledge.Methods: We estimated patterns of serosorting and PrEP sorting among MSM in the United States using data from a 2017-2019 egocentric sexual network study. Respondents served as proxies to report the HIV status and PrEP use of recent sexual partners. We contrasted results from a complete-case analysis (unknown HIV and PrEP excluded) versus a bias analysis with respondent-reported data stochastically reclassified to simulate unobserved self-reported data from sexual partners.Results: We found strong evidence of preferential partnering across analytical approaches. The bias analysis showed concordance between sexual partners of HIV diagnosis and PrEP use statuses for MSM with diagnosed HIV (39%; 95% simulation interval: 31, 46), MSM who used PrEP (32%; 21, 37), and MSM who did not use PrEP (83%; 79, 87). The fraction of partners with diagnosed HIV was higher among MSM who used PrEP (11%; 9, 14) compared with MSM who did not use PrEP (4%; 3, 5). Comparatively, across all strata of respondents, the complete-case analysis overestimated the fractions of partners with diagnosed HIV or PrEP use.Conclusions: We found evidence consistent with HIV and PrEP sorting among MSM, which may decrease the population-level effectiveness of PrEP. Bias analyses can improve mixing estimates for parameterization of transmission models. [ABSTRACT FROM AUTHOR]

HIV prevalence is high among transgender women, but little is known about cisgender men who have sex with transgender women (MSTW). The objective of this study was to investigate characteristics and behavior of MSTW compared to transgender women and men who have sex with men (MSM) using a modified respondent-driven sampling design. Seed participants completed a survey and invited up to three sex partners. Forward recruitment continued in waves through the referral of sex partners. Cross-sectional data were assessed using mixed effects models. From February to July 2018, 479 participants in Lima, Peru enrolled (n = 199 transgender women, n = 196 MSTW, and n = 45 MSM). MSTW behavior and identity differed significantly from that of transgender women and MSM. MSTW primarily identified as bisexual (69%) or heterosexual (15%) and only 6% reported male partners. Insertive condomless anal intercourse was reported by 61% of MSTW; 46% did not know their HIV serostatus. Compared to MSTW without male partners, those with recent male partners were more likely to sell sex (OR 15.7, 95% CI 4.1–60.5), and report condomless receptive anal intercourse (OR 89.0, 95% CI 19.1–414.8). This evidence suggests that MSTW are a distinct population from MSM, and highlights the critical need to include MSTW in HIV research and interventions. [ABSTRACT FROM AUTHOR]

In the context of China's gender imbalance, this study addresses the characteristics of sexual networks and their association with condom use in a sample of 713 male migrants (aged 28-64) who have rural hukou (household registration) in China. Descriptive statistics, univariate analyses, and multilevel random intercept models were used to investigate the characteristics of sexual networks and their associations with condom use. We found that age, marital status, type of sex partners, support (the main help given to each sex partner by the participant), type of sexual intercourse, and stability of sexual relationships were associated with condom use. The sexual networks were mainly composed of sex partners of similar age (58.46%), unmarried people (50.53%), and regular partners (49.38%). Married male migrants were more likely to use condoms with casual partners; unmarried male migrants were less likely to use condoms in emotional and stable relationships. Variation in individual factors, sex partners, and sexual relationship characteristics contribute to participation in condomless sex by male migrants. HIV prevention strategies should target unmarried male migrants and their casual sex partners by increasing their awareness of the risk of HIV transmission and the availability of free condoms. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Background: Volatility in sexual contact rates has been recognized as an important factor influencing HIV transmission dynamics. One-time partnerships may be particularly important given the potential to quickly accumulate large number of contacts. Yet, empirical data documenting individual variation in contact rates remain rare. This study provides much needed data on temporal variation in one-time partners to better understand behavioral dynamics and improve the accuracy of transmission models. Methods: Data for this study were obtained from a longitudinal cohort study of young men who have sex with men and transgender women in Chicago. Participants provided sexual network data every 6 months for 2 years. A series of random effects models examined variation in one-time partnership rates and disaggregated within and between associations of exposure variables. Exposure variables included prior number of one-time partners, number of casual partners, and having a main partner. Results: Results indicated substantial between-person and within-person variation in one-time partners. Casual partnerships were positively associated and main partnerships negatively associated with one-time partnership rates. There remained a small positive association between prior one-time partnerships and the current number of one-time partnerships. Conclusions: Despite the preponderance of a low number of one-time partners, substantial variation in one-time partnership rates exists among young men who have sex with men and transgender women. Accordingly, focusing on high contact rate individuals alone may be insufficient to identify periods of highest risk. Future studies should use these estimates to more accurately model how volatility impacts HIV transmission and better understand how this variation influences intervention effectiveness. [ABSTRACT FROM AUTHOR]

Abstract Infectious disease surveillance is often case-based, focused on people diagnosed and their contacts in a predefined time window, and treated as independent across infections. Network analysis of partners and contacts joining multiple investigations and infections can reveal social or temporal trends, providing opportunities for epidemic control within broader networks. We constructed a sociosexual network of all HIV and early syphilis cases and contacts investigated among residents of 11 contiguous counties in North Carolina over a two-year period (2012–2013). We anchored the analysis on new HIV diagnoses (“indexes”), but also included nodes and edges from syphilis investigations that were within the same network component as any new HIV index. After adding syphilis investigations and deduplicating people included in multiple investigations (entity resolution), the final network comprised 1470 people: 569 HIV indexes, 700 contacts to HIV indexes who were not also new cases themselves, and 201 people who were either indexes or contacts in eligible syphilis investigations. Among HIV indexes, nearly half (48%; n = 273) had no located contacts during single-investigation contact tracing, though 25 (9%) of these were identified by other network members and thus not isolated in the final multiple investigation network. Constructing a sociosexual network from cases and contacts across multiple investigations mitigated some effects of unobserved partnerships underlying the HIV epidemic and demonstrated the HIV and syphilis overlap in these networks.

Copyright of AIDS & Behavior is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Affiliation networks are integrated with molecular data to examine HIV transmission. • Core-peripheral structure in venue affiliation is associated with HIV transmission. • Popular social venues potentiate sexual affiliation network of minority young MSM. • Molecular and affiliation network approach informs effective network interventions. • A surveillance-research-community partnership is important to address ethical issues. This study investigates the two-mode core-periphery structures of venue affiliation networks of younger Black men who have sex with men (YBMSM). The study examined the association between these structures and HIV phylogenetic clusters, defined as members who share highly similar HIV strains that are regarded as a proxy for sexual affiliation networks. Using data from 114 YBMSM who are living with HIV in two large U.S. cities, our findings indicate that HIV phylogenetic clustering patterns were found to be associated with social clustering patterns whose members share affiliation with core venues that overlap with those of YBMSM. Distinct HIV transmission patterns were found in each city, a finding that can help to inform tailored venue-based and network intervention strategies. [ABSTRACT FROM AUTHOR]

Background: Individuals who have both opposite- and same-sex partners have the potential to pass sexually transmitted infections (STIs) between high- and low-risk populations. Our aim was to examine assortative sexual mixing in terms of same-sex activity among male-female partnerships.Methods: This was a retrospective repeated cross-sectional study of male-female partnerships attending the Melbourne Sexual Health Centre (MSHC) from 2015 to 2019. Sex of sexual partners was collected via computer-assisted self-interview. We calculated the proportion of partnerships where at least one individual reported same-sex partners in the previous 12months and the degree of assortativity by bisexuality.Results: A total of 2112 male-female partnerships (i.e. 4224 individuals) were included, with a median age of 27 years (IQR 23-31). Overall, 89.3% (1885/2112) of male-female partnerships did not report any other same-sex partners; however, in 9.5% (201/2112) of partnerships, same-sex partners were reported by one individual and in 1.2% (26/2112) of partnerships, both individuals reported same-sex partners. Bisexuality appeared to be slightly assortative in male-female partnerships (r =0.163, 95% CI: 0.150-0.176; P <0.001).Conclusion: One in 10 individuals in male-female partnerships had at least one same-sex partner within the previous 12months. Individuals were minorly selective by bisexuality, suggesting the patterns of bisexual mixing in male-female partners are more variable and this may have a significant impact on STI transmission in heterosexual populations. [ABSTRACT FROM AUTHOR]

Background: The speed with which a pathogen circulates in a sexual network is a function of network connectivity. Cross-sectional connectivity is a function of network features like momentary degree and assortative mixing. Temporal connectivity is driven by partner acquisition rates. The forward-reachable path (FRP) has been proposed as a summary measure of these two aspects of transmission potential. We use empirical data from San Francisco and Atlanta to estimate the generative parameters of the FRP and compare results to the HIV/sexually transmitted infection epidemics in each city.Methods: We used temporal exponential random graph models to estimate the generative parameters for each city's dynamic sexual network from survey data. We then simulated stochastic dynamic networks from the fitted models and calculated the FRP for each realization, overall, and stratified by partnership type and demographics.Results: The overall mean and median paths were higher in San Francisco than in Atlanta. The overall paths for each city were greater than the sum of the paths in each individual partnership network. In the casual partnership network, the mean path was highest in the youngest age group and lowest in the oldest age group, despite the fact that the youngest group had the lowest mean momentary degree and past-year partner counts.Conclusions: The FRP by age group revealed the additional utility of the measure beyond the temporal and cross-sectional network connectivity measures. Other nonnetwork factors are still necessary to infer total epidemic potential for any specific pathogen. [ABSTRACT FROM AUTHOR]

Background: Volatility in sexual contact rates has been recognized as an important factor influencing HIV transmission dynamics. One-time partnerships may be particularly important given the potential to quickly accumulate large number of contacts. Yet, empirical data documenting individual variation in contact rates remain rare. This study provides much needed data on temporal variation in one-time partners to better understand behavioral dynamics and improve the accuracy of transmission models. Methods: Data for this study were obtained from a longitudinal cohort study of young men who have sex with men and transgender women in Chicago. Participants provided sexual network data every 6 months for 2 years. A series of random effects models examined variation in one-time partnership rates and disaggregated within and between associations of exposure variables. Exposure variables included prior number of one-time partners, number of casual partners, and having a main partner. Results: Results indicated substantial between-person and withinperson variation in one-time partners. Casual partnerships were positively associated and main partnerships negatively associated with one-time partnership rates. There remained a small positive association between prior one-time partnerships and the current number of one-time partnerships. Conclusions: Despite the preponderance of a low number of onetime partners, substantial variation in one-time partnership rates exists among young men who have sex with men and transgender women. Accordingly, focusing on high contact rate individuals alone may be insufficient to identify periods of highest risk. Future studies should use these estimates to more accurately model how volatility impacts HIV transmission and better understand how this variation influences intervention effectiveness. [ABSTRACT FROM AUTHOR]

Objective: This study used a Social network analysis (SNA) approach to describe HIV transmission and venue affiliations among social and sexual networks of young men who have sex with men (YMSM) in Houston, TX. Methods: A total of 34 YMSM indices aged 18–23 years and 23 of their network members were interviewed about their social and sexual networks and venues at which they met and spent time. Results: Participants reported information on 220 friends (mean age = 25.3 years) and 112 sexual partners (mean age = 26.3 years). Participants spent time with friends and sexual partners at similar venues but relied more heavily on social media and dating applications to meet sexual partners. Participants lived in zip codes consistent with high concentrations of HIV positivity. Popularly frequented clubs/gay bars were often 10–20 miles away, also in zip codes with high densities of seropositivity. Conclusion: Both friendship and sexual networks are large, diffuse, and not limited by geography. Participants came from areas with high rates of HIV/AIDS. The venues at which participants recruited sexual partners may present increased opportunities for HIV transmission. HIV prevention interventions should focus on the heightened risk of unknown HIV serostatus. [ABSTRACT FROM AUTHOR]

Background: The global COVID-19 pandemic has the potential to indirectly impact transmission dynamics and prevention of HIV and other sexually transmitted infections (STI). It is unknown what combined impact reductions in sexual activity and interruptions in HIV/STI services will have on HIV/STI epidemic trajectories.Methods: We adapted a model of HIV, gonorrhea, and chlamydia for a population of approximately 103 000 men who have sex with men (MSM) in the Atlanta area. Model scenarios varied the timing, overlap, and relative extent of COVID-19-related sexual distancing and service interruption within 4 service categories (HIV screening, preexposure prophylaxis, antiretroviral therapy, and STI treatment).Results: A 50% relative decrease in sexual partnerships and interruption of all clinical services, both lasting 18 months, would generally offset each other for HIV (total 5-year population impact for Atlanta MSM, -227 cases), but have net protective effect for STIs (-23 800 cases). If distancing lasted only 3 months but service interruption lasted 18 months, the total 5-year population impact would be an additional 890 HIV cases and 57 500 STI cases.Conclusions: Immediate action to limit the impact of service interruptions is needed to address the indirect effects of the global COVID-19 pandemic on the HIV/STI epidemic. [ABSTRACT FROM AUTHOR]

Contemporary strategies to curtail the emergence of antimicrobial resistance in Neisseria gonorrhoeae include screening for and treating asymptomatic infections in high-prevalence populations in whom antimicrobial drug–resistant infections have typically emerged. We argue that antimicrobial resistance in these groups is driven by a combination of dense sexual network connectivity and antimicrobial drug exposure (for example, through screen-and-treat strategies for asymptomatic N. gonorrhoeae infection). Sexual network connectivity sustains a high-equilibrium prevalence of N. gonorrhoeae and increases likelihood of reinfection, whereas antimicrobial drug exposure results in selection pressure for reinfecting N. gonorrhoeae strains to acquire antimicrobial resistance genes from commensal pharyngeal or rectal flora. We propose study designs to test this hypothesis.

Objective: Using mixed methods, we explored properties of long-haul truckers' social networks potentially influencing STI/BBI acquisition and transmission. Methods: We recruited inner-city drug and sex network members (N = 88) for interviews. Blood and urine samples and vaginal swabs were collected to test for STIs/BBIs. Data were collected on participants' role in the network (trucker, sex worker, or intermediary), sexual and substance-use behaviors, and dyadic relationships with drug and/or sex contacts. We analyzed network data using UCINET. Results: Data revealed 2 major network clusters (58 male truckers, 6 male intermediaries, and 24 female sex workers; 27.3% STI/BBI positive). Overall, 18.8% of network members had more than one type of risky relationship with the same person (multiplexity), 11.4% of dyads were between 2 STI/BBI positive people (assortative mixing), 36.4% were between one STI/BBI positive person and one negative person (disassortative mixing), 44.3% of people were connected to more than one person who was STI/BBI positive (concurrency), and 62.5% of nodes were just one path removed from an STI/BBI positive individual (bridging). Conclusion: Despite only 27.3% of the network being STI/BBI positive, our results revealed network characteristics (and potential intervention points) that amplify risk of disease spread within trucker-centered networks. [ABSTRACT FROM AUTHOR]

Objectives: We investigated the effects of an enhanced partner notification (PN) counselling intervention with the offer of provider-assisted referral among people diagnosed with STI in a Cape Town public clinic.Methods: Participants were adults diagnosed with STI at a community clinic. After the standard STI consultation, participants were randomly allocated in a 1:1:1 ratio to (1) 'HE': 20 min health education; (2) 'RR': 45 min risk reduction skills counselling; or (3) 'ePN': 45 min enhanced partner notification communication skills counselling and the offer of provider-assisted referral. The primary outcome was the incidence of repeat STI diagnoses during the 12 months after recruitment, and the secondary outcome was participants' reports 2 weeks after diagnosis of notifying recent partners. Incidence rate ratios (IRRs) were used to compare the incidence rates between arms using a Poisson regression model.Results: The sample included 1050 participants, 350 per group, diagnosed with STI between June 2014 and August 2017. We reviewed 1048 (99%) participant records, and identified 136 repeat STI diagnoses in the ePN arm, 138 in the RR arm and 141 in the HE arm. There was no difference in the annual incidence of STI diagnosis between the ePN and HE arms (IRR: 1.0; 95% CI 0.7 to 1.3), or between the RR and HE arms (IRR: 0.9; 95% CI 0.7 to 1.2). There was a greater chance of a partner being notified in the ePN condition compared with the HE condition, 64.3% compared with 53.8%, but no difference between the RR and HE arms.Conclusions: PN counselling and education with provider-assisted services has the potential to change the behaviour of people diagnosed with STIs, increasing the number of partners they notify by more than 10%. However, these changes in behaviour did not lead to a reduction of repeat STI diagnoses.Trial Registration Number: PACTR201606001682364. [ABSTRACT FROM AUTHOR]

Background: Sexual network degree, a count of ongoing partnerships, plays a critical role in the transmission dynamics of human immunodeficiency virus and other sexually transmitted infections. Researchers often quantify degree using self-reported cross-sectional data on the day of survey, which may result in bias because of uncertainty about future sexual activity.Methods: We evaluated the bias of a cross-sectional degree measure with a prospective cohort study of men who have sex with men (MSM). At baseline, we asked men about whether recent sexual partnerships were ongoing. We confirmed the true, ongoing status of those partnerships at baseline at follow-up. With logistic regression, we estimated the partnership-level predictors of baseline measure accuracy. With Poisson regression, we estimated the longitudinally confirmed degree as a function of baseline predicted degree.Results: Across partnership types, the baseline ongoing status measure was 70% accurate, with higher negative predictive value (91%) than positive predictive value (39%). Partnership exclusivity and racial pairing were associated with higher accuracy. Baseline degree generally overestimated confirmed degree. Bias, or number of ongoing partners different than predicted at baseline, was -0.28 overall, ranging from -1.91 to -0.41 for MSM with any ongoing partnerships at baseline. Comparing MSM of the same baseline degree, the level of bias was stronger for black compared with white MSM, and for younger compared with older MSM.Conclusions: Research studies may overestimate degree when it is quantified cross-sectionally. Adjustment and structured sensitivity analyses may account for bias in studies of human immunodeficiency virus or sexually transmitted infection prevention interventions. [ABSTRACT FROM AUTHOR]

Objective: We aimed to characterise gonorrhoea transmission patterns in a diverse urban population by linking genomic, epidemiological and antimicrobial susceptibility data.Methods: Neisseria gonorrhoeae isolates from patients attending sexual health clinics at Barts Health NHS Trust, London, UK, during an 11-month period underwent whole-genome sequencing and antimicrobial susceptibility testing. We combined laboratory and patient data to investigate the transmission network structure.Results: One hundred and fifty-eight isolates from 158 patients were available with associated descriptive data. One hundred and twenty-nine (82%) patients identified as male and 25 (16%) as female; four (3%) records lacked gender information. Self-described ethnicities were: 51 (32%) English/Welsh/Scottish; 33 (21%) white, other; 23 (15%) black British/black African/black, other; 12 (8%) Caribbean; 9 (6%) South Asian; 6 (4%) mixed ethnicity; and 10 (6%) other; data were missing for 14 (9%). Self-reported sexual orientations were 82 (52%) men who have sex with men (MSM); 49 (31%) heterosexual; 2 (1%) bisexual; data were missing for 25 individuals. Twenty-two (14%) patients were HIV positive. Whole-genome sequence data were generated for 151 isolates, which linked 75 (50%) patients to at least one other case. Using sequencing data, we found no evidence of transmission networks related to specific ethnic groups (p=0.64) or of HIV serosorting (p=0.35). Of 82 MSM/bisexual patients with sequencing data, 45 (55%) belonged to clusters of ≥2 cases, compared with 16/44 (36%) heterosexuals with sequencing data (p=0.06).Conclusion: We demonstrate links between 50% of patients in transmission networks using a relatively small sample in a large cosmopolitan city. We found no evidence of HIV serosorting. Our results do not support assortative selectivity as an explanation for differences in gonorrhoea incidence between ethnic groups. [ABSTRACT FROM AUTHOR]

Copyright of AIDS & Behavior is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Male sex workers (MSWs) are at increased risk of HIV infection in the United States. Research is limited on sexual and drug use network characteristics of MSWs. Setting: Community-based organization and health center in 2 US Northeast cities. Methods: One hundred MSWs completed a behavioral assessment and sexual and drug network inventory. Using dyadic analyses, we assessed whether network characteristics, including sex worker-male client age, race, and HIV status homophily and risk multiplexity (ie, overlap in druguse and sex networks), were associated with condom use. Results: MSW participants' mean age was 33.6. Two-thirds identified as Black or Latino, 12% identified as heterosexual, and 90% reported recent drug use. Participants reported an average of 5.3 male clients in the past month (SD = 3.4), and having anal sex with 74% of these clients, at a rate of 2.2 times per month (SD = 4.6). Participants reported inconsistent condom use during anal sex with 53% of clients. In multivariable models, inconsistent condom use was more common in relationships with presumed HIV status homophily [odds ratio (OR): 1.25; 95% confidence interval (CI): 1.07 to 1.46] and sexual and drug network multiplexity (OR: 1.19; 95% CI: 1.09 to 1.30); and less common within relationships where the client is older than the MSW participant (OR: 0.83; 95% CI: 0.74 to 0.93). Number of multiplex relationships was positively associated with number of condomless anal sex acts with male clients (incidence rate ratio: 1.35; 95% CI: 1.19 to 1.54). Conclusions: Network characteristics may contribute to disproportionate HIV risk among MSWs. Modeling studies should include network characteristics when simulating HIV transmission, and future HIV interventions should address the role of networks. [ABSTRACT FROM AUTHOR]

Objectives: Little is known about the sexual networks of young transwomen, leaving a major gap in what we know about transmission dynamics and the elevated rates of HIV in this population. The objective of this study was to understand partnership-level factors associated with condomless anal sex among young transwomen.Methods: A secondary data analysis of the sexual partnerships of young transwomen was conducted using baseline data from the SHINE study. Generalised estimating equation logistic regressions were used to assess for partnership-level associations between partnership type, age, injection drug use and racial concordance, HIV seroconcordance, sexual role and condomless receptive (CRAI) and insertive anal intercourse (CIAI).Results: Our analysis included 187 young transwomen that reported a total of 464 sexual partnerships where they had at least one episode of anal sex in the past 6 months. We found casual (n=232 or 50%) and commercial partnerships (n=106 or 22.8%) to be significantly associated with a lower odds of CIAI (OR=0.53, 95% CI 0.32 to 0.86 and OR=0.39, 95% CI 0.18 to 0.82) and CRAI (OR=0.30, 95% CI 0.19 to 0.47 and OR=0.35, 95% CI 0.2 to 0.62) compared with main partnerships (n=126 or 27.2%). Additionally, HIV-positive seroconcordant (n=25 or 5.4%, OR=4.05, 95% CI 1.44 to 11.40) and injection-drug using partnerships (n=25 or 5.4%, OR=3.66, 95% CI 1.34 to 9.95) were found to be significantly associated with an increased odds of CIAI among participants compared with HIV-negative seroconcordant (n=330 or 71.1%) and non-using partnerships (n=338 or 72.8%), respectively.Conclusion: Young transwomen, like other populations, engage in condomless sex more often with main than casual and commercial partners, suggesting a need for interventions that address sexual practices with steady main partners. [ABSTRACT FROM AUTHOR]

A review article presents theoretical basics of the development of innovative STI prevention programs for high-risk groups Urgent need for integrated multidisciplinary preventive strategies aimed at correcting risky behaviors and adapted for the particular vulnerable populations is justified.

Background: Despite high rates of HIV transmission among men who have sex with men (MSM) in Lima, Peru, limited data exist on the sexual network characteristics or risk factors for secondary HIV transmission among MSM with uncontrolled HIV infection. We report the frequency of serodiscordant, condomless anal intercourse (CAI) and associated sexual network characteristics among MSM in Lima with detectable HIV viremia and compare to those with undetectable viremia., Methods: This cross-sectional analysis includes MSM who tested positive for HIV-1 during screening for a trial of partner management and STI control (June 2022-January 2023). Participants were tested for HIV, gonorrhoea, chlamydia, and syphilis, and completed questionnaires on their demographic characteristics, sexual identity and behaviour, sexual network structures and engagement in HIV care., Findings: Of 665 MSM, 153 (23%) had detectable (>200 copies/mL) viremia. 75% (499/662) of men living with HIV were previously diagnosed, with 94% (n = 469/499) reporting that they were on ART, and 93% (n = 436/469) virally suppressed. 96% (n = 147/153) of men with detectable viremia reported serodiscordant CAI with at least one of their last three sexual partners, and 74% (n = 106/144) reported the same with all three of their recent partners. In contrast, 62% (n = 302/489) of men with undetectable viral load reported serodiscordant CAI with all of their last three partners (p < 0.01)., Interpretation: 23% of men living with HIV in Peru had detectable viremia, of whom almost all (96%) reported recent serodiscordant CAI. The primary gap in the HIV care cascade lies in awareness of HIV serostatus, suggesting that improved access to HIV testing could be a key prevention strategy in Peru., Funding: Funding for this study was provided by NIH/NIMH grants R01 MH118973 (PI: Clark) and R25 MH087222 (PI: Clark)., Competing Interests: None of the authors on this paper have financial or other conflicts of interest to disclose., (© 2024 The Authors.)

Black men who have sex with men (MSM) continue to experience disproportionately high HIV incidence rates relative to their white peers. Yet, Black MSM do not report higher levels of sexual risk behavior, and contextual factors such as access to care and sexual networks only partially explain these disparities. However, risk misclassification could help explain this paradox, if measurement biases systematically underestimate sexual risk behavior among Black MSM relative to their peers. The current study examined variation in sexual partnership corroboration in the RADAR study, a large and diverse cohort of young MSM and transgender women. Network data were elicited regarding all sexual partners in the prior 6 months, including instances where participants reported other participants as sexual partners. Using these data, anal and condomless anal sex partners were separately examined using a series of exponential random graph models to estimate the rate of corroboration of sexual connections between participants and examine whether this parameter varied by race/ethnicity. For both types of behavior, providing separate estimates for corroboration across race/ethnicity groups reduced model fit and did not significantly vary across groups. Accordingly, we found no evidence of measurement bias by race/ethnicity in the current data. However, overall rates of corroboration (41.2-50.3%) were low, suggesting substantial levels of measurement error. Accordingly, it is vital that researchers continue to improve upon methods to measure risk behavior in order to maximize their validity. We discuss the implications of these findings, including potential alternative causes of risk misclassification (e.g., sampling bias) and future directions to reduce measurement error. [ABSTRACT FROM AUTHOR]

Objectives: Geosocial networking application specific to men who have sex with men (MSM) (gay app) has revolutionised the social networking of MSM globally, much concern was raised over its linkage to HIV/syphilis risk. This study sought to examine the association between use of gay app and sexual behaviours and HIV/syphilis risk among Chinese MSM.Methods: Eligible MSM were recruited through combined offline methods from 2015 to 2017 in Shenzhen, China, with data collected including demographics, sexual behaviours, app use, recreational drug use and HIV testing. All participants are required to sign a written informed consent and take a confidential HIV and syphilis testing.Results: The prevalence of app use among non-commercial MSM (NcMSM) has rapidly increased from 12.5% in 2015 to 52.6% in 2017. The primary four apps used were Blued (97.2%), Aloha (18.4%), Jack'd (14.1) and Zank (14.1%). After controlling for confounders, HIV prevalence was still significantly lower among app users than non-app users (adjusted odds ratios [AOR]: 0.77, 95% CI 0.61 to 0.97), yet the lower prevalence of syphilis was not significant (AOR: 0.97, 95% CI 0.76 to 1.23). App-using NcMSM were more likely to be younger, unmarried, self-identified as homosexuality and having higher education level and income than non-app-using NcMSM. App-using NcMSM had higher rate of consistent condom use and HIV testing, higher level of knowledge on HIV/AIDS prevention and condom use; however, they were more likely to have multiple sexual partners, practice receptive role in anal sex and use recreational drug.Conclusions: App-using NcMSM are more likely to have sexual risk behaviours as well as risk-reduction behaviours such as consistent condom use and HIV testing. Scaled-up and innovative venue-based HIV interventions are warranted for these high-risk MSM frequent social venues with less condom use and fewer HIV tests. Meanwhile, gay app should alternatively serve as an intervention and education platform for the MSM hard-to-reach via venue-based approaches. [ABSTRACT FROM AUTHOR]

Recent work indicates that social structure has extensive implications for patterns of sexual selection and sexual conflict. However, little is known about the individual variation in social behaviours linking social structure to sexual interactions. Here, we use network analysis of replicate polygynandrous groups of red junglefowl (Gallus gallus) to show that the association between social structure and sexual interactions is underpinned by differential female sociality. Sexual dynamics are largely explained by a core group of highly social, younger females, which are more fecund and more polyandrous, and thus associated with more intense postcopulatory competition for males. By contrast, less fecund females from older cohorts, which tend to be socially dominant, avoid male sexual attention by clustering together and perching on branches, and preferentially reproduce with dominant males by more exclusively associating and mating with them. Collectively, these results indicate that individual females occupy subtly different social niches and demonstrate that female sociality can be an important factor underpinning the landscape of intrasexual competition and the emergent structure of animal societies. [ABSTRACT FROM AUTHOR]

Despite demonstrated efficacy, uptake of HIV pre-exposure prophylaxis (PrEP) remains low, particularly among high-risk demographics such as transgender women, Black men who have sex with men (BMSM), and young MSM (YMSM). Research thus far has largely focused on individual factors that may impede PrEP uptake in these demographics, leaving social network factors relatively unexplored. The present study used data collected from participants within RADAR, a longitudinal cohort study in Chicago focused on understanding the individual, dyadic, network, social, and biologic factors associated with HIV infection within YMSM. Of the 906 study participants who did not report an HIV diagnosis at baseline, 7.0% reported using PrEP in the prior 6 months. Recent PrEP use was associated with both individual-level (age and gender) and network-level factors (mean relationship strength, sexual network degree, etc.). These findings highlight the need to expand beyond focusing on individual-level drivers of PrEP uptake, as well as changing our understanding of who is most important within a network (centrality vs. strength of weak ties). Future work is needed to determine whether variables associated with PrEP uptake are similarly connected to PrEP adherence. [ABSTRACT FROM AUTHOR]

Objective: While men who have sex with men (MSM) are disproportionately affected by Peru's overlapping HIV and STI epidemics, there are few data on how partnership-level and network-level factors affect STI transmission in Peru. We explored partnership-level and network-level factors associated with gonorrhoea/chlamydia (Neisseria gonorrhoeae and/or Chlamydia trachomatis (NG/CT)) and/or syphilis infection among MSM in Peru.Methods: We present the results of a cross-sectional secondary analysis of MSM (n=898) tested for syphilis and NG/CT infection as part of the screening process for two STI control trials in Lima, Peru. Participants completed questionnaires on demographics, sexual identity and role, characteristics of their three most recent sexual partners (partner sexual orientation, gender, role, partnership type, partner-specific sexual acts) and 30-day sexual network characteristics (number of sexual partners, partnership types, frequency of anal/vaginal intercourse). Participants were tested for syphilis and urethral, rectal and oropharyngeal NG/CT. Differences in network characteristics were analysed with χ2 and Kruskal-Wallis tests.Results: Approximately 38.9% of participants had a new STI diagnosis (syphilis (rapid plasma reagin ≥16): 10.6%; NG/CT: 22.9%; syphilis-NG/CT coinfection: 5.4%). Condomless anal intercourse (CAI) was not significantly associated with an STI diagnosis. Gay-identified participants with exclusively homosexual networks had a higher prevalence of STIs (47.4%) than gay-identified MSM with only heterosexual/bisexual partners (34.6%, p=0.04), despite reporting fewer sexual partners (any partners: 2, 1-4 vs 3, 2-6; p=0.001; casual partners: 1, 0-3 vs 2, 1-4; p=0.001) and more stable partnerships (1, 0-1 vs 0, 0-1; p=0.003) in the last month.Conclusions: Network size and the number of casual sexual partners were associated with NG/CT infection among MSM in Peru. Despite reporting fewer sexual risk behaviours (smaller network size, more stable partnerships, less CAI), MSM with homosexual-only sexual networks had a higher prevalence of NG/CT and syphilis. These findings suggest network composition among MSM in Peru plays an important role in the risk for STI acquisition. [ABSTRACT FROM AUTHOR]

Large disparities exist in HIV across racial and ethnic populations—with Black and Latino populations disproportionately affected. This study utilizes a large cohort of young men who have sex with men (YMSM) to examine how race and ethnicity drive sexual partner selection, and how those with intersecting identities (Latinos who identify as White or Black) differ from Latinos without a specific racial identification (Latinos who identify as "Other"). Data come from YMSM (N = 895) who reported on sexual partners (N = 3244). Sexual mixing patterns differed substantially by race and ethnicity. Latinos who self-identified as "Black" reported mainly Black partners, those who self-identified as "White" predominantly partnered with Whites, while those who self-identified as "Other" mainly partnered with Latinos. Results suggested that Black-Latino YMSM are an important population for prevention, as their HIV prevalence neared that of Black YMSM, and their patterns of sexual partnership suggested that they may bridge Black YMSM and Other-Latino YMSM populations. [ABSTRACT FROM AUTHOR]

Les femmes et les hommes migrant‑e‑s d’Afrique subsaharienne sont très touchés par l’épidémie de VIH-SIDA en France. En mobilisant une enquête quantitative menée en 2005 auprès de 973 femmes et 901 hommes nés en Afrique subsaharienne et vivant en Île-de-France, cet article se propose de montrer que la ségrégation des réseaux sexuels et le multipartenariat contribuent à rendre compte de la diffusion de l’épidémie parmi ces migrant‑e‑s. La ségrégation des réseaux sexuels conduit à des relations entre des migrant‑e‑s originaires de pays à faible prévalence et à prévalence élevée. En outre, les hommes et les femmes de cette enquête n’ont pas les mêmes réseaux sexuels : les femmes ont plus souvent des partenaires d’Afrique subsaharienne et ont également plus souvent des partenaires sexuels ayant plus de partenaires qu’elles, ce qui peut entraîner des situations d’exposition au risque majorée pour les femmes. Quant aux hommes, ils sont engagés dans des relations simultanées de longue durée, ce qui peut constituer un contexte propice à la transmission.

Background: There is a large and persistent racial disparity in STI in the U.S. which has placed non-Hispanic-Blacks at disproportionately high risk. We tested a hypothesis that both individual-level risk factors (partner number, anal sex, condom use) and local-network features (concurrency and assortative mixing by race) combine to account for the association between race and chlamydia status. Methods: Data from the Longitudinal Survey of Adolescent Health Wave III were used. Chlamydia status was determined using biomarkers. Individual-level risk behaviors were self-reported. Network location variables for concurrency and assortative mixing were imputed using egocentrically sample data on sexual partnerships. Results: After controlling for demographic attributes including age, sex, marital status, education and health care access there remained a strong association between race and chlamydia status (OR = 5.23, 95% CI [3.83–7.15], p .05 for Non-Hispanic Blacks).

HIV is transmitted in social and sexual relationships, and HIV transmission risks, as well as protective actions, are evolving as HIV epidemics unfold. The current focus of HIV prevention is centered on antiretroviral medications used to reduce HIV infectiousness in persons already infected with HIV [treatment as prevention (TasP)]. The same medications used to treat infected persons can also be used by uninfected persons as pre-exposure prophylaxis (PrEP) to reduce the infectivity of HIV. Both PrEP and TasP are effective when adherence is high and individuals do not have co-occurring sexually transmitted infections. HIV prevention is most effective and efficient when delivered within sexual networks with high HIV prevalence. Specific network characteristics are recognized as important facilitators of HIV transmission; these characteristics include the degree of similarity among network members (homophily), gender role norms, and belief systems. Since 2011, HIV risk has been redefined based on infectiousness and infectivity, ushering in a new era of HIV prevention with the potential to end HIV epidemics. [ABSTRACT FROM AUTHOR]

Highlights • Increasing concurrency increases prevalence, making STIs harder to control. • Models with and without concurrency can be matched to prevalence data. • Models matched to data give similar predictions on required levels of vaccination. • Accurate models of concurrency may not be needed to reliably forecast STI control. Abstract Sexually transmitted infections (STIs) are a globally increasing public health problem. Mathematical models, carefully matched to available epidemiological and behavioural data, have an important role to play in predicting the action of control measures. Here, we explore the effect of concurrent sexual partnerships on the control of a generic STI with susceptible-infected-susceptible dynamics. Concurrency refers to being in more than one sexual partnership at the same time, and is difficult to measure accurately. We assess the impact of concurrency through the development of three nested pair-formation models: one where infection can only be transmitted via stable sexual partnerships, one where infection can also be transmitted via casual partnerships between single individuals, and one where those individuals in stable partnerships can also acquire infection from casual partnerships. For each model, we include the action of vaccination before sexual debut to inform about the ability to control. As expected, for a fixed transmission rate, concurrency increases both the endemic prevalence of infection and critical level of vaccination required to eliminate the disease significantly. However, when the transmission rate is scaled to maintain a fixed endemic prevalence across models, concurrency has a far smaller impact upon the critical level of vaccination required. Further, when we also constrain the models to have a fixed number of new partnerships over time (both long-term and casual), then increasing concurrency can slightly decrease the critical level of vaccination. These results highlight that accurate measures and models of concurrency may not always be needed for reliable forecasts when models are closely matched to prevalence data. We find that, while increases in concurrency within a population are likely to generate public-health problems, the inclusion of concurrency may be unnecessary when constructing models to determine the efficacy of the control of STIs by vaccination. [ABSTRACT FROM AUTHOR]

Background: Men who have sex with men (MSM) continue to be disproportionately impacted globally by the HIV epidemic. Studies suggest that HIV self-testing (HIVST) is highly acceptable among MSM. Social network strategies to increase testing are effective in reaching MSM, particularly MSM of color, who may not otherwise test. We tested a social network-based strategy to distribute HIVST kits to African American MSM (AAMSM) and Latino MSM (LMSM). Setting: This study was conducted in Alameda County, California, a large, urban/suburban county with an HIV epidemic mirroring the national HIV epidemic. Methods: From January 2016 to March 2017, 30 AAMSM, LMSM, and transgender women were trained as peer recruiters and asked to distribute 5 self-test kits to MSM social network members and support those who test positive in linking to care. Testers completed an online survey after their test. We compared peer-distributed HIVST testing outcomes to outcomes from Alameda County's targeted, community-based HIV testing programs using x2 tests. Results: Peer-distributed HIVST to 143 social and sexual network members, of whom 110 completed the online survey. Compared with MSM who used the County's sponsored testing programs, individuals reached through the peer-based self-testing strategy were significantly more likely to have never tested for HIV (3.51% vs. 0.41%, P < 0.01) and to report a positive test result (6.14% vs. 1.49%, P < 0.01). Conclusion: Findings suggest that a network-based strategy for self-test distribution is a promising intervention to increase testing uptake and reduce undiagnosed infections among AAMSM and LMSM [ABSTRACT FROM AUTHOR]

Ethnic affiliation can define sociocultural boundaries and contribute to the HIV vulnerabilities faced by men who have sex with men (MSM). This study investigated the influence of ethnic affiliation on HIV vulnerabilities among MSM in North China. Our study analyzed a cross-sectional survey of MSM (n = 398) in two major North China cities. We examined associations between ethnic affiliation and (a) HIV status, (b) sexual behaviors and experiences, and (c) substance use. Compared to ethnic majority Han MSM: MSM belonging to ethnic minority groups of South China had significantly greater odds of HIV infection (AOR: 7.40; 95% CI: 2.33-23.47) and experience of forced sex (AOR: 3.27; 95% CI: 1.12-9.52). Compared to ethnic majority Han MSM, Ethnic Hui MSM had significantly lower odds of condomless anal sex (AOR: 0.41; 95% CI: 0.21-0.82) and significantly greater odds of circumcision (AOR: 2.62; 95% CI: 1.24-5.51). HIV prevalence and riskier sexual behaviors among MSM in China appear to vary significantly by ethnic affiliation. Current epidemiological practices of aggregating all ethnic minority groups in China into a single category may be masking important interethnic differences in HIV risk, and precluding opportunities for more culturally appropriate interventions. [ABSTRACT FROM AUTHOR]

Background: Partner notification is an important component of public health test and treat interventions. To enhance this essential function, we assessed the potential for molecular methods to supplement routine partner notification and corroborate HIV networks. Methods: All persons diagnosed with HIV infection in Wake County, NC, during 2012-2013 and their disclosed sexual partners were included in a sexual network. A data set containing HIV-1 pol sequences collected in NC during 1997-2014 from 15,246 persons was matched to HIV-positive persons in the network and used to identify putative transmission clusters. Both networks were compared. Results: The partner notification network comprised 280 index cases and 383 sexual partners and high-risk social contacts (n = 131 HIV- positive). Of the 411 HIV-positive persons in the partner notification network, 181 (44%) did not match to a HIV sequence, 61 (15%) had sequences but were not identified in a transmission cluster, and 169 (41%) were identified in a transmission cluster. More than half (59%) of transmission clusters bridged sexual network partnerships that were not recognized in the partner notification; most of these clusters were dominated by men who have sex with men. Conclusions: Partner notification and HIV sequence analysis provide complementary representations of the existent partnerships underlying the HIV transmission network. The partner notification network components were bridged by transmission clusters, particularly among components dominated by men who have sex with men. Supplementing the partner notification network with phylogenetic data highlighted avenues for intervention. [ABSTRACT FROM AUTHOR]

HIV viral load (VL) predicts both transmission potential and rate of disease progression. For reasons that are still not fully understood, the set point viral load (SPVL) established after acute infection varies across individuals and populations. Previous studies have suggested that populationmean SPVL (MSPVL) has evolved near an optimumthat reflects a trade-off between transmissibility and host survival. Sexual network structures affect rates of potential exposure during different within-host phases of infectionmarked by different transmission probabilities, and thus affect the number and timing of transmission events. These structures include relational concurrency, which has been argued to explain key differences in HIV burden across populations.We hypothesize that concurrency will alter the fitness landscape for SPVL in ways that differ from other network features whose impacts accrue at other times during infection. To quantitatively test this hypothesis, we developed a dynamic, stochastic, data-driven networkmodel of HIV transmission, and evolution to assess the impact of key sexual network phenomena onMSPVL evolution. Experiments were repeated in sensitivity runs thatmade different assumptions about transmissibility during acute infection, SPVL heritability, and the functional formof the relationship between VL and transmissibility. For ourmain transmission model, scenarios yielded MSPVLs ranging from4.4 to 4.75 log10 copies/ml, coveringmuch of the observed empirical range. MSPVL evolved to be higher in populations with high concurrency and shorter relational durations, with values varying over a clinically significant range. In linear regression analyses on these and other predictors,main effects were significant (P < 0.05), as were interaction terms, indicating that effects are interdependent. We also noted a strong correlation between two key emergent propertiesmeasured at the end of the simulations--MSPVL and HIV prevalence--most clearly for phenomena that affect transmission networks early in infection. Controlling for prevalence, high concurrency yielded higherMSPVL than other network phenomena. Interestingly, we observed lower prevalence in runs in which SPVL heritability was zero, indicating the potential for viral evolution to exacerbate disease burden over time. Future efforts to understand empirical variation in MSPVL should consider local HIV burden and basic sexual behavioral and network structure. [ABSTRACT FROM AUTHOR]

Background: Substantial racial disparities exist in HIV infection among young men who have sex with men (YMSM). However, evidence suggests black YMSM do not engage in greater levels of risk behavior. Sexual networks may help explain this paradox. This study used egocentric exponential random graph models to examine variation in concurrency (ie, 2 or more simultaneous partners) and homophily (ie, same race/ethnicity partners) across race/ethnicity groups in a diverse sample of YMSM. Methods: Data for this study come from a longitudinal cohort study of YMSM. Participants (n = 1012) provided data regarding their sexual contacts during the 6 months before their first study visit. A series of egocentric exponential random graph models examined how providing separate estimates for homophily and concurrency parameters across race/ethnicity improved the fit of these models. Networks were simulated using these parameters to examine how local network characteristics impact risk at the whole network level. Results: Results indicated that homophily, but not concurrency, varied across race/ethnicity. Black participants witnessed significantly higher race/ethnicity homophily compared with white and Latino peers. Extrapolating from these models, black individuals were more likely to be in a connected component with an HIV-positive individual and closer to HIV-positive individuals. However, white individuals were more likely to be in large connected components. Conclusions: These findings suggest that high racial homophily combined with existing disparities in HIV help perpetuate the spread of HIV among black YMSM. Nonetheless, additional work is required to understand these disparities given that homophily alone cannot sustain them indefinitely. [ABSTRACT FROM AUTHOR]

UNAIDS proposed a set of core indicators for monitoring changes in the worldwide AIDS epidemic. This paper explores the validity and effectiveness of the ‘multiple sexual partners’ core indicator, which is only partially captured with current available data. The paper also suggests an innovative approach for collecting more informative data that can be used to provide an accurate measure of the UNAIDS's ‘multiple sexual partners’ core indicator. Specifically, the paper addresses three major limitations associated with the indicator when it is measured with respondents’ sexual behaviors. First, the indicator assumes that a person's risk of contracting HIV/AIDS/STIs is merely a function of his/her own sexual behavior. Second, the indicator does not account for a partner's sexual history, which is very important in assessing an individual's risk level. Finally, the 12-month period used to define a person's risks can be misleading, especially because HIV/AIDS theoretically has a period of latency longer than a year. The paper concludes that, programmatically, improvements in data collection are a top priority for reducing the observed bias in the ‘multiple sexual partners’ core indicator.

Introduction. Sociometric studies based on the evaluation of structures forming interpersonal network earned widespread recognition in sexually transmitted diseases (STD) epidemiology. Objective . The aim of this work is to assess the importance of epidemiological studies of infection sources, contacts and the network of connections created by them in the detection of early syphilis infections in the Bialystok province (1989–2010). Material and methods . Material for the study was the documentation of 316 patients diagnosed with early syphilis and 265 registered contacts declared by them, observed and treated in STD clinics. Epidemiological assessment was based on the basic parameters. Social Network Analysis was based on parameters of Seidman k-core. Results . Epidemiological studies showed that 67.4% of 316 patients with early syphilis reported registered contacts (index 0.83). 87.5% of these contacts have been tested and in more than a half (53%) of them early syphilis has been diagnosed. The remaining 16.8% of patients (with their consent) were subjected to prophylactic treatment, and the rest (after an appropriate time of control) were considered to be not infected. Thirty-three persons (12.5%) could not be found. Social Network Analysis of 316 patients showed that as many as 176 (53.7%) did not show any links in epidemiologic investigations. One hundred and twenty-two patients had 2–6 personal links without creating a k-core. Only in 1995, during a syphilis microepidemic (in town C), has a typical network of sexual relationships with a k-core consisting of 18 patients been revealed. Conclusions . The results of the study indicate major shortcomings in the work of STD clinics in Podlaskie Province in the years 1999–2010. Analysis of the structure of sexual networks is a valuable method for enriching the methodology of epidemiological investigations in detecting sources of infection and their contacts, provided very detailed epidemiological investigations are performed and there is close cooperation with other STD clinics. Social Network Analysis of infection sources and their sexual contacts allows forecasting the morbidity, as well as selecting groups according to their sexual behavior, regions in which infections may appear and patients’ social and ethnic group.

Analysis of sexual history data intended to describe sexual networks presents many challenges arising from the fact that most surveys collect information on only a very small fraction of the population of interest. In addition, partners are rarely identified and responses are subject to reporting biases. Typically, each network statistic of interest, such as mean number of sexual partners for men or women, is estimated independently of other network statistics. There is, however, a complex relationship among networks statistics; and knowledge of these relationships can aid in addressing concerns mentioned earlier. We develop a novel method that constrains a posterior predictive distribution of a collection of network statistics in order to leverage the relationships among network statistics in making inference about network properties of interest. The method ensures that inference on network properties is compatible with an actual network. Through extensive simulation studies, we also demonstrate that use of this method can improve estimates in settings where there is uncertainty that arises both from sampling and from systematic reporting bias compared with currently available approaches to estimation. To illustrate the method, we apply it to estimate network statistics using data from the Chicago Health and Social Life Survey. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]