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After community transmission of monkeypox virus was identified in Europe, interviews of 45 case-patients from England indicated transmission in international sexual networks of gay and bisexual men since April 2022. Interventions targeting sex-on-premises venues, geospatial dating applications, and sexual health services are likely to be critical for outbreak control.

Men who have sex with men (MSM) are the most affected risk group in the United States' human immunodeficiency virus (HIV) epidemic. Sexual concurrency, the overlapping of partnerships in time, accelerates HIV transmission in populations and has been documented at high levels among MSM. However, concurrency is challenging to measure empirically and variations in assessment techniques used (primarily the date overlap and direct question approaches) and the outcomes derived from them have led to heterogeneity and questionable validity of estimates among MSM and other populations. The aim was to evaluate a novel Web-based and interactive partnership-timing module designed for measuring concurrency among MSM, and to compare outcomes measured by the partnership-timing module to those of typical approaches in an online study of MSM. In an online study of MSM aged ≥18 years, we assessed concurrency by using the direct question method and by gathering the dates of first and last sex, with enhanced programming logic, for each reported partner in the previous 6 months. From these methods, we computed multiple concurrency cumulative prevalence outcomes: direct question, day resolution / date overlap, and month resolution / date overlap including both 1-month ties and excluding ties. We additionally computed variants of the UNAIDS point prevalence outcome. The partnership-timing module was also administered. It uses an interactive month resolution calendar to improve recall and follow-up questions to resolve temporal ambiguities, combines elements of the direct question and date overlap approaches. The agreement between the partnership-timing module and other concurrency outcomes was assessed with percent agreement, kappa statistic (κ), and matched odds ratios at the individual, dyad, and triad levels of analysis. Among 2737 MSM who completed the partnership section of the partnership-timing module, 41.07% (1124/2737) of individuals had concurrent partners in the previous 6 months. The partnership-timing module had the highest degree of agreement with the direct question. Agreement was lower with date overlap outcomes (agreement range 79%-81%, κ range .55-.59) and lowest with the UNAIDS outcome at 5 months before interview (65% agreement, κ=.14, 95% CI .12-.16). All agreements declined after excluding individuals with 1 sex partner (always classified as not engaging in concurrency), although the highest agreement was still observed with the direct question technique (81% agreement, κ=.59, 95% CI .55-.63). Similar patterns in agreement were observed with dyad- and triad-level outcomes. The partnership-timing module showed strong concurrency detection ability and agreement with previous measures. These levels of agreement were greater than others have reported among previous measures. The partnership-timing module may be well suited to quantifying concurrency among MSM at multiple levels of analysis.

Like many other social phenomena, prostitution is increasingly coordinated over the Internet. The online behavior affects the offline activity; the reverse is also true. We investigated the reported sexual contacts between 6,624 anonymous escorts and 10,106 sex buyers extracted from an online community from its beginning and six years on. These sexual encounters were also graded and categorized (in terms of the type of sexual activities performed) by the buyers. From the temporal, bipartite network of posts, we found a full feedback loop in which high grades on previous posts affect the future commercial success of the sex worker, and vice versa. We also found a peculiar growth pattern in which the turnover of community members and sex workers causes a sublinear preferential attachment. There is, moreover, a strong geographic influence on network structure--the network is geographically clustered but still close to connected, the contacts consistent with the inverse-square law observed in trading patterns. We also found that the number of sellers scales sublinearly with city size, so this type of prostitution does not, comparatively speaking, benefit much from an increasing concentration of people.

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 cross-sectional 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 12months, 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 20 male-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.

This article describes the structure of the adolescent romantic and sexual network in a population of over 800 adolescents residing in a midsized town in the midwestern United States. Precise images and measures of network structure are derived from reports of relationships that occurred over a period of 18 months between 1993 and 1995. The study offers a comparison of the structural characteristics of the observed network to simulated networks conditioned on the distribution of ties; the observed structure reveals networks characterized by longer contact chains and fewer cycles than expected. This article identifies the micromechanisms that generate networks with structural features similar to the observed network. Implications for disease transmission dynamics and social policy are explored. Reprinted by permission of the University of Chicago Press. © All rights reserved

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.

Young men who have sex with men are at increased risk for HIV. Research with older men and high-risk populations suggests that network dynamics may contribute to the spread of infectious disease and HIV, but little is known about the sexual networks of young men who have sex with men. Utilizing a unique dataset, this study presents novel descriptive data about the sexual networks of racially diverse 17- to 23-year-old young men who have sex with men. Additionally, individual, partner, and network characteristics of these young men who have sex with men were examined as potential drivers of HIV, STI, and unprotected intercourse. Results indicated several partner- and network-level factors associated with HIV and associated outcomes.

A challenge in evolutionary biology is to understand the operation of sexual selection on males in polyandrous groups, where sexual selection occurs before and after mating. Here, we combine fine-grained behavioral information (>41,000 interactions) with molecular parentage data to study sexual selection in replicated, age-structured groups of polyandrous red junglefowl, Gallus gallus. Male reproductive success was determined by the number of females mated (precopulatory sexual selection) and his paternity share, which was driven by the polyandry of his female partners (postcopulatory sexual selection). Pre- and postcopulatory components of male reproductive success covaried positively; males with high mating success also had high paternity share. Two male phenotypes affected male pre-and postcopulatory performance: average aggressiveness toward rival males and age. Aggressive males mated with more females and more often with individual females, resulting in higher sexual exclusivity. Similarly, younger males mated with more females and more often with individual females, suffering less intense sperm competition than older males. Older males had a lower paternity share even allowing for their limited sexual exclusivity, indicating they may produce less competitive ejaculates. These results show that—in these populations—postcopulatory sexual selection reinforces precopulatory sexual selection, consistently promoting younger and more aggressive males.

Background Young Black men who have sex with men (MSM) are disproportionately affected by HIV and STIs in North Carolina (NC). Behavior and STI prevalence in the sexual network affect transmission risk; network position may be a marker for risk. Methods We constructed the local sexual network from reportable HIV and syphilis cases diagnosed among Black men age 15–30 in north central NC from 2006–2009 (N = 1100); infected and uninfected contacts were included in the network. Bonacich power is an unbounded measure of network centrality derived from the number of contacts and number of contacts’ contacts. Higher Bonacich scores represent increased centrality in the network, while accounting for the centrality of an individual’s contacts. It is iterative, giving more weight to closer contacts. To assess the centrality of college status in the network, Bonacich scores and 95% confidence intervals (95% CI) were calculated for all college-age Black men (17–24 years) (n = 385). We computed t-tests and chi-square tests to measure score differences by college status for factors associated with HIV infection risk. Results Bonacich scores were normally distributed (range –57.5–62.2). Mean score was higher for college than non-college men (5.86 (95% CI: 4.69–7.04) v. 3.13 (95% CI: 2.51–3.76), P < 0.0001). College men were more likely to use dating sites and less likely to use marijuana than non-college men. Sexual orientation also differed significantly by college status: while the proportion of MSM was ∼70%, college men were more likely to be bisexual (24% v. 11%) and less likely to be heterosexual (7% v. 22%) compared to non-college men. College status was not associated with diagnosis, STI history, alcohol use, or having anonymous partners. Conclusion Young African-American college men are more central in this sexual network than young African-American men who are not in college, putting them at risk for HIV acquisition and transmission.

Background Understanding patterns of human papillomavirus (HPV) infection in partnerships is essential in exploring transmission of HPV in sexual networks. Risk factors for HPV infection have yet to be explored at the dyad level. We studied features that predict presence of HPV in a new sexual partnership. Methods We analysed data from the HITCH Cohort Study of recently-formed couples. Women aged 18–24 attending university/college in Montreal, Canada and their male partners were recruited in 2006–10. Self-collected vaginal swabs and clinician-obtained swabs from the penis and scrotum were tested for DNA of 36 HPV types. We analysed baseline data from 479 couples. HPV in a partnership was defined as the presence of 1 or more HPV types in either or both partners. We used Poisson regression to calculate prevalence ratios with 95% confidence intervals for candidate risk factors. Results Most women were unvaccinated (88%). 67% of partnerships harboured HPV. For 49% both partners were HPV+. Detection was associated with the combined total of the male’s and female’s lifetime partners; from 27.5% among couples who jointly had no more than 4 partners to 94.2% among couples with > 20. Couples reporting concurrent partners were 2.8 times (95% CI 1.7–4.5) more likely to have HPV compared to those with a 12-month gap since the last extra-dyadic partner but this effect disappeared after adjustment for number of partners. Couples who always or frequently used condoms with their previous partner(s) were 29% (95% CI 9–45%) less likely to have HPV after accounting for number of partners and gap length/concurrency. Conclusions Number of extra-dyadic partners (past or concurrent) predicts the likelihood of HPV in a partnership. Condoms may have some impact on limiting spread of HPV, although protection was incomplete. Epidemiologic monitoring of HPV in sexual networks is needed, particularly in populations with suboptimal HPV vaccine coverage.