Testing Together Behaviors in Secondary Distribution of HIV/Syphilis Self-testing Program Among Men Who have Sex with Men in China

HIV self-testing (HIVST) is recommended as a promising way to increase HIV testing uptake among MSM. MSM sometimes used HIVST kits together with their sexual partners or friends. However, limited data was reported on MSM's testing together behaviors with sexual partners and non-sexual contacts. Data were collected among MSM in China from June 2018 to June 2019. Eligible participants (referred to as "index participants") finished a baseline survey and applied for HIVST kits. They were encouraged to distribute the kits to other people (referred to as "alters"). Index participants finished a 3-month follow-up survey on the distribution and usage of the kits. Alters finished an online survey on the usage of HIVST kits after they returned the photographed testing results. Results were reported based on index participants and alters, respectively. Based on follow-up data, 138 index participants successfully motivated others for HIVST, most of them (77.5%) tested together with at least one alter. Around half of alters (52.3%) reported testing together with index participants. Index participants distributed more HIVST kits to friends than sexual partners. MSM who had ever tested for HIV were more likely to test together. Our study demonstrated that the testing together behaviors during HIVST distribution among sexual partners and social network contacts were common. The social network-based approach is essential in promoting testing together and HIV status disclosure among MSM.

Partnership dynamics in mathematical models and implications for representation of sexually transmitted infections: a review

Mathematical models of sexually transmitted disease (STI) are increasingly relied on to inform policy, practice, and resource allocation. Because STI transmission requires sexual contact between two or more people, a model's ability to represent the dynamics of sexual partnerships can influence the validity of findings. This ability is to a large extent constrained by the model type, as different modeling frameworks vary in their capability to capture patterns of sexual contact at individual, partnership, and network levels. In this paper, we classify models into three groups: compartmental, individual-based, and statistical network models. For each framework, we describe the basic model structure and discuss key aspects of sexual partnership dynamics: how and with whom partnerships are formed, partnership duration and dissolution, and temporal overlap in partnerships (concurrency). We illustrate the potential implications of accurately accounting for partnership dynamics, but these effects depend on characteristics of both the population and pathogen; the combined impact of these partnership and epidemiologic dynamics can be difficult to predict. While each of the reviewed model frameworks may be appropriate to inform certain research or policy questions, modelers and consumers of models should carefully consider the implications of sexual partnership dynamics for the questions under study.

Using an agent-based sexual-network model to analyze the impact of mitigation efforts for controlling chlamydia

Chlamydia trachomatis (Ct) is the most reported sexually transmitted infection in the United States, with a major cause of infertility, pelvic inflammatory disease, and ectopic pregnancy among women. Despite decades of screening women for Ct, rates increase among young African Americans (AA). We create and analyze a heterosexual agent-based network model to help understand the spread of Ct. We calibrate the model parameters to agree with survey data showing Ct prevalence of 12% of the women and 10% of the men in the 15-25 year-old AA in New Orleans, Louisiana. Our model accounts for both long-term and casual partnerships. The network captures the assortative mixing of individuals by preserving the joint-degree distributions observed in the data. We compare the effectiveness of intervention strategies based on randomly screening men, notifying partners of infected people, which includes partner treatment, partner screening, and rescreening for infection. We compare the difference between treating partners of an infected person both with and without testing them. We observe that although increased Ct screening, rescreening, and treating most of the partners of infected people will reduce the prevalence, these mitigations alone are not sufficient to control the epidemic. The current practice is to treat the partners of an infected individual without first testing them for infection. The model predicts that if a sufficient number of the partners of all infected people are tested and treated, then there is a threshold condition where the epidemic can be mitigated. This threshold results from the expanded treatment network created by treating an individual's infected partners' partners. Although these conclusions can help design future Ct mitigation studies, we caution the reader that these conclusions are for the mathematical model, not the real world, and are contingent on the validity of the model assumptions.

Increased HIV diagnoses in West Virginia counties highly vulnerable to rapid HIV dissemination through injection drug use: a cautionary tale

PURPOSE

To investigate HIV transmission potential from a cluster of HIV infections among men who have sex with men to persons who inject drugs in 15 West Virginia counties. These counties were previously identified as highly vulnerable to rapid HIV dissemination through injection drug use (IDU) associated with high levels of opioid misuse.

METHODS

We interviewed persons with 2017 HIV diagnoses about past-year risk behaviors and elicited sexual, IDU, and social contacts. We tested contacts for HIV and assessed risk behaviors. To determine HIV transmission potential from persons with 2017 diagnoses to persons who inject drugs, we assessed viral suppression status, HIV status of contacts, and IDU risk behaviors of persons living with HIV and contacts.

RESULTS

We interviewed 78 persons: 39 with 2017 diagnoses and 39 contacts. Overall, 13/78 (17%) injected drugs in the past year. Of 19 persons with 2017 diagnoses and detectable virus, 9 (47%) had more than or equal to 1 sexual or IDU contacts of negative or unknown HIV status. During the past year, 2/9 had injected drugs and shared equipment, and 1/9 had more than or equal to 1 partner who did so.

CONCLUSIONS

We identified IDU risk behavior among persons with 2017 diagnoses and their contacts. West Virginia HIV prevention programs should continue to give high priority to IDU harm reduction.

Geographic mobility and potential bridging for sexually transmitted infections in Agbogbloshie, Ghana

Short-term mobility can significantly influence the spread of infectious disease. In order for mobile individuals to geographically spread sexually transmitted infections (STIs), individuals must engage in sexual acts with different partners in two places within a short time. In this study, we considered the potential of mobile individuals as bridge populations - individuals who link otherwise disconnected sexual networks and contributed to ongoing STI transmission. Using monthly retrospective panel data, we examined associations between short-term mobility and sexual partner concurrency in Agbogbloshie, Ghana. We also examined bridging by the location of sex acts and the location of sexual partners in concurrent triads, and whether mobile individuals from our sample were more likely to be members of geographic bridging triads. Although reported rates of sexual partnership concurrency were much higher for men compared to women, mobility was only associated with increased concurrency for women. Additionally, this association held for middle-distance mobility and short-duration trips for women. Taking into account the location of sex acts and the location of sexual partners, about 22% of men (21.7% and 22.4% for mobile and non-mobile men, respectively) and only 3% of women (1.4% and 3.3% for mobile and non-mobile women, respectively) were potential bridges for STIs over the last year. Our results highlight the gendered nature of mobility and sexual risk behavior, reflecting the normative social context that encourages women to conceal certain types of sexual behavior.

Strong association between the prevalence of bacterial vaginosis and male point-concurrency

OBJECTIVE

The prevalence of bacterial vaginosis (BV) differs considerably between different populations, and individual-level risk factors such as number of sex partners seem unable to explain these differences. The effect of network-level factors, such as the prevalence of partner concurrency (the proportion of sexual partnerships that overlap in time as opposed to running sequentially) on BV prevalence has not hitherto been investigated.

STUDY DESIGN

We performed linear regression to assess the relationship between the prevalence of male concurrency and prevalence of BV in each of 11 countries for which we could obtain comparable data. The data for concurrency prevalence were taken from the WHO/Global Programme on AIDS (GPA) sexual behavioural surveys. BV prevalence rates were obtained from a systematic review of the global patterning of BV.

RESULTS

We found a strong relationship between the prevalence of male concurrency and BV prevalence (Pearson's R(2)=0.57; P=0.007).

CONCLUSIONS

The findings of a strong ecological-level association between BV and partner concurrency need to be replicated and augmented with different types of studies such as multilevel prospective studies tracking the incidence of BV and associated individual, partner and network level risk factors.