Social Support Networks and HIV/STI Risk Behaviors Among Latino Immigrants in a New Receiving Environment.

The objectives of this study were to: (1) describe the quantity and quality of social support networks of Latino immigrants living in a new receiving environment, and (2) determine the role such networks play in their HIV/STI risk behaviors, including substance use. Double incentivized convenience sampling was used to collect egocentric social support network data on 144 Latino immigrants. Latent class analysis was used for data reduction and to identify items best suited to measure quality and quantity of social support. Moderate and high quantity and quality of social support were protective of HIV/STI sexual risk behavior compared to low quantity and quality of support, after adjustment for gender, years in New Orleans and residing with family. Neither measure of social support was associated with binge drinking. The findings suggest that increased quantity and quality of social support decrease HIV/STI sexual risk behaviors but do not influence binge drinking. Interventions that improve the quantity and quality of social support are needed for Latino immigrants.

A network intervention that locates and intervenes with recently HIV-infected persons: The Transmission Reduction Intervention Project (TRIP).

Early treatment, soon after infection, reduces HIV transmissions and benefits patients. The Transmission Reduction Intervention Project (TRIP) evaluated a network intervention to detect individuals recently infected (in the past 6 months). TRIP was conducted in Greece (2013-2015) and focused on drug injector networks. Based on HIV status, testing history, and the results of an assay to detect recent infections, TRIP classified drug injector "Seeds" into groups: Recent Seeds (RS), and Control Seeds with Long-term HIV infection (LCS). The network members of RS and LCS were traced for two steps. The analysis included 23 RS, 171 network members of the RS, 19 LCS, and 65 network members of the LCS. The per-seed number of recents detected in the network of RS was 5 times the number in the network of LCS (Ratio RS vs. LCS: 5.23; 95% Confidence Interval (CI): 1.54-27.61). The proportion of recents among HIV positives in the network of RS (27%) was approximately 3 times (Ratio RS vs. LCS: 3.30; 95% CI: 1.04-10.43) that in the network of LCS (8%). Strategic network tracing that starts with recently infected persons could support public health efforts to find and treat people early in their HIV infection.

The Role of Geographic and Network Factors in Racial Disparities in HIV Among Young Men Who have Sex with Men: An Egocentric Network Study.

The objective of this study was to characterize and compare individual and sexual network characteristics of Black, White, and Latino young men who have sex with men (YMSM) as potential drivers of racial disparities in HIV. Egocentric network interviews were conducted with 175 diverse YMSM who described 837 sex partners within 167 sexual-active egos. Sexual partner alter attributes were summarized by ego. Descriptives of ego demographics, sexual partner demographics, and network characteristics were calculated by race of the ego and compared. No racial differences were found in individual engagement in HIV risk behaviors or concurrent sexual partnership. Racial differences were found in partner characteristics, including female gender, non-gay sexual orientations, older age, and residence in a high HIV prevalence neighborhood. Racial differences in relationship characteristics included type of relationships (i.e., main partner) and strength of relationships. Network characteristics also showed differences, including sexual network density and assortativity by race. Most racial differences were in the direction of effects that would tend to increase HIV incidence among Black YMSM. These data suggest that racial disparities in HIV may be driven and/or maintained by a combination of racial differences in partner characteristics, assortativity by race, and increased sexual network density, rather than differences in individual's HIV risk behaviors.

Structural bridging network position is associated with HIV status in a younger Black men who have sex with men epidemic.

Younger Black men who have sex with men (BMSM) ages 16-29 have the highest rates of HIV in the United States. Despite increased attention to social and sexual networks as a framework for biomedical intervention, the role of measured network positions, such as bridging and their relationship to HIV risk has received limited attention. A network sample (N = 620) of BMSM respondents (N = 154) and their MSM and transgendered person network members (N = 466) was generated through respondent driven sampling of BMSM and elicitation of their personal networks. Bridging status of each network member was determined by a constraint measure and was used to assess the relationship between this bridging and unprotected anal intercourse (UAI), sex-drug use (SDU), group sex (GS) and HIV status within the network in South Chicago. Low, moderate and high bridging was observed in 411 (66.8 %), 81 (13.2 %) and 123 (20.0 %) of the network. In addition to age and having sex with men only, moderate and high levels of bridging were associated with HIV status (aOR 3.19; 95 % CI 1.58-6.45 and aOR 3.83; 95 % CI 1.23-11.95, respectively). Risk behaviors observed including UAS, GS, and SDU were not associated with HIV status, however, they clustered together in their associations with one another. Bridging network position but not risk behavior was associated with HIV status in this network sample of younger BMSM. Socio-structural features such as position within the network may be important when implementing effective HIV prevention interventions in younger BMSM populations.

Impact of social network characteristics on shelter use among street youth in San Francisco.

PURPOSE: We examined the cross-sectional and longitudinal association between social network characteristics and street youths' shelter use, a determinant of health outcomes for homeless youth. METHODS: We analyzed interview data from 138 street youth recruited through venue-based sampling in San Francisco, to assess the cross-sectional relationship between shelter use in youths' social networks and youths' reported shelter use. We also assessed the relationship between baseline network shelter use and shelter use at 6-month follow-up. RESULTS: Low proportions of street youth reported shelter use at baseline (38%) and follow-up (29.6%). Twenty-nine (26.9%) youth were in networks with shelter users at baseline, compared with 17 youth (15.7%) at follow-up. In cross-sectional analysis, youth in networks with shelter users had 5-fold increased odds of reporting shelter use (OR: 5.86, p = .006). A 1-person increase in the number of network shelter users was associated with 2-fold increased odds of youths' shelter use (OR: 2.16, p = .02). In longitudinal analysis, youth in networks with shelter users at baseline had nearly 5-fold increased odds of shelter use at follow-up (OR: 4.95, p = .01). A 1-person increase in the number of network shelter users at baseline was associated with 3-fold increased odds of shelter use at follow-up (OR: 3.15, p = .004). CONCLUSION: Shelter users seem to cluster together. Shelter use by extended network members was associated with increased odds of youths' own shelter use. Understanding how network behaviors influence street youths' health-related behaviors, such as shelter use, could inform network-based interventions encouraging service uptake among marginalized and hard-to-reach street youth populations.

Injection Drug Users' Involvement In Drug Economy: Dynamics of Sociometric and Egocentric Social Networks.

The purpose of this analysis was to examine the effect of social network cohesiveness on drug economy involvement, and to test whether this relationship is mediated by drug support network size in a sample of active injection drug users. Involvement in the drug economy was defined by self-report of participation in at least one of the following activities: selling drugs, holding drugs or money for drugs, providing street security for drug sellers, cutting/packaging/cooking drugs, selling or renting drug paraphernalia (e.g., pipes, tools, rigs), and injecting drugs in others' veins. The sample consists of 273 active injection drug users in Baltimore, Maryland who reported having injected drugs in the last 6 months and were recruited through either street outreach or by their network members. Egocentric drug support networks were assessed through a social network inventory at baseline. Sociometric networks were built upon the linkages by selected matching characteristics, and k-plex rank was used to characterize the level of cohesiveness of the individual to others in the social network. Although no direct effect was observed, structural equation modeling indicated k-plex rank was indirectly associated with drug economy involvement through drug support network size. These findings suggest the effects of large-scale sociometric networks on injectors' drug economy involvement may occur through their immediate egocentric networks. Future harm reduction programs for injection drug users (IDUs) should consider providing programs coupled with economic opportunities to those drug users within a cohesive network subgroup. Moreover, individuals with a high connectivity to others in their network may be optimal individuals to train for diffusing HIV prevention messages.

The analysis of multiple ties in longitudinal egocentric network data: A case study on bidirectional relationships between trust and drug use.

We extend multi-level models to examine single egocentric network ties to the joint analysis of paired dynamic ties. Two analytic challenges are addressed. First, inference needs to account for multiple layers of nesting: ties are nested within pairs, pairs are nested within time points, and time points are nested within egos. Second, the focus is on the relationship between two dynamic ties; specification of outcome and predictor may be difficult. Instead, we treat both ties as outcomes. Our approach is used to analyze trust and reported drug use between egos and alters over time in a Bayesian framework.

Sexual networks, surveillance, and geographical space during syphilis outbreaks in rural North Carolina.

BACKGROUND: Sexually transmitted infections (STIs) spread along sexual networks whose structural characteristics promote transmission that routine surveillance may not capture. Cases who have partners from multiple localities may operate as spatial network bridges, thereby facilitating geographical dissemination. We investigated how surveillance, sexual networks, and spatial bridges relate to each other for syphilis outbreaks in rural counties of North Carolina. METHODS: We selected from the state health department's surveillance database cases diagnosed with primary, secondary, or early latent syphilis during October 1998 to December 2002 and who resided in central and southeastern North Carolina, along with their sex partners and their social contacts irrespective of infection status. We applied matching algorithms to eliminate duplicate names and create a unique roster of partnerships from which networks were compiled and graphed. Network members were differentiated by disease status and county of residence. RESULTS: In the county most affected by the outbreak, densely connected networks indicative of STI outbreaks were consistent with increased incidence and a large case load. In other counties, the case loads were low with fluctuating incidence, but network structures suggested the presence of outbreaks. In a county with stable, low incidence and a high number of cases, the networks were sparse and dendritic, indicative of endemic spread. Outbreak counties exhibited densely connected networks within well-defined geographic boundaries and low connectivity between counties; spatial bridges did not seem to facilitate transmission. CONCLUSIONS: Simple visualization of sexual networks can provide key information to identify communities most in need of resources for outbreak investigation and disease control.

Quantifying the Benefits of Link-Tracing Designs for Partnership Network Studies.

Difficult-to-reach populations are frequently sampled through various link-tracing based designs, which rely on interpersonal networks to identify members of the population. This article examines the substantive returns to one such multiple-link tracing design in the Colorado Springs "Project 90" HIV risk networks study. Cross-links were respondents who were targeted for enrollment because of being named as partners by at least two other respondents in the sample. We compare cross-links to other respondents on sociodemographic characteristics and network properties using bivariate and multivariate adjusted statistics. We evaluate their contributions to observed network structure by creating a set of counterfactual networks deleting the information they provided. Results suggest that the link-tracing techniques led to identifying populations that would have otherwise been missed and that their absence would have underestimated potential HIV risk by distorting epidemiologically relevant measures within the network.

Comparison of sexual mixing patterns for syphilis in endemic and outbreak settings.

BACKGROUND: In a largely rural region of North Carolina during 1998-2002, outbreaks of heterosexually transmitted syphilis occurred, tied to crack cocaine use and exchange of sex for drugs and money. Sexual partnership mixing patterns are an important characteristic of sexual networks that relate to transmission dynamics of sexually transmitted infections (STIs). METHODS: Using contact tracing data collected by disease intervention specialists, we estimated Newman assortativity coefficients and compared values in counties experiencing syphilis outbreaks to nonoutbreak counties, with respect to race/ethnicity, race/ethnicity and age, and the cases' number of social/sexual contacts, infected contacts, sex partners, and infected sex partners, and syphilis disease stage (primary, secondary, early latent). RESULTS: Individuals in the outbreak counties had more contacts and mixing by the number of sex partners was disassortative in outbreak counties and assortative nonoutbreak counties. Although mixing by syphilis disease stage was minimally assortative in outbreak counties, it was disassortative in nonoutbreak areas. Partnerships were relatively discordant by age, especially among older white men, who often chose considerably younger female partners. CONCLUSIONS: Whether assortative mixing exacerbates or attenuates the reach of STIs into different populations depends on the characteristic/attribute and epidemiologic phase. Examination of sexual partnership characteristics and mixing patterns offers insights into the growth of STI outbreaks that complement other research methods.

Sexual network structure among a household sample of urban african american adolescents in an endemic sexually transmitted infection setting.

BACKGROUND: Sexual networks play an important role in the transmission of sexually transmitted infections (STIs) and HIV. However, because of the challenges of collecting network data, relatively few empirical reports exist about the structure of sexual networks in general population samples. This study describes the structure of the sexual networks of a household sample of urban black adolescents living in an area with moderate endemic STI rates. METHODS: Random digit dialing was used to recruit a household sample of black adolescents from the Bayview-Hunter's Point neighborhood of San Francisco. Participants' recent partners and partners of partners were recruited through snowball sampling. Biologic samples were tested for current infection with gonorrhea or chlamydia. Social network analysis methods were used to describe the characteristics of the resulting sexual networks. RESULTS: One hundred and sixty-six sexually active participants were connected to 388 network members in 159 separate sexual network components. Despite relatively high prevalence of bacterial STIs (13%), components were small (3.5 people on average, and half involved only 2 people), linear and acyclic. Females were less central in their networks than males by local measures but just as central when overall structure was taken into account. CONCLUSIONS: Our results confirm, in a new setting, previous observations that sexual network structures necessary for endemic transmission of gonorrhea and chlamydia are sparsely connected.

Transmission network analysis in tuberculosis contact investigations.

BACKGROUND: Social network analysis (SNA) is an innovative approach to the collection and analysis of infectious disease transmission data. We studied whether this approach can detect patterns of Mycobacterium tuberculosis transmission and play a helpful role in the complex process of prioritizing tuberculosis (TB) contact investigations. METHODS: We abstracted routine demographic and clinical variables from patient medical records and contact interview forms. We also administered a structured questionnaire about places of social aggregation to TB patients and their contacts. All case-contact, contact-contact, case-place, and contact-place dyads (pairs and links) were considered in order to analyze the structure of a social network of TB transmission. Molecular genotyping was used to confirm SNA-detected clusters of TB. RESULTS: TB patients not linked through conventional contact-investigation data were connected through mutual contacts or places of social aggregation, using SNA methods. In some instances, SNA detected connected groups prior to the availability of genotyping results. A positive correlation between positive results of contacts' tuberculin skin test (TST) and location in denser portions of the person-place network was observed (P<.01). CONCLUSIONS: Correlation between TST-positive status and dense subgroup occurrence supports the value of collecting place data to help prioritize TB contact investigations. TB controllers should consider developing social network analysis capacity to facilitate the systematic collection, analysis, and interpretation of contact-investigation data.

The Atlanta Urban Adolescent Network Study: a network view of STD prevalence.

OBJECTIVES: To examine the epidemiology of multiple infections in teenagers and their contacts. GOAL: To demonstrate a network approach to the prevalence of STDs/HIV. STUDY DESIGN: A community-based network study of ethnographically representative adolescents. RESULTS: Of the 512 interviewees, 90% of the boys and 80% of the girls were sexually active with many partners and exhibited age-assortative mixing. Prevalences of gonorrhea, chlamydia, and HSV-2 were high, but syphilis, Hepatitis C and HIV were virtually absent. The prevalence faced by subgroups differed from overall prevalence. CONCLUSIONS: The presence of bacterial STDs and the absence of HIV, HCV, and syphilis may be the result of no IDU and assortative age mixing. Testing for multiple conditions, network assessment of prevalence, and inclusion of social contacts enhance understanding of STD epidemiology.

Large-network concepts and small-network characteristics: fixed and variable factors.

OBJECTIVES: To compare 15 completed network studies of STD/HIV transmission with regard to their structural characteristics. To determine similarities and differences in the network characteristics in different epidemiologic settings. STUDY DESIGN: Combined analysis of nearly 40,000 dyads, using epidemiologic and network analytic methods. RESULTS: In general, transmitting networks have a right-skewed degree distribution, a large single component, and small world characteristics. They vary with regard to concurrency, assortativity, and transitivity. CONCLUSIONS: The analysis suggests that networks in which transmission takes place have a common network infrastructure, but that the actual level of transmission may be determined by factors specific to a study population. Specific quantitation of the relationship between transmission and network characteristics will require an amalgam of empirical and theoretical methods.

Early syphilis among men in Connecticut: epidemiologic and spatial patterns.

OBJECTIVE: The objective of this study was to describe the epidemiology of early syphilis among men in Connecticut, a moderate-prevalence region, in 2004. STUDY DESIGN: The authors conducted a cross-sectional analysis of health department data. RESULTS: Fifty-five cases were reported from 25 different towns. A majority of cases (82%) were reported among men who have sex with men, and 22% reported coinfection with HIV. Spatial analysis indicated moderate clustering of cases. Approximately half of 197 reported sex partners were not from Connecticut, including 28% from New York City and 20% from other states/countries. The median distance between partners was 48 km (30 miles). Twenty-three percent of syphilis cases had both local and nonlocal partners. CONCLUSIONS: The current epidemiology of early syphilis in Connecticut is consistent with national trends. However, the dispersal of cases throughout the state and the high proportion of reported sex partners residing outside of Connecticut suggest that this state is not a core area of endemic transmission.

Factors and the sociosexual network associated with a syphilis outbreak in rural North Carolina.

OBJECTIVE: An investigation was conducted to determine factors associated with a syphilis outbreak in a rural North Carolina county. STUDY DESIGN: A retrospective chart review was performed on 61 primary (PS), secondary (SS), and early latent (ELS) syphilis case patients reported in Columbus County between January 2001 and February 2002. Sociosexual network analysis was conducted using electronic contact tracing information. RESULTS: We identified 20 PS, 25 SS, and 16 ELS case patients who were predominantly black. Seventy-two percent had reported >or=1 sexual partner with early syphilis, 51% used crack cocaine and/or had sex with a crack-using partner, and 31% exchanged sex for drugs or money. The sexual network exhibited predominantly linear connections between case patients and sexual partners. Adding social connections to the network further demonstrated dense cyclic interactions characteristic of core groups. CONCLUSIONS: The syphilis outbreak in this rural community was associated with crack cocaine and exchange of sex for drugs in a densely interconnected sociosexual network.