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HIV transmission in Ukraine is driven in part by unsafe injection drug use and sexual risk behaviors among people who inject drugs. We performed a random-intercept latent transition analysis on responses to 9 binary injection drug use and sexual behavior items from 1195 people who inject drugs with negative HIV status enrolled in a clustered randomized clinical trial of a social network intervention in Odessa, Donetsk, and Nikolayev, Ukraine. We identified 5 baseline classes: "Social injection/equipment-sharing" (11.7%), "Social injection" (25.9%), "High-risk collective preparation/splitting" (17.0%), "Collective preparation/splitting" (11.3%), and "Dealer-facilitated injection" (34.1%). After 12 months, intervention participants were more likely to transition to the "Collective preparation/splitting" class, which featured the fewest risk behaviors. Transitioning from the "Collective preparation/splitting" to the "Social injection/equipment-sharing" class was associated with HIV acquisition for control participants. Research to illuminate the stability of these patterns and how they may benefit from uniquely tailored programming to reduce unsafe behaviors is needed.

Food insecurity (FI) impacts people with HIV (PWH) and those who use substances (i.e. drugs and alcohol). We evaluated the longitudinal association between FI and HIV transmission risks (unprotected sexual contacts and shared needles/syringes). Among 351 PWH who use substances in Russia, 51.6% reported FI and 37.0% past month injection drug use. The mean number of unprotected sexual contacts in the past 90 days was 13.4 (SD 30.1); 9.7% reported sharing needles/syringes in the past month. We did not find a significant association between mild/moderate FI (adjusted IRR = 0.87, 95% CI 0.47, 1.61) or severe FI (aIRR = 0.84, 95% CI 0.46, 1.54; global p = 0.85) and unprotected sexual contacts. We observed a significant association between severe FI and sharing needles/syringes in the past month (adjusted OR = 3.27, 95% CI 1.45, 7.39; p = 0.004), but not between mild/moderate FI and sharing needles/syringes in the past month (aOR = 1.40,95% CI 0.58, 3.38; p = 0.45). These findings suggest that severe FI could be a potential target for interventions to lower HIV transmission.

People with HIV (PWH) who inject drugs often experience coexisting HIV- and substance use-related stigma manifestations. We assessed correlates of HIV stigma (Berger HIV stigma scale), substance use stigma (Substance Abuse Self-stigma scale) and intersectional HIV and substance use stigma in a cohort of PWH with a lifetime history of drug use in St. Petersburg, Russia. Intersectional stigma was defined as having a score greater than the median for both forms of stigma. Of the 208 participants, 56 (27%) had intersectional stigma. Depressive symptoms and alcohol dependence were significantly associated with a higher HIV and substance stigma score, but not with intersectional stigma. Individual and community interventions to reduce the impact of HIV stigma and substance use stigma affecting PWH who inject drugs should consider assessing and addressing mental health and unhealthy substance use. Further work with longitudinal data is needed to understand mechanisms leading to intersectional stigma.

The COVID-19 related U.S.-Mexico border-crossing restrictions disrupted social networks and HIV harm reduction services among people who inject drugs (PWID) in San Diego and Tijuana. We assessed associations of descriptive network norms on PWID's HIV vulnerability during this period. Between 10/2020 and 10/2021, 399 PWID completed a behavioral and egocentric questionnaire. We used Latent Profile Analysis to categorize PWID into network norm risk profiles based on proportions of their network (n = 924 drug use alters) who injected drugs and engaged in cross-border drug use (CBDU), among other vulnerabilities. We used logistic and linear regressions to assess network profile associations with individual-level index of HIV vulnerability and harm reduction behaviors. Fit indices specified a 4-latent profile solution of descriptive network risk norms: lower (n = 178), moderate with (n = 34) and without (n = 94) CBDU and obtainment, and higher (n = 93). Participants in higher risk profiles reported more HIV vulnerability behaviors and fewer harm reduction behaviors. PWID's gradient of HIV risk was associated with network norms, warranting intervention on high-vulnerability networks when services are limited.

This study evaluated the association between impulsivity and linkage to HIV care among Russians living with HIV recruited from an inpatient narcology hospital. Linking Infectious and Narcology Care (LINC) study participants who completed the Barratt Impulsiveness Scale (BIS) were included in these analyses. The primary independent variable was impulsivity score which was categorized as high impulsivity (BIS score > 71) vs. low impulsivity (BIS score

Tijuana, Mexico, has a concentrated HIV epidemic among overlapping key populations (KPs) including people who inject drugs (PWID), female sex workers (FSW), their male clients, and men who have sex with men (MSM). We developed a dynamic HIV transmission model among these KPs to determine the extent to which their unmet prevention and treatment needs is driving HIV transmission. Over 2020-2029 we estimated the proportion of new infections acquired in each KP, and the proportion due to their unprotected risk behaviours. We estimate that 43.7% and 55.3% of new infections are among MSM and PWID, respectively, with FSW and their clients making-up

Little is known about the intersection of HIV stigma and substance use stigma. Using data from 188 HIV-positive people who inject drugs (PWID) in Russia, we examined the associations of these stigmas and their interaction with access and utilization of healthcare. While substance use stigma was significantly associated with poor access to care (AOR 2.31, 95%CI 1.50-3.57), HIV stigma was not. HIV stigma was associated with lower inpatient care utilization (AOR 0.32, 95%CI 0.14-0.65), while substance use stigma was not. We did not detect a significant interaction between the two forms of stigma for either of the primary outcomes. However, those with high levels of both substance use stigma and HIV stigma had higher odds of poor general access to healthcare (AOR 1.86, 95%CI 1.19-2.92), and lower odds of recent general outpatient (AOR 0.52, 95%CI 0.32-0.85) and any inpatient (AOR 0.48, 95%CI 0.22-0.99) care utilization compared to those with low levels of both types of stigma. Interventions addressing both substance use and HIV stigma in general healthcare settings might improve care in this HIV key population.

Coronavirus Disease 2019 (COVID-19) may influence HIV/HCV transmission risk behaviors in rural communities. We conducted semi-structured qualitative interviews with people who use drugs (PWUD) in five rural Oregon counties and asked about COVID-19 impact on substance use and harm reduction practices and their advice for improving public health responses. Participants (n = 36) reported using only methamphetamine (52.8%), only heroin (16.7%), or both (30.6%); 75% of participants reported recent injection. Three thematic categories emerged: SSP adaptations and accessibility, PWUD harm reduction practices, and policy suggestions. Participants noted the importance of SSPs to COVID-19 prevention and wellbeing, though some experienced increased barriers, leading to increased risky injection practices. Participants suggested need-based rather than one-for-one exchange, increasing syringe delivery services, encouraging secondary exchange by PWUD, and peers as trusted voices for information exchange. Rapid implementation of policy and practice changes are urgently required to improve SSP access, reinforce safer use, and prevent HIV/HCV and COVID-19 transmission.

We studied mechanisms driving gender differences in HIV incidence among 651 women and men who inject drugs (PWID) in Tijuana, Mexico, hypothesizing that sex work will mediate the association between female gender and HIV incidence. Of 43 HIV seroconversions occurring between 2011 and 2018, 8.8% were among females and 5.2% among males. HIV incidence density was significantly higher among females versus males (1.75 per 100 person years [PY], 95% CI 1.16-2.66, vs. 0.95 per 100 PY, 95% CI 0.62-1.47). Factors significantly associated with HIV seroconversion were: sex work (adjusted hazard ratio [aHR] = 2.25, 95% CI 1.05-4.80); methamphetamine injection (aHR = 2.30, 95% CI 1.12-4.73); and methamphetamine and heroin co-injection in the past six months (aHR = 2.26, 95% CI 1.23-4.15). In mediation analyses, sex work mediated a substantial proportion (84.3%) of the association between female gender and HIV incidence. Interventions should target female PWID who engage in sex work to reduce gender-related disparities in HIV incidence.

We used two national surveys (2010: N = 1597; 2013: N = 1057) of people who inject drugs (PWID) in past-month to assess the prevalence and population size of PWID with either safe or unsafe injection and sex behaviors, overall and by HIV status. In 2013, only 27.0% (vs. 32.3% in 2010) had safe injection and sex, 24.6% (vs. 23.3% in 2010) had unsafe injection and sex, 26.4% (vs. 26.5% in 2010) had only unsafe injection, and 22.0% (vs. 18.0% in 2010) had unsafe sex only. Among HIV-positive PWID in 2013, only 22.1% (~ 2200 persons) had safe injection and sex, 14.2% (~ 1400 persons) had unsafe injection and sex, 53.1% (~ 5200 persons) had unsafe injection, and 10.6% had unsafe sex (~ 1100 persons). Among HIV-negative PWID in 2013, only 27.5% (~ 22,200 persons) had safe injection and sex, 25.9% (~ 20,900 PWID) had unsafe injection and sex, 23.2% (~ 18,700 persons) had unsafe injection, and 23.3% (~ 18,800 persons) had unsafe sex. HIV-positive and -negative PWID in Iran continue to be at risk of HIV acquisition or transmission which calls for targeted preventions services.

For individuals living with human immunodeficiency virus (HIV), viral suppression positively affects quality and length of life and reduces risks for HIV transmission. Men of color who have sex with men (MoCSM) who have been diagnosed with HIV have disproportionately low rates of viral suppression, with concomitant increases in incidence. We identified specific social, structural, and psychiatric factors associated with viral suppression among a sample of 155 HIV-positive MoCSM. Cigarette smoking and biological markers of recent drug use were significantly associated with detectable viral load. In contrast, individuals reporting a history of psychiatric illness during medical examination were more likely to be virally suppressed. Further analyses demonstrated that psychiatric illness may affect virologic outcomes through increased probability of being prescribed HIV medications. Alternatively, cigarette smoking and drug use appear to negatively affect subsequent HIV Care Continuum milestones such as medication adherence. Findings provide support for comprehensive intervention programs that emphasize prevention and treatment of cigarette, methamphetamine, and other drug use, and promote improved connection to psychiatric care. Continual achievement of this goal may be a crucial step to increase rates of viral suppression and slow HIV incidence in communities of MoCSM in Los Angeles and other urban areas.

Among persons who inject drugs, women have a higher HIV prevalence (than men) in many settings. Understanding how gender affects risk for infection among HIV-negative, and transmission among HIV-positive people who currently or previously injected drugs is key to designing effective prevention and treatment programs. We analyzed data from 291 persons living with HIV who had ever injected drugs. Participants were drawn from the Russia Alcohol Research Collaboration on HIV/AIDS cohort (2012-2015) to examine associations between female gender and HIV transmission risk. Primary outcomes were sharing drug injecting equipment (e.g., needle/syringes) and condomless sex. Secondary outcomes were alcohol use before sharing drug injecting equipment; before condomless sex; and both sharing drug injecting equipment and condomless sex. Logistic regression models assessed associations between gender and outcomes, controlling for demographics, partner HIV status and use of antiretroviral treatment. Female gender was not significantly associated with sharing drug injecting equipment [aOR = 1.45, 95% confidence interval (CI) 0.85-2.46, p value = 0.18] but was associated with condomless sex (aOR = 1.91, 95% CI 1.12-3.23, p = 0.02) in adjusted models. Female gender was not significantly associated with any secondary outcomes. Better understanding of risky sex and drug use behaviors among people who currently or previously injected drugs can support the design of effective gender-tailored HIV prevention interventions.

Since the discovery of the secondary preventive benefits of antiretroviral therapy, national and international governing bodies have called for countries to reach 90% diagnosis, ART engagement and viral suppression among people living with HIV/AIDS. The US HIV epidemic is dispersed primarily across large urban centers, each with different underlying epidemiological and structural features. We selected six US cities, including Atlanta, Baltimore, Los Angeles, Miami, New York, and Seattle, with the objective of demonstrating the breadth of epidemiological and structural differences affecting the HIV/AIDS response across the US. We synthesized current and publicly-available surveillance, legal statutes, entitlement and discretionary funding, and service location data for each city. The vast differences we observed in each domain reinforce disparities in access to HIV treatment and prevention, and necessitate targeted, localized strategies to optimize the limited resources available for each city's HIV/AIDS response.

We mapped hot spots and estimated the numbers of people who use drugs (PWUD) and who inject drugs (PWID) in 12 regions of Tanzania. Primary (ie, current and past PWUD) and secondary (eg, police, service providers) key informants identified potential hot spots, which we visited to verify and count the number of PWUD and PWID present. Adjustments to counts and extrapolation to regional estimates were done by local experts through iterative rounds of discussion. Drug use, specifically cocaine and heroin, occurred in all regions. Tanga had the largest numbers of PWUD and PWID (5190 and 540, respectively), followed by Mwanza (3300 and 300, respectively). Findings highlight the need to strengthen awareness of drug use and develop prevention and harm reduction programs with broader reach in Tanzania. This exercise provides a foundation for understanding the extent and locations of drug use, a baseline for future size estimations, and a sampling frame for future research.

We examined the association of dyadic-level factors with syringe sharing among people who inject drugs (PWID) in Kerman, Iran. In a cross-sectional study, we collected data on 329 drug-injecting dyads by individual face-to-face interviews. An injecting dyad was defined as 2 PWID who knew each other and injected drugs together during the last 6 months. If they reported at least 1 occasion of syringe sharing, the dyad was considered high-risk. Dyadic-level factors associated with syringe sharing were assessed using cross-classified multilevel logistic regression. The rate of syringe sharing was significantly higher for dyads who were more intimate (adjusted odds ratio [AOR] 4.5, CI 95%, 2.3-8.6), who had instrumental support (AOR 2.1, 95% CI 1.1-4.5), and who pooled money for drugs (AOR 4.1, 95% CI 2.0-8.3). The rate was lower in same-sex dyads (AOR 0.4, 95% CI 0.2-0.9) and in dyads who shared health information (AOR 0.5, 95% CI 0.2-0.9). Findings highlight close-peer influences on syringe-sharing behavior.

HIV-infected individuals "aware" of their infection are more likely to use condoms, compared to HIV-infected "unaware" persons. To quantify this likelihood, we undertook a systematic review and meta-analysis of U.S. and Canadian studies. Twenty-one eligible studies included men who have sex with men (MSM; k = 15), persons who inject drugs (PWID; k = 2), and mixed populations of high-risk heterosexuals (HRH; k = 4). Risk ratios (RR) of "not always using condoms" with partners of any serostatus were lower among aware MSM (RR 0.44 [not significant]), PWID (RR 0.70) and HRH (RR 0.27); and, in aware MSM, with partners of HIV-uninfected or unknown status (RR 0.46). Aware individuals had lower "condomless sex likelihood" with HIV-uninfected or unknown status partners (MSM: RR 0.58; male PWID: RR 0.44; female PWID: RR 0.65; HRH: RR 0.35) and with partners of any serostatus (MSM only, RR 0.72). The association diminished over time. High risk of bias compromised evidence quality.

Despite the high incidence of HIV among young Black MSM in the United States and engagement in high risk behaviors, many men in this group avoid infection. This suggests that some men may engage in systematic risk reduction behaviors when not always using condoms or abstaining from substances. Using a "positive deviance" framework, we conducted qualitative interviews with HIV-negative, Black MSM between 25 and 35 who reported unprotected anal sex and drug use in the past six months or current heavy drinking (N = 29) to discover behaviors that could facilitate remaining HIV-uninfected. Findings showed that MSM who remain HIV negative despite continuing to engage in high-risk behaviors may be engaging in adaptive risk reduction behaviors that, through successive decisions and advance planning along the timeline to a sexual event, could lead to increased condom use, avoidance or delay of a risky sexual event, or reduction of HIV positive partners.

We measured HIV incidence rate, trend and risk factors in 564 HIV-negative young people (

Alcohol use can limit the effectiveness of antiretroviral therapy (ART) for people living with HIV (PLH) who have a history of injecting drug use. This study described the patterns of alcohol use among PLH with a history of injecting drug use in Vietnam and examined the relationships between alcohol use, adherence to ART, and sexual risks. We utilized cross-sectional data of 109 PLH on ART collected from a randomized controlled intervention trial in Vietnam. Approximately 30 and 46% of the participants were frequent and occasional drinkers, respectively. Frequent drinkers reported the highest number of missed medication days. About 61% of frequent drinkers reported having sex after using alcohol. Additionally, 23, 34, and 24% of nondrinkers, occasional drinkers, and frequent drinkers, respectively, reported inconsistent condom use during sex. Future intervention programs should address the issues of alcohol use and sexual risks to maximize the effectiveness of HIV treatment programs in Vietnam.

In HIV-infected drinkers, alcohol types more likely to cause inflammation could plausibly increase the risk of HIV disease progression. We therefore assessed the association between alcohol type and plasma HIV RNA level (HIV viral load) among HIV-infected drinkers not on antiretroviral therapy (ART) in Russia and Uganda. We analyzed the data of participants from cohorts in Russia and Uganda and assessed their HIV viral load at enrollment by the alcohol type predominantly consumed. We defined predominant alcohol type as the alcohol type contributing >50% of total alcohol consumption in the 1 month (Russia) or 3 months (Uganda) prior to enrollment. Using multiple linear regression, we compared log10 HIV viral load by predominant alcohol type, controlling for age, gender, socioeconomic status, total number of standard drinks, frequency of drinking ≥6 drinks/occasion, and in Russia, history of injection drug use. Most participants (99.2% of 261 in Russia and 98.9% of 352 in Uganda) predominantly drank one alcohol type. In Russia, we did not find evidence for differences in viral load levels between drinkers of fortified wine (n = 5) or hard liquor (n = 49), compared to drinkers of beer/low-ethanol-content cocktails (n = 163); however, wine/high-ethanol-content cocktail drinkers (n = 42) had higher mean log10 viral load than beer/low-ethanol-content cocktail drinkers (β = 0.38, 95% CI 0.07-0.69; p = 0.02). In Uganda, we did not find evidence for differences in viral load levels between drinkers of locally-brewed beer (n = 41), commercially-distilled spirits (n = 38), or locally-distilled spirits (n = 43), compared to drinkers of commercially-made beer (n = 218); however, wine drinkers (n = 8) had lower mean log10 HIV viral load (β = -0.65, 95% CI -1.36 to 0.07, p = 0.08), although this did not reach statistical significance. Among HIV-infected drinkers not yet on ART in Russia and Uganda, we observed an association between the alcohol type predominantly consumed and the HIV viral load level in the Russia sample. These exploratory results suggest that, in addition to total number of drinks and drinking patterns, alcohol type might be a dimension of alcohol use that merits examination in studies of HIV and alcohol related outcomes.

Food insecurity (FI) is a documented problem associated with adverse health outcomes among HIV-infected populations. Little is known about the relationship between alcohol use and FI. We assessed whether heavy alcohol use was associated with FI among HIV-infected, antiretroviral therapy (ART)-naïve cohorts in Uganda and Russia. Inverse probability of treatment weighted logistic regression models were used to evaluate the association using cross-sectional baseline data. FI was experienced by half of the Russia cohort (52 %) and by a large majority of the Uganda cohort (84 %). We did not detect an association between heavy alcohol use and FI in either cohort (Russia: AOR = 0.80, 95 % CI 0.46, 1.40; Uganda: AOR = 1.00, 95 % CI 0.57, 1.74) or based on the overall combined estimate (AOR = 0.89, 95 % CI 0.60, 1.33). Future studies should explore the determinants of FI in HIV-infected populations to inform strategies for its mitigation.

A total of 2768 MSM participated in a survey in southern Vietnam. Univariate and multivariate logistic regression analyses were performed to determine predictors of HIV infection. The prevalence of HIV among MSM was 2.6 %. HIV infection was more likely in MSM who were older, had a religion, had engaged in anal sex with a foreigner in the past 12 months, previously or currently used recreational drugs, perceived themselves as likely or very likely to be infected with HIV, and/or were syphilis seropositive. MSM who had ever married, were exclusively or frequently receptive, sometimes consumed alcohol before sex, and/or frequently used condoms during anal sex in the past 3 months were less likely to be infected with HIV. Recreational drug use is strongly associated with HIV infection among MSM in southern Vietnam. HIV interventions among MSM should incorporate health promotion, condom promotion, harm reduction, sexually transmitted infection treatment, and address risk behaviors.

In Tijuana, Mexico, HIV is concentrated in sub-epidemics of key populations: persons who inject drugs (PWID), sex workers (SW), and men who have sex with men (MSM). To date, data on engagement in the HIV care continuum among these key populations, particularly in resource-constrained settings, are sparse. We pooled available epidemiological data from six studies (N = 3368) to examine HIV testing and treatment uptake in these key populations; finding an overall HIV prevalence of 5.7 %. Of the 191 identified HIV-positive persons, only 11.5 % knew their HIV-positive status and 3.7 % were on ART. Observed differences between these HIV-positive key populations suggest PWID (vs. non-PWID) were least likely to have previously tested or initiate HIV care. MSM (vs. non-MSM) were more likely to have previously tested but not more likely to know their HIV-positive status. Of persons aware of their HIV-positive status, SW (vs. non-SW) were more likely to initiate HIV care. Findings suggest engagement of key populations in HIV treatment is far below estimates observed for similarly resource-constrained generalized epidemics in sub-Saharan Africa. These data provide one of the first empirical-snapshots highlighting the extent of HIV treatment disparities in key populations.

Injection drug-using men from the US and Mexico who purchase sex in Tijuana, Mexico are at risk for transmitting HIV to their contacts in both countries via syringe sharing. We used social network methods to understand whether place of residence (US vs. Mexico) moderated the effect of emotional closeness on syringe sharing. We interviewed 199 drug-using men who reported paying/trading for sex in Tijuana, Mexico using an epidemiological and social network survey and collected samples for HIV/STI testing. Seventy-two men reported using injection drugs with 272 network contacts. Emotional closeness was strongly associated with syringe sharing in relationship where the partner lives in the US, while the relationship between emotional closeness and syringe sharing was considerably less strong in dyads where the partner lives in Mexico. Efforts to reduce HIV risk behaviors in emotionally close relationships are needed, and could benefit from tailoring to the environmental context of the relationship.

The need to achieve ≥95 % adherence to HAART for treatment effectiveness may be a barrier for universal initiation at early stages of HIV. Using longitudinal data collected from 2006 to 2011 from cohort studies of MSM (MACS) and IDUs (ALIVE study), we estimated the minimum adherence needed to achieve HIV RNA suppression (

Unsafe injection practices significantly increase the risk of hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection among injection drug users (IDUs). We examined individual and socio-environmental factors associated with unsafe injection practices in young adult IDUs in San Diego, California. Of 494 IDUs, 46.9 % reported receptive syringe sharing and 68.8 % sharing drug preparation paraphernalia in the last 3 months. Unsafe injection practices were associated with increased odds of having friends who injected drugs with used syringes, injecting with friends or sexual partners, and injecting heroin. Perceived high susceptibility to HIV and perceived barriers to obtaining sterile syringes were associated with increased odds of receptive syringe sharing, but not with sharing injection paraphernalia. Over half the IDUs reported unsafe injection practices. Our results suggest that personal relationships might influence IDUs' perceptions that dictate behavior. Integrated interventions addressing individual and socio-environmental factors are needed to promote safe injection practices in this population.

A significant body of research among female sex workers (FSWs) has focused on individual-level HIV risk factors. Comparatively little is known about their non-commercial, steady partners who may heavily influence their behavior and HIV risk. This cross-sectional study of 214 FSWs who use drugs and their male steady partners aged ≥18 in two Mexico-U.S. border cities utilized a path-analytic model for dyadic data based upon the Actor-Partner Interdependence Model to examine relationships between sexual relationship power, intimate partner violence (IPV), depression symptoms, and unprotected sex. FSWs' relationship power, IPV perpetration and victimization were significantly associated with unprotected sex within the relationship. Male partners' depression symptoms were significantly associated with unprotected sex within the relationship. Future HIV prevention interventions for FSWs and their male partners should address issues of sexual relationship power, IPV, and mental health both individually and in the context of their relationship.

Respondent-driven sampling's (RDS) widespread use and reliance on untested assumptions suggests a need for new exploratory/diagnostic tests. We assessed geographic recruitment bias and outcome-correlated recruitment among 1,048 RDS-recruited people who inject drugs (Tijuana, Mexico). Surveys gathered demographics, drug/sex behaviors, activity locations, and recruiter-recruit pairs. Simulations assessed geographic and network clustering of active syphilis (RPR titers ≥1:8). Gender-specific predicted probabilities were estimated using logistic regression with GEE and robust standard errors. Active syphilis prevalence was 7 % (crude: men = 5.7 % and women = 16.6 %; RDS-adjusted: men = 6.7 % and women = 7.6 %). Syphilis clustered in the Zona Norte, a neighborhood known for drug and sex markets. Network simulations revealed geographic recruitment bias and non-random recruitment by syphilis status. Gender-specific prevalence estimates accounting for clustering were highest among those living/working/injecting/buying drugs in the Zona Norte and directly/indirectly connected to syphilis cases (men: 15.9 %, women: 25.6 %) and lowest among those with neither exposure (men: 3.0 %, women: 6.1 %). Future RDS analyses should assess/account for network and spatial dependencies.

We analyzed data from a large randomized HIV/HCV prevention intervention trial with young injection drug users (IDUs). Using categorical latent variable analysis, we identified distinct classes of sexual behavior for men and women. We conducted a latent transition analysis to test the effect of the intervention on transitions from higher to lower risk classes. Men who were in a high-risk class at baseline who received the intervention were 86 % more likely to be in a low-risk class at follow-up compared to those in the control group (p = 0.025). High-risk intervention participants were significantly more likely to transition to the class characterized by unprotected sex with a main partner only, while low-risk intervention participants were significantly less likely to transition to that class. No intervention effect was detected on the sexual risk behavior of women, or of men who at baseline were having unprotected sex with a main partner only.

Injection drug users (IDU) who use methamphetamine (MA) are at an increased risk of HIV infection due to engagement in injection-related risk behavior including syringe sharing. In this cohort study of young IDU aged 18-30, we investigated the relationship between injection MA use and syringe sharing, and whether difficulty accessing sterile syringes mediated this association. Behavioral questionnaires were completed by 384 IDU in Vancouver, Canada between October 2005 and May 2008. Generalized estimating equations were used to estimate direct and indirect effects. The median age of participants was 24 (IQR: 22-27) and 214 (55.7%) were male. Injecting MA was independently associated with syringe sharing. Mediation analyses revealed that difficulty accessing sterile syringes partially mediated the association between injecting MA and syringe sharing. Interventions to reduce syringe sharing among young methamphetamine injectors must address social and structural barriers to accessing HIV prevention programs.

We examined the effect of women's perceptions of sexual partner risks on condom use. Women from three US cities (n = 1,967) were recruited to provide data on HIV risks. In univariate models, increased odds of condom use were associated with perceiving that partners had concurrent partners and being unaware of partners': (a) HIV status, (b) bisexuality, (c) concurrency; and/or (d) injection drug use. In multivariate models, neither being unaware of the four partner risk factors nor perceiving a partner as being high risk was associated with condom use. Contextual factors associated with decreased odds of condom use were having sex with a main partner, homelessness in the past year, alcohol use during sex, and crack use in the past 30 days. Awareness of a partner's risks may not be sufficient for increasing condom use. Contextual factors, sex with a main partner in particular, decrease condom use despite awareness of partner risk factors.

We investigated the longitudinal influence of individual-, relationship- and social-level factors on condom use by partner type among young injections drug users (IDUs) enrolled in the Collaborative Injection Drug Users Study-III/Drug Users Intervention Trial (CIDUS-III/DUIT) from 2002 to 2004. Based on longitudinal analysis using generalized estimating equations (GEE), consistent condom use with main partners was more commonly reported among males and those with greater self-efficacy for condom use; main partner's desire for pregnancy and needle sharing were negatively associated with consistent condom use. Among those with casual partners, having fewer sex partners was associated with consistent condom use. Positive attitudes toward condom use and partner norms supporting condom use were associated with greater consistent condom use with both partner types. These findings suggest that intervention strategies targeting individual- and partner-level factors may provide avenues for intervening upon sexual risks among young IDUs.

We examined relationships between client-perpetrated emotional, physical, and sexual abuse, injection drug use, and HIV-serostatus among 924 female sex workers (FSWs) in Tijuana and Ciudad Juarez, two large Mexico-US border cities. We hypothesized that FSWs' injection drug use would mediate the relationship between client-perpetrated abuse and HIV-seropositivity. The prevalence of client-perpetrated emotional, physical, and sexual abuse in the past 6 months was 26, 18, and 10% respectively; prevalence of current injection drug use and HIV was 12 and 6%, respectively. Logistic regression analyses revealed that client-perpetrated sexual abuse was significantly associated with HIV-seropositivity and injection drug use, and that injection drug use was positively associated with HIV-seropositivity. Injection drug use partially mediated the relationship between client-perpetrated sexual abuse and HIV-seropositivity. Results suggest the need to address client-perpetrated violence and injection drug use when assessing HIV risk among FSWs.