Parsing social network survey data from hidden populations using stochastic context-free grammars.

Background: Human populations are structured by social networks, in which individuals tend to form relationships based on shared attributes. Certain attributes that are ambiguous, stigmatized or illegal can create a OhiddenO population, so-called because its members are difficult to identify. Many hidden populations are also at an elevated risk of exposure to infectious diseases.

A tale of two cities: Social and environmental influences shaping risk factors and protective behaviors in two Mexico-US border cities.

The economic, social, cultural, and political milieus that influence HIV risk behaviors along the US-Mexico border are understudied. In an effort to appropriately inform interventions targeting structural influences, we compared injecting drug using populations living in two cities--Ciudad Juárez, Chihuahua and Tijuana, Baja California--situated on the Mexico-US border. These populations presented with similar demographic profiles, but differed significantly in terms of social and environmental influences that can influence both risk and protective factors (e.

Comparing heroin users and prescription opioid users in a Canadian multi-site population of illicit opioid users.

Introduction And Aims: Recent data suggest increasing prescription opioid and decreasing heroin use among street drug users, yet little is known on possible differential use characteristics and outcomes associated with these drugs. [While we recognise that, correctly, these populations would need to be labelled as opioid 'abusers' or 'non-medical users', we rely on the simpler terms 'use' and 'users' for the population under study within the wider context of them being engaged overall in illicit opioid use activities.] This study compared drug use, health, and socio-economic characteristics between heroin (H)-only, prescription opioid (PO)-only and mixed heroin and prescription (PO & H) users in a Canadian multi-site cohort of illicit opioid and other drug users (OPICAN).

Cross-border paid plasma donation among injection drug users in two Mexico-U.S. border cities.

Objective: Paid plasma donation has contributed to HIV epidemics in many countries. Eleven million liters of plasma are fractionated annually in the U.S.

Seroprevalence of select bloodborne pathogens and associated risk behaviors among injection drug users in the Paso del Norte region of the United States-Mexico border.

Background: The region situated where the borders of Mexico, Texas and New Mexico meet is known as 'Paso del Norte'. The Paso del Norte Collaborative was formed to study the seroprevalence of select pathogens and associated risk behaviors among injection drug users (IDUs) in the region.

Methods: Respondent-driven sampling (RDS) was used: 459 IDU participants included 204 from Mexico; 155 from Texas; and 100 from New Mexico.

Shooting gallery attendance among IDUs in Tijuana and Ciudad Juarez, Mexico: correlates, prevention opportunities, and the role of the environment.

We identified factors associated with shooting gallery attendance among injection drug users (IDUs) in two Mexico-US border cities. IDUs in Tijuana (n=222) and Ciudad Juarez (n=205), Mexico, who were >or=18 years and injected illicit drugs in the last month were recruited using respondent-driven sampling (RDS). An interviewer-administered survey collected sociodemographic and behavioral data.

Hepatitis C virus transmission among oral crack users: viral detection on crack paraphernalia.

Objective: Epidemiological studies present oral crack use as a potential independent risk factor for hepatitis C virus (HCV) status, yet actual HCV transmission pathways via crack use have not been evidenced. To this end, this exploratory study sought to detect HCV on crack-use paraphernalia used by street crack users.

Methods: Crack-use paraphernalia within 60 min of use was collected from 51 (N) street-crack users.

Barriers and missed opportunities to HIV testing among injection drug users in two Mexico--US border cities.

Introduction And Aims: Despite increasing HIV prevalence in cities along the Mexico--US border, HIV testing among high-risk populations remains low. We sought to identify barriers associated with HIV testing among injection drug users (IDUs) in Tijuana and Ciudad Juarez, the two largest Mexican border cities located across from San Diego, California and El Paso, Texas, respectively.

Design And Methods: In 2005, 222 IDUs in Tijuana and 205 IDUs in Ciudad Juarez were recruited by respondent-driven sampling and administered a questionnaire to collect socio-demographic, behavioural and HIV testing history data.

Public opinion towards supervised injection facilities and heroin-assisted treatment in Ontario, Canada.

In recent years, controversial interventions such as 'heroin-assisted treatment' (HAT) and 'supervised injection facilities' (SIFs) have been established in attempts to minimise the high morbidity and mortality consequences of illicit drug use. This paper examines public opinion towards HAT and SIF using data from the 2003 Centre for Addiction and Mental Health (CAMH) Monitor, a representative population survey conducted among adults residing in Ontario, Canada. Data relating specifically to SIFs and HAT were isolated from the main database (n=885); agreement scores were collapsed to create a scale and analysed using independent sample t-tests and ANOVAs.

Predictors of methadone maintenance treatment utilization in a multisite cohort of illicit opioid users (OPICAN).

Although methadone maintenance treatment (MMT) has been a primary treatment response to illicit opioid use in Canada for decades, analytical treatment data are scarce. Using data from the multisite OPICAN cohort of illicit opioid and other drug users repeatedly assessed between 2002 (baseline) and 2005 (last follow-up [FU]), we (1) longitudinally examined characteristics associated with MMT uptake between baseline and FU and (2) cross-sectionally compared drug use patterns between cohort participants in MMT (n = 133) and those not in MMT (n = 400) at the last FU through bivariate and multivariate analyses (stepwise logistic regression). Significant baseline predictors of MMT uptake emerging in the logistic regression model included injection drug, heroin, as well as alcohol use, housing status, and Quebec City as a site.

Prevalence of hepatitis C virus and HIV infection among injection drug users in two Mexican cities bordering the U.S.

Objective: To estimate the prevalence of the hepatitis C virus (HCV) and HIV infection and associated risk behaviors among injection drug users (IDUs) in two northern Mexican cities.

Material And Methods: Between February and April 2005, IDUs were recruited in Tijuana (N=222) and Ciudad Juarez (N=206) using respondent-driven sampling (RDS), a chain referral sampling approach. Interviewer-administered questionnaires assessed drug-using behaviors during the prior six months.

At the borders, on the edge: use of injected methamphetamine in Tijuana and Ciudad Juarez, Mexico.

Injection drug use is of increasing concern along the US-Mexico border where Tijuana and Ciudad (Cd.) Juarez are located. Methamphetamine has long been manufactured and trafficked through Mexico, with low rates of use within Mexico.

Prevalence and associated factors of hepatitis C infection (HCV) in a multi-site Canadian population of illicit opioid and other drug users (OPICAN).

Background: Hepatitis C virus (HCV) infection is highly prevalent in illicit drug user populations, with three in four new HCV infections related to this risk behaviour and a growing HCV disease burden in Canada. Using data from a multi-site cohort study of illicit opioid users in five Canadian cities (OPICAN), this paper explores the prevalence and predictors of HCV status in this high-risk population.

Methods: HCV status of cohort participants was assessed by salivary antibody test.

Respondent-driven sampling of injection drug users in two U.S.-Mexico border cities: recruitment dynamics and impact on estimates of HIV and syphilis prevalence.

Respondent-driven sampling (RDS), a chain referral sampling approach, is increasingly used to recruit participants from hard-to-reach populations, such as injection drug users (IDUs). Using RDS, we recruited IDUs in Tijuana and Ciudad (Cd.) Juárez, two Mexican cities bordering San Diego, CA and El Paso, TX, respectively, and compared recruitment dynamics, reported network size, and estimates of HIV and syphilis prevalence.

Illicit opioid use and its key characteristics: a select overview and evidence from a Canadian multisite cohort of illicit opioid users (OPICAN).

Objectives: To summarize key characteristics and consequences of illicit opioid use from the literature and to present corresponding data from a multisite sample of illicit opioid users in 5 Canadian cities (OPICAN study).

Method: We undertook an overview of recent literature from North America, Australia, and Europe. We obtained data from the multicity OPICAN cohort study, which consisted of an interviewer-administered questionnaire, a standardized mental health instrument (the Composite International Diagnostic Interview Short Form for depression), and saliva-antibody tests for infectious disease (that is, HIV and hepatitis C virus).

A qualitative exploration of gender in the context of injection drug use in two US-Mexico border cities.

Injection drug use is of increasing concern along the U.S.-Mexico border where Tijuana and Ciudad (Cd.