Rethinking approaches to risk reduction for injection drug users: differences in drug type affect risk for HIV and hepatitis C virus infection through drug-injecting networks

OBJECTIVE: To identify and compare the drug-injecting network characteristics of cocaine and heroin injectors associated with a risk of HIV and hepatitis C virus (HCV). METHODS: Active injectors were recruited from syringe exchange and methadone programs. Characteristics of all participants and their social networks were elicited. Regression analysis using generalized estimating equations examined the network characteristics of injection drug users (IDUs) relative to cocaine or heroin use in the past 6 months. RESULTS: Of 282 IDUs, 228 (81%) used cocaine and 54 (19%) used heroin as their primary injected drug. In analyses adjusted for age and gender, cocaine injectors compared with heroin injectors were more likely to live in unstable housing (odds ratio [OR] = 3.55, 95% confidence interval [CI]: 1.49 to 8.40), self-report HCV infection (OR = 4.69, 95% CI: 2.14 to 10.31), and have a greater number of IDUs in their social network (OR = 1.61, 95% CI: 1.14 to 2.28) and were less likely to be polydrug users (OR = 0.06, 95% CI: 0.02 to 0.16) and to have social support (OR = 0.97, 95% CI: 0.95 to 0.99). The injecting networks of cocaine users were more likely to have members who were older (OR = 1.08, 95% CI: 1.04 to 1.12), had a history of shooting gallery use (OR = 2.27, 95% CI: 1.08 to 4.76), and had shorter relationships with the subject (OR = 0.91, 95% CI: 0.85 to 0.97). CONCLUSIONS: Beyond personal behaviors, HIV and HCV infection risk seems to be linked to social network traits that are determined by drug type. Prevention efforts to control the spread of bloodborne viruses among IDUs could benefit from tailoring interventions according to the type of drug used.     

The HCV Synthesis Project: Scope,methodology, and preliminary results

Background  

The hepatitis C virus (HCV) is hyper-endemic in injecting drug users. There is also excess HCV among non-injection drug users who smoke, snort, or sniff heroin, cocaine, crack, or methamphetamine.     

Risk correlates of prevalent HIV,hepatitis B virus,and hepatitis C virus infections among noninjecting heroin users

OBJECTIVE: To examine lifetime correlates of HIV and hepatitis B and C (HBV and HCV) infections among noninjecting heroin users (NIUs). METHODS: Between March 1996 and March 2001, 483 eligible NIUs were tested for HIV, HBV, and HCV antibodies and administered structured interviews. Multivariate logistic regression analyses were stratified by injecting history. RESULTS: Among never-injectors (69.8%), significant (p <.05) correlates were unprotected sex with men who have sex with men (HIV and HBV), unprotected sex with NIUs (HIV), self-reported syphilis infection (HBV), longer duration of heroin use (HBV and HCV), shorter duration of cocaine use (HIV), blood transfusion before 1986 (HIV), and having been tattooed (HCV). Among former injectors (30.2%), significant correlates were receptive syringe sharing (HIV and HBV), frequent lifetime injection (HCV), longer duration of sexual activity (HBV), and having been tattooed (HCV). CONCLUSION: Never-injectors infected with HIV and HBV appear to have become infected mainly through sexual transmission, whereas former injectors appear to have become infected with HIV and HCV mainly though injecting risk and with HBV through both injecting and sexual risk. Interventions targeted at NIUs should prevent unsafe sex as well as the initiation or resumption of injecting. In addition, unhygienic tattooing, which may lead to HCV exposure, should be a focus of prevention efforts.     

Experience of hepatitis C among current or former heroin users attending general practice

The majority of injecting drug users in Ireland are infected with hepatitis C (HCV) and many attend general practice for methadone maintenance treatment. To describe awareness and experience of HCV infection, related investigations and treatment, a semi-qualitative interview study of current or former heroin users attending a general practice was carried out. Twenty-five patients (69% of total) were interviewed, of whom 23 were on methadone maintenance therapy at the time of the interview and 22 were HCV positive. While awareness of harm reduction measures and health implications of the infection was good, continued high-risk activity was common. Negative experiences at diagnosis, of subsequent investigations and treatments received were common. Only one person had been treated for HCV. We conclude there are a number of barriers to effective HCV management among heroin users and further research is needed to improve our understanding of this issue.     

Hepatitis C virus among self declared non-injecting sexual partners of injecting drug users

While much is known about hepatitis C virus (HCV) among injecting drug users (IDUs), there is scant information about the risk of HCV infection to non-injecting sexual partners of injecting drug users; it is possible that such individuals may have a greater risk of acquiring HCV than any other group barring injecting drug users. This study examines the prevalence of HCV among a population of non-injecting sexual partners of injecting drug users. Unlinked anonymous testing for anti-HCV of residual sera stored following the named HIV testing of specimens originally from persons who had indicated to their attending clinicians that they were non-injecting sexual partners of injecting drug users. The prevalence of anti-HCV among the sexual partners was 4.1% (25/611) overall, 6.4% (13/202) among heterosexual male and 3.0% (12/397) among the heterosexual female partners. None of the homosexual/bisexual partners were HCV antibody positive (0/12). Although we cannot be sure how non-injecting partners of injecting drug users acquire their HCV infection, having a relationship with someone who injects drugs may place an individual at appreciable risk of being infected; such individuals should consider being tested for HCV.     

Emerging HIV infections with distinct subtypes of HIV-1 infection among injection drug users from geographically separate locations in Guangxi Province, China

Heroin users from Guangxi province, a southern province of China that borders Vietnam in the south and Yunnan province in China in the west, were studied for prevalence and risk factors for HIV-1 infection. Viral env sequences from HIV-1-positive individuals were also determined for subtypes of HIV-1. The overall HIV prevalence among 227 heroin users was 40%. Most had used drugs for < or = 3 years. Sharing of injection equipment and unprotected sex were significantly associated with HIV-1 infection. Subtypes C and E HIV-1 were detected in infected heroin users and were sharply segregated in two geographic locations: only subtype C was found in a border city with Yunnan province, whereas only subtype E was found in a city bordering northern Vietnam. HIV-1 strains within each subtype were remarkably homogenous, with a mean intersubject DNA distance of 2.32% for subtype E and 1.13% for subtype C, respectively. Phylogenetic analysis of C2-V5 region of Guangxi subtype E env sequences revealed significant clustering with subtype E sequences from southern Vietnam and Cambodia. These results suggest that HIV-1 infection among heroin users in Guangxi represents two emerging epidemics initiated from distinct sources: one from Vietnam and another from Yunnan province. Factors associated with HIV-1 infection were not restricted to injection practices. Unprotected sexual behaviors are likely to increase the probability of HIV transmission beyond this high-risk population. Designing and implementing effective intervention strategies targeted toward both injection drug use and high risk sexual behavior are urgently needed to further reduce HIV-1 spread in China.     

Prevalence of human immunodeficiency virus and its association with hepatitis B,C, and D virus infections among incarcerated male substance abusers in Taiwan

Taiwan has been facing a rising epidemic of human immunodeficiency virus (HIV) infection since 2004. Injection drug users comprised 38.5% of accumulated HIV cases by 2007. This cross‐sectional study investigated the seroprevalence of hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), and HIV infection in 753 male substance users who were detained in a detoxification center in Taoyuan, Taiwan. The subjects were enrolled into the study consecutively between February and October, 2005. The seroprevalence rates of HIV antibodies, HCV antibodies, and HBV surface antigens among all subjects, and HDV antibodies among HBV carriers were 6.9% (95% confidence interval [CI]: 5.19–8.95), 30.5% (95% CI: 27.23–33.93), 16.9% (95% CI: 14.24–19.71) and 13.7% (95% CI: 8.19–21.04), respectively. Subjects in the heroin injection group had significantly higher rates of HIV infection, HCV infection and HDV superinfection (25.5%, 89.6%, and 38.7%) than those in the heroin non‐injection group (0.9%, 24.5%, and 6.25%), the methamphetamine group (0.3%, 8.1%, and 6.7%), and the club drug group (1%, 3%, and 0%; P < 0.001). The odds of HCV, HIV, or HDV infection were 74.7, 63.8, and 11.1 higher, respectively, for heroin injection drug users than for non‐injection drug users (P < 0.0001). Compared to HIV‐negative individuals, the odds of being a heroin injector and the odds of HCV co‐infections were 64‐fold and 149‐fold higher, respectively, in HIV‐positive individuals. The impact of HBV, HCV, and HDV infection on the HIV epidemic in Taiwan should be monitored closely. J. Med. Virol. 81:973–978, 2009. © 2009 Wiley‐Liss, Inc.     

Prevalence trend and correlates of HHV-8 infection in HIV-infected patients

To assess the circulation of human herpesvirus (HHV)-8 infection over the years, two seroprevalence surveys were conducted, which tested sera from HIV-infected individuals recruited 10 years apart (206 individuals from 1986 to 1988 and 177 individuals from 1997 to 1998). For all patients, antibodies to hepatitis C virus (HCV), hepatitis B virus (HBV), and HHV-8 lytic and latent antigens were evaluated.HHV-8 seroprevalence was higher among individuals recruited in the 1990s (31.6% for anti-lytic, 8.5% for anti-latent antibodies) compared with similar findings in those seen in the late 1980s (14.6% and 3.4% for anti-lytic and anti-latent antibodies, respectively), with a twofold increase of the risk of HHV-8 infection. However, the increase was observed only among injecting drug users, whereas seroprevalence tended to slightly increase among those infected by sexual contact. At univariate analysis, time of recruitment and being homosexual men were factors associated with HHV-8 infection, an association that remained after adjusting for age. HBV infection was significantly associated with HHV-8 infection (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.3-3.6), whereas those infected with HCV had a lower probability of having HHV-8 antibodies (OR, 0.3; 95% CI, 0.20-0.6). After controlling for age and gender, time of recruitment remained independently associated with HHV-8 infection among injecting drug users.In conclusion, HHV-8 seroprevalence appears to be increased during 10 years among HIV-infected injection drug users but not among homosexual men, who remain those at the highest risk of infection.     

Hepatitis C virus genotype 3 and the risk of severe liver disease in a large population of drug users in France

Although risk factors for cirrhosis in chronic hepatitis C virus (HCV) infection have been identified, the role of HCV‐genotype 3 remains controversial, and limited data are available in drug users. The aim of the study was to assess risk factors for severe liver disease (cirrhosis/hepatocellular carcinoma) in HCV‐infected drug users between 2001 and 2007 in France. Patients who reported drug use and who had been referred for HCV infection to hepatology centers from a national surveillance system were identified. The severity of liver disease was assessed clinically and histologically (Metavir score). Factors associated with severe liver disease were analyzed after estimating missing values by multiple imputation (MI). Of the 4,065 drug users naive to anti‐HCV treatment who were referred to the 26 participating centers, 8.0% had severe liver disease, 25.7% were infected with HCV‐genotype 3. Factors associated independently with an increased risk of severe liver disease were HCV‐genotype 3 (adjusted odds ratio, multiple imputation (aOR_MI) = 1.6, [95% confidence interval, 95% CI: 1.2–2.1]), HIV infection (aOR_MI = 1.8, [1.2–2.8]), male sex (aOR_MI = 2.0, [1.4–2.8]), age over 40 years (aOR_MI = 2.1, [1.6–2.9]), history of excessive alcohol consumption (aOR_MI = 2.8, [2.1–3.7]), and duration of infection ≥18 years (aOR_MI = 2.9, [2.0–4.3]). This analysis shows that HCV‐genotype 3 is associated with severe liver disease in drug users, independently of age, sex, duration of infection, alcohol consumption, and co‐infection with HIV. These results are in favor of earlier treatment for drug users infected with HCV‐ genotype 3 and confirm the need for concomitant care for excessive alcohol consumption. J. Med. Virol. 82:1647–1654, 2010. 2010 Wiley‐Liss, Inc.     

Females experiencing sexual and drug vulnerabilities are at elevated risk for HIV infection among youth who use injection drugs

OBJECTIVES: To compare sociodemographic, drug-related, and sexual risk variables between young (13-24 years of age) and older (> or =25 years of age) injection drug users (IDUs); and to determine HIV prevalence and associated risk factors for HIV infection among young IDUs. METHODS: Data were collected through the Vancouver Injection Drug Users Study (VIDUS). To date, over 1400 Vancouver area IDUs have been enrolled and observed during follow-up. Sociodemographic, drug-related, and sexual risk variables were compared between younger and older IDUs using nonparametric methods. Mantel-Haenszel and logistic regression methods were used to compare HIV-positive and HIV-negative female youth. RESULTS: Younger injectors (N = 232) were more likely to be female; work in the sex trade; report condom use; inject heroin daily; smoke crack cocaine daily; and need help injecting. HIV prevalence at baseline among the youth was 10%. HIV prevalence was associated with female gender; history of sexual abuse; engaging in survival sex; injecting heroin daily; injecting speedballs (a mixture of heroin and cocaine) daily; and having numerous lifetime sexual partners. CONCLUSION: Our data show that HIV positivity among young IDUs is concentrated among females engaged in dual sexual and drug-related risk exposure categories. Over half the HIV-positive youth were Aboriginal (a classification used by the federal government in Canada to include native peoples of all ethnic groups). Targeted interventions that take into account sexual and drug risk for young female and Aboriginal peoples are urgently needed.     

Genetic variation of hepatitis C virus in a cohort of injection heroin users in Wuhan, China

Since the majority of heroin abusers use injection as the primary route of admission, heroin abuse contributes significantly to the transmission of hepatitis C virus (HCV). We determined HCV infection and its genotype distribution among injection heroin users in Wuhan, the largest city in the central China. Eight hundred seventy-eight (84%) out of 1046 serum specimens from the injection drug users were positive for HCV antibody. Out of randomly selected 122 specimens positive for HCV antibody, seventy-eight (64%) had detectable HCV RNA with genotype 6a as the predominant strain (50%), followed by 3b (32.2%), 1a (8.1%), 1b (6.5%), and 3a (3.2%). HCV RNA levels in male heroin users were significantly higher (P=0.013) than those in the female subjects. Although there was no significant difference in HCV RNA levels among the specimens positive for HCV 6a and 1a/1b, the samples with 6a or 1a/1b contained higher levels of HCV RNA than the specimens positive for HCV 3b (P=0.019, P=0.012, respectively). These findings indicate that there is a high prevalence of HCV infection with genotypes 6a and 3b as predominated strains among injection heroin users in Wuhan, China.     

Cocaine injection and ethnicity in parenteral drug users during the early years of the human immunodeficiency virus (HIV) epidemic in New York City

Parenteral drug users have a high prevalence of infection with human immunodeficiency virus (HIV), the etiologic agent of acquired immune deficiency syndrome (AIDS). New York City has had a prolonged and extensive epidemic of HIV infection and AIDS. In this study, we analyze, in relation to antibody to HIV (anti-HIV), available data from sera from parenteral drug users collected in New York City during 1978 through 1983 in the course of studies of liver disease. Among parenteral users of both heroin and cocaine, 30 (52%) of 58 had anti-HIV, compared with six (13%) of 48 injectors of heroin only (P less than 0.0001). Only two (11%) of 18 white patients were HIV-infected, compared with 34 (39%) of 88 black or Hispanic patients (P = 0.03). No other factors studied were linked to anti-HIV. In a multiple logistic regression, anti-HIV was significantly more common in parenteral users of both cocaine and heroin (P less than 0.0001), black patients (P = 0.02), and Hispanic patients (P = 0.049). We conclude that parenteral users of both cocaine and heroin as well as black and Hispanic patients were disproportionately HIV-infected during the early years of the HIV epidemic. Use of cocaine and heroin as well as ethnicity were independently linked to anti-HIV. Measures to prevent or treat drug use, HIV infection, and other medical problems while addressing the specific needs of cocaine users and black and Hispanic patients are urgently needed.     

HCV infection among cocaine users in the state of Pará, Brazilian Amazon

In this study, the prevalence, genotype frequency, and risk factors for HCV infection in 384 cocaine users were determined. One hundred twenty-four (32.3 %) cocaine users had anti-HCV antibodies and 120 (31.3 %) had HCV-RNA. Genotyping results indicated the predominance of genotypes 1 (73.3 %) and 3 (26.7 %). Multivariate analysis showed an association of HCV infection with tattoos, shared use of paraphernalia, daily cocaine use, and a long history of cocaine use. The epidemiological aspects of HCV infection among cocaine users presented here should serve as an incentive for the establishment of a program of hepatitis C prevention and control by the local public-health authorities in the Amazon.     

Hepatitis C infection among intravenous drug users attending therapy programs in Cyprus

The most high‐risk population for HCV transmission worldwide today are intravenous drug users. HCV genotypes in the general population in Cyprus demonstrate a polyphyletic infection and include subtypes associated with intravenous drug users. The prevalence of HCV, HBV, and HIV infection, HCV genotypes and risk factors among intravenous drug users in Cyprus were investigated here for the first time. Blood samples and interviews were obtained from 40 consenting users in treatment centers, and were tested for HCV, HBV, and HIV antibodies. On the HCV‐positive samples, viral RNA extraction, RT‐PCR and sequencing were performed. Phylogenetic analysis determined subtype and any relationships with database sequences and statistical analysis determined any correlation of risk factors with HCV infection. The prevalence of HCV infection was 50%, but no HBV or HIV infections were found. Of the PCR‐positive samples, eight (57%) were genotype 3a, and six (43%) were 1b. No other subtypes, recombinant strains or mixed infections were observed. The phylogenetic analysis of the injecting drug users' strains against database sequences observed no clustering, which does not allow determination of transmission route, possibly due to a limitation of sequences in the database. However, three clusters were discovered among the drug users' sequences, revealing small groups who possibly share injecting equipment. Statistical analysis showed the risk factor associated with HCV infection is drug use duration. Overall, the polyphyletic nature of HCV infection in Cyprus is confirmed, but the transmission route remains unknown. These findings highlight the need for harm‐reduction strategies to reduce HCV transmission. J. Med. Virol. 82:263–270, 2010. © 2009 Wiley‐Liss, Inc.     

Changes in HIV-1 incidence in heroin users in Guangxi Province, China

Guangxi Province, China recently experienced an outbreak of HIV-1 infection among heroin users. We studied HIV-1 incidence rates and associated risk factors for HIV-1 infection among heroin users residing in Pingxiang City. A total of 318 heroin users were followed from February 1998 through January 1999 (median follow-up: 8.1 months). Of these, 130 were prospectively followed from January through September 1999 (median follow-up: 8.3 months). HIV-1 and hepatitis C virus (HCV) incidence rates for each period were calculated. A generalized estimating equation approach was implemented to identify independent risk factors associated with HIV-1 infection across both periods. Among 318 study participants, 97.2% were men. The median age was 22 years. Approximately 60% reported sharing needles. HIV-1 prevalence at baseline was 15.4%. During the first follow-up period, HIV-1 incidence was 2.38 per 100 person years (py), and HCV incidence was 26.8 per 100 py. During the second follow-up period, HIV-1 incidence was 6.86 per 100 py, and HCV incidence was 28.9 per 100 py. After controlling for age and other factors, HCV seropositivity, history of sexually transmitted diseases, and sharing needles were independently associated with HIV-1 infection. These data suggest that HIV-1 incidence was rising over time in Pingxiang City, Guangxi Province. The high incidence of HCV heightens the importance of enhanced prevention programs to reduce injection and needle sharing among heroin users.     

Factors associated with hepatitis C viremia in a large cohort of HIV-infected and -uninfected women.

BACKGROUND: Co-infection with hepatitis C virus (HCV) is common among HIV-infected women. OBJECTIVE: To further our understanding of the risk factors for HCV viremia and the predictors of HCV viral load among women. STUDY DESIGN: We investigated sociodemographic, immunologic, and virologic factors associated with presence and level of HCV viremia among 1049 HCV-seropositive women, 882 of whom were HIV-infected and 167 HIV-uninfected at their entry into the Women's Interagency HIV Study. RESULTS: Plasma HCV RNA was detected in 852 (81%) of these 1049 women (range: 1.2-7.8 log(10)copies/ml). HCV-viremic women were more likely to have an HIV RNA level >100,000 copies/ml (P=0.0004), to have reported smoking (P=0.01), or to be Black (P=0.005). They were less likely to have current or resolved hepatitis B infection. HCV RNA levels were higher in women who were >35 years old, or HIV-infected. Current smoking and history of drug use (crack/freebase cocaine, marijuana, amphetamines, or heroin) were each associated with both presence and level of viremia. CONCLUSIONS: Substance abuse counseling aimed at eliminating ongoing use of illicit drugs and tobacco may reduce clinical progression, improve response to treatment, and decrease HCV transmission by lowering levels of HCV viremia in women.     

The future face of coinfection: prevalence and incidence of HIV and hepatitis C virus coinfection among young injection drug users

The purpose of this study was to determine the prevalence and incidence of HIV and hepatitis C virus (HCV) coinfection among young (aged 29 years or younger) injection drug users (IDUs) and to compare sociodemographic and risk characteristics between (HIV/HCV) coinfected, monoinfected, or HIV- and HCV-negative youth. Data were collected through the Vancouver Injection Drug Users Study (VIDUS). To date, more than 1400 IDUs have been enrolled and followed, of whom 479 were aged 29 years or younger. Semiannually, participants have completed an interviewer-administered questionnaire and have undergone serologic testing for HIV and HCV. Univariate and multivariate logistic regression analyses were undertaken to investigate predictors of baseline coinfection. Cox regression models with time-dependent covariates were used to identify predictors of time to secondary infection seroconversion. A Cochran-Armitage trend test was used to determine risk associations across 3 categories: no infection, monoinfection, and coinfection. Of the 479 young injectors, 78 (16%) were coinfected with HIV and HCV at baseline and a further 45 (15%) with follow-up data became coinfected during the study period. Baseline coinfection was independently associated with being female, being aboriginal, older age, greater number of years injecting, and living in the IDU epicenter. Factors independently associated with time to secondary infection seroconversion were borrowing needles and greater than once-daily cocaine injection, and accessing methadone maintenance therapy in the previous 6 months was protective. There were clear trends across the 3 categories for increasing proportions of female subjects, aboriginal subjects, older age, greater number of years injecting, living in the IDU epicenter, and daily cocaine use. There were a shocking number of youth living with coinfection, particularly female and aboriginal youth. The median number of years injecting for youth seroconverting to a secondary infection was 3 years, suggesting that appropriate public health interventions should be implemented immediately.     

Risk behaviors for HCV- and HIV-seroprevalence among female crack users in Porto Alegre, Brazil

Several studies have shown a high prevalence of HIV-seropositive status among crack users, though most refer to North American populations. Few studies evaluate HCV prevalence among female crack users. In addition, there is a particular lack of data about risk behaviors and HIV/HCV prevalence in this population around the world. In order to ascertain the HIV/HCV serostatus and associated risk behaviors for infection of female crack users of Porto Alegre, Brazil. A cross-sectional study of a convenience sample of 73 current female crack users was conducted. Subjects answered NIDA’s Risk Behavior Assessment and an AIDS Information Questionnaire. In addition, blood was collected from subjects for HIV/HCV tests. The overall prevalence of HIV was 37.0%; HCV seroprevalence was 27.7%; of 15.1% the sample was co-infected with HIV and HCV. Four years of schooling or fewer (OR 4.72–CI 95%; 1.49–14.99) and having three or more HIV tests in one’s lifetime (OR 4.26–CI 95% (1.29–14.04)) were associated with HIV infection (after multivariate logistic regression). The single greatest risk factor for HCV infection was having 4 years of schooling or fewer (OR 4.51–CI 95%; 1.18–17.27). We found a very high prevalence of HIV and HCV infection among female crack users, and low education was the most significant risk factor associated with both infections.     

Molecular and epidemiological aspects of hepatitis C virus infection among crack cocaine users

The aim is to investigate the prevalence, risk factors, and hepatitis C virus (HCV) genotypes/subtypes among crack users in-treatment in Central Brazil. A cross-sectional survey in which 600 in-treatment crack users were interviewed and tested for anti-HCV Ab by enzyme-linked immunosorbent assay was conducted between August 2012 and April 2013. Anti-HCV-positive samples were also submitted for HCV RNA detection by polymerase chain reaction. Positive HCV RNA samples were genotyped by direct sequencing analysis of the NS5B region of the viral genome, followed by phylogenetic analysis. Of the total, 3.7% (95.0% CI, 2.4%-5.6%) were anti-HCV positive. Age over 40 years and history of injecting drugs were risk factors for HCV, while snorting cocaine was a protector variable. HCV RNA was detected in 14 of 22 anti-HCV-positive samples, and the genotypes 1 (n = 10) and 3 (n = 2), subtypes 1a (n = 7), 1b (n = 3), and 3a (n = 2) were identified. The HCV prevalence found among crack users is almost threefold that observed in the general population in Brazil supporting that this population is at higher risk for HCV. The findings of cocaine insufflation as a protective behavior for HCV infection in this population should be explored.     

Incidence and risk factors for hepatitis C among injection drug users in Baltimore, Maryland.

Between 1988 and 1996, the incidence of and risk factors for hepatitis C virus (HCV) infection were studied in a cohort of injection drug users in Baltimore, Maryland. By second-generation antibody testing of stored serum samples, 142 participants were found to be susceptible to HCV at the time they entered the study. After a median follow-up of 6.5 years, 43 participants (30.3%) developed antibodies to HCV (anti-HCV). The overall incidence was 6.4 cases per 100 person-years, but a substantial decline in the annual incidence rate was observed after the first 2 years (1988 to 1990, 13.4/100 person-years; 1991 to 1996, 2.3/100 person-years [P = 0.0001 for trend]). Participants who acknowledged active drug use, especially those who acknowledged frequent use and sharing of drug paraphernalia, were at increased risk of HCV infection. However, high-risk sexual practices were not associated with HCV seroconversion. Efforts to reduce HCV infection must be focused on curbing drug use and especially on the sharing of needles and drug paraphernalia.