South America is considered to have a low prevalence of hepatitis B virus (HBV) infection, although areas with a relatively high prevalence have been identified in northern Brazil. Few epidemiological studies of populations at risk of HBV infection are available for this region. Given this, in the present study, we investigated the prevalence of HBV and the factors associated with infection among illicit drug users (DUs) in the Marajó Archipelago, northern Brazil. In this cross-sectional study, we collected samples and epidemiological information from DUs in 11 municipalities of the Marajó Archipelago. The diagnosis was established by ELISA and real-time PCR; and genotyping was done by multiplex real-time PCR. Statistical modeling was based on simple and multiple logistical regressions with the Hosmer-Lemeshow test. The mean age of the 466 DUs was 28.4 years, and most were male. The most-consumed illicit drugs were crack cocaine and marijuana. In all, 171 DUs were exposed to HBV, with genotypes A, D and F being identified. The factors associated with higher frequencies of HBV infection were (i) male gender, (ii) age above 35 years, (iii) anti-HIV positivity, (iv) tattoos, (v) the use of injected drugs, (vi) the use of illicit drugs for more than 3 years, (vii) sexual relations without protection, (viii) sexual relations with another DU, and (ix) more than 10 sexual partners in the past 24 months. In summary, this study provides important insights into the dynamics of HBV infection among DUs in the Marajó Archipelago. We hope that these findings will contribute to the development of strategies, actions and public health policies aimed at preventing and controlling this viral infection more effectively.

Hepatitis C virus (HCV) infection causes acute and chronic liver disease and may lead to cirrhosis, liver failure or hepatocellular carcinoma. The behavior of illicit drug users (DUs) typically exposes them to risks of viral infection. In the Brazilian Amazon region, a number of studies have identified high rates of drug use among adolescents, and a high prevalence of HBV infection in DUs, disseminated by sexual and parenteral activities. However, the epidemiological scenario of HCV infection in the region is still poorly understood. This study determined the prevalence, genotypes, and risk factors for HCV infection among DUs of the Marajó Archipelago. This cross-sectional study collected samples and epidemiological information from DUs in 11 municipalities. The diagnosis was established by EIA and real-time PCR, and the samples were genotyped by multiplex real time PCR. The data were analyzed by simple and multiple logistical regression. In 466 DUs, 28.3% had anti-HCV antibodies, and 25.5% had HCV-RNA. In 92 injecting drug users, 88.0% had anti-HCV antibodies, and 80.4% had HCV-RNA. Genotypes 1 and 3 were detected, with three cases of mixed infections. The multivariate analysis indicated associations of HCV infection with age (≥ 35 years), tattoos, intravenous drug use, shared use of injection equipment, and the daily and long-term (> 3 years) use of illicit drugs. These findings will contribute to the development of effective measures for the prevention of HCV infection among Brazilian DUs, as well as its general population.

Introduction: Illicit drug users (DUs) are vulnerable to hepatitis C virus (HCV) infection. The shared use of illicit drugs is the main method of HCV transmission. Methods: A cross-sectional study was conducted in Breves, in northern Brazil. We surveyed 187 DUs to determine the prevalence of and factors associated with HCV infection. Results: The prevalence of anti-HCV antibodies was 36.9%, and the prevalence of hepatitis C virus-ribonucleic acid (HCV-RNA) was 31%. Hepatitis C virus infection was associated with tattoos, intravenous drug use, shared use of equipment for drug use, drug use for longer than 3 years, and daily drug use. Conclusions: Strategies for preventing and controlling HCV transmission should be implemented among DUs.Keywords: Hepatitis C virus. Illicit drug users. Northern Brazil.Currently, the sharing of drug paraphernalia is the main transmission method for hepatitis C virus (HCV) worldwide. It is estimated that more than 60% of new HCV infection cases recorded each year are related to the use of illicit drugs, particularly injected drugs 1,2 . In Brazil, epidemiological studies of HCV infection in illicit drug users are still rare. The prevalence of HCV infection in illicit drug users sampled in metropolitan areas in the Northeast, Midwest, South and Southeast regions of Brazil ranged from 5% to 36% 3-7 . There are frequent reports of clinical cases of hepatitis or pathologies associated with HCV infection in other population groups in northern Brazil [8][9][10][11] . It is known that most illicit drug users in Pará do not consume injected drugs and are infected with HCV genotype 1 10,11 . This study estimated the prevalence of HCV infection and assessed the factors associated with HCV infection in illicit drug users in the municipality of Breves, State of Pará, northern Brazil.This cross-sectional study of a non-probabilistic convenience sample was based on information and biological samples provided by illicit drug users in an area of intense illicit drug use located in Breves (01° 40' 55" S 50° 28' 48" O), Archipelago of Marajó, Pará, northern Brazil. Illicit drug users in areas of intense drug consumption were sampled using the snowball technique 11 . Individuals were eligible for the study if they were older than 17 years of age and agreed to answer a specifi c questionnaire and have a blood sample taken and tested for molecular and serologic markers in the period from August to All samples were tested for HCV antibodies and hepatitis C virus-ribonucleic acid (HCV-RNA). Anti-HCV antibodies were tested by enzyme immunoassay (EIA; Murex anti-HCV 4.0, Murex Biotech). HCV RNA was detected by real-time polymerase chain reaction (PCR) using 67 base pairs of the 5' untranslated region (UTR), as described elsewhere 9 . Confi dence intervals (CIs) were determined for infection prevalence estimates. Simple and multiple logistic regressions were calculated to assess the independent effects of variables 12 . The fi t of the fi nal model was assessed using the Hosmer-Lemeshow goodness-of-f...