Hepatitis B and C in the hemodialysis unit of Tocantins,Brazil: serological and molecular profiles

A survey was conducted in the hemodialysis population of the state of Tocantins, Brazil, aiming to assess the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, to analyze associated risk factors, and also to investigate these viruses genotypes distribution. During January and March 2001, all patients (n = 100) were interviewed at the unique dialysis unit in Tocantins. Blood samples were collected and serum samples were screened for HBV serological markers. Hepatitis B surface antigen positive samples were tested for HBV DNA. All samples were also tested for anti-HCV antibodies and HCV RNA. An overall prevalence of 45% was found for HBV infection (4% were HBsAg/anti-HBc positive, 2% were anti-HBc only and 39% had anti-HBc/anti-HBs markers). Concerning HCV infection, anti-HCV and HCV RNA were detected in 13% and 14% of the subjects, respectively. Three patients were HCV RNA positive and anti-HCV negative, resulting in an overall HCV prevalence of 16%. Univariate analysis of risk factors showed that only shift and length of tile on hemodialysis were associated with HBV and HCV positivity respectively. Among the four HBsAg-positive samples, HBV DNA was detected in three of them, which were identified as genotype A by restriction fragment length polymorphism (RFLP) analysis. All 14HCV RNA-positive samples were genotyped by INNO-LiPA. Genotypes la and 3a were found in 85% and 15%, respectively. The present data show low HBsAg and HCV prevalence rates. The risk factors associated with HBV and HCV positivity suggest that nosocomial transmission may influence in spreading these viruses in the dialysis unit studied.     

Occult hepatitis B virus infection among injecting drug users in the Central-West Region of Brazil

The prevalence of occult hepatitis B virus (HBV) infection was investigated in 149 hepatitis B surface antigen (HBsAg) negative injecting drug users (IDUs) in the Central-West Region of Brazil. Of these individuals, 19 were positive for HBV DNA, resulting in an occult HBV infection prevalence of 12.7% (19/149); six of these 19 individuals had anti-HBV core and/or anti-HBV surface antibodies and 13 were negative for HBV markers. All IDUs with occult hepatitis B reported sexual and/or parenteral risk behaviours. All HBV DNA-positive samples were successfully genotyped. Genotype D was the most common (17/19), followed by genotype A (2/19). These findings reveal a high prevalence of occult HBV infection and the predominance of genotype D among IDUs in Brazil''s Central-West Region.     

Prevalence, genotypes and risk factors associated with hepatitis C virus infection in hemodialysis patients in Campo Grande, MS, Brazil

A survey was conducted among the hemodialysis units of the city of Campo Grande, located in the state of Mato Grosso do Sul in the Mid-west region of Brazil, with the aim of investigating the prevalence, risk factors, and genotypes of hepatitis C virus (HCV) infection. A total of 163 patients were interviewed in five dialysis units. Serum samples were screened for anti-HCV. Positive samples were tested for HCV RNA and genotyped. The prevalence of anti-HCV was 11% (95% CI: 6.8-17.1). A history of transfusion with blood that was not screened for anti-HCV and length of time on hemodialysis were associated with HCV infection. HCV RNA was detected in 12 samples: ten were of genotype 1, subtypes 1a (75%) and 1b (8.3%), and two were of genotype 3, subtype 3a (16.7%).     

Hepatitis C prevalence and risk factors in hemodialysis patients in Central Brazil: a survey by polymerase chain reaction and serological methods

An hemodialysis population in Central Brazil was screened by polymerase chain reaction (PCR) and serological methods to assess the prevalence of hepatitis C virus (HCV) infection and to investigate associated risk factors. All hemodialysis patients (n=428) were interviewed in eight dialysis units in Goiania city. Blood samples were collected and serum samples screened for anti-HCV antibodies by an enzyme-linked immunosorbent assay (ELISA). Positive samples were retested for confirmation with a line immunoassay (LIA). All samples were also tested for HCV RNA by the PCR. An overall prevalence of 46.7% (CI 95%: 42-51.5) was found, ranging from 20.7% (CI 95%: 8.8-38.1) to 90.4% (CI 95%: 79.9-96.4) depending on the dialysis unit. Of the 428 patients, 185 were found to be seropositive by ELISA, and 167 were confirmed positive by LIA, resulting in an anti-HCV prevalence of 39%. A total of 131 patients were HCV RNA-positive. HCV viremia was present in 63.5% of the anti-HCV-positive patients and in 10.3% of the anti-HCV-negative patients. Univariate analysis of risk factors showed that the number of previous blood transfusions, transfusion of blood before mandatory screening for anti-HCV, length of time on hemodialysis, and treatment in multiple units were associated with HCV positivity. However, multivariate analysis revealed that blood transfusion before screening for anti-HCV and length of time on hemodialysis were significantly associated with HCV infection in this population. These data suggest that nosocomial transmission may play a role in the spread of HCV in the dialysis units studied. In addition to anti-HCV screening, HCV RNA detection is necessary for the diagnosis of HCV infection in hemodialysis patients.     

Occurrence of hepatitis viruses in wild-born non-human primates: a 3 year (1998-2001) epidemiological survey in Gabon

Hepatitis B and C infections are endemic in human population in central Africa, particularly in Gabon. The aim of this study was to determine the prevalence of hepatitis B virus (HBV) and eventual occurrence of hepatitis C virus (HBC)-related strains in a variety of wild-born non-human primates living in Gabon and Congo. Plasma samples were screened for HBV and HCV markers. A non-invasive method of DNA extraction from faeces followed by specific HBV-DNA amplification was developed to study this infection in wild troops of chimpanzees and gorillas. No HCV infection in non-human primates, wild-born or captive, was detected among 596 samples tested. No HBV infection could be detected in samples tested and obtained from Cercopithecidae. In contrast, 14.7 and 42.2% of wild-born chimpanzees in Gabon and Congo were infected with HBV or had evidence of past HBV infection. At Centre International de Recherches Médicales (CIRMF) Primate Centre, 32.1% of chimpanzees and gorillas were HBV positive or had evidence of past infection. In the cases with past infection, 5.9% wild-born and 8.3% at CIRMF harboured HBV-DNA despite the presence of neutralizing HbsAb. Together with previous findings, we confirm the high HBV prevalence not only in humans but also in chimpanzees and gorillas in Gabon and Congo.     

Rare Detection of Occult Hepatitis B Virus Infection in Children of Mothers with Positive Hepatitis B Surface Antigen

The prevalence of occult Hepatitis B virus (HBV) infection in children was considerably varied from 0.1–64% in different reports. In this study we aimed to investigate the prevalence of occult HBV infection among the children born to mothers with positive hepatitis B surface antigen (HBsAg) in Jiangsu, China. Serum samples were collected from 210 children of 207 mothers with positive HBsAg. HBV serological markers were detected by ELISA and HBV DNA was detected by nested PCR. Homology comparison of HBV sequences recovered from the child and mother was used to define the infection. Three children (1.43%) were positive for HBsAg, in whom the HBV pre S and S gene sequence in each child was identical to that in her mother. Of the 207 HBsAg-negative children, nine displayed HBV DNA positive by two nested PCR assays using primers derived from S and C genes. However, the sequence alignment showed that the sequences in each child were considerably different from those in his/her mother. Therefore, the sequences amplified from the children were very likely resultant from the cross-contaminations. Furthermore, the nine children with ‘positive HBV DNA’ were all negative for anti-HBc, and one had anti-HBs 3.42 mIU/ml and eight others had anti-HBs from 72 to >1000 mIU/ml, indicating that the nine children were less likely infected with HBV. Therefore, none of the 207 HBsAg-negative children of HBV-infected mothers was found to have occult HBV infection. We conclude that the prevalence of occult HBV infection in vaccinated children born to HBsAg positive mothers should be extremely low. We recommend that homology comparison of sequences recovered from the child and mother be used to define the occult HBV infection in children born to HBV infected mothers.     

Hepatitis B infection among patients attending a sexually transmitted diseases clinic in Rio de Janeiro, Brazil

Hepatitis B virus (HBV) has a low endemicity in Rio de Janeiro, Brazil. Sexual transmission must play an important role in this virus, but the prevalence and risk factors have never been properly investigated. The aim of this paper is to determine the prevalence and risk factors for HBV infection in patients attending a Sexually Transmitted Diseases Clinic of the Universidade Federal Fluminense, from the State of Rio de Janeiro, Brazil. In a retrospective study, HBV seroprevalence was investigated in 440 patients. Serum of each patient was assayed for antibodies against hepatitis B core antigen (anti-HBc), hepatitis B surface antigen (HBsAg) and antibodies against hepatitis B surface antigen (anti-HBs). Demographic and risk factor data were extracted from clinic notes. The overall seroprevalence of exposure markers for HBV (anti-HBc, HBsAg and anti-HBs) were 13%, 3.4% and 8.5% respectively. Homo/bisexual behaviour, anal intercourse, HIV infection, positive serology for syphilis and blood transfusion were predictors of the HBV exposure. Among demographic data, age and place of birth were associated with the anti-HBc seropositivity.     

Patterns of hepatitis B virus infection in Brazilian human immunodeficiency virus infected patients: high prevalence of occult infection and low frequency of lamivudine resistant mutations

Hepatitis B virus (HBV) molecular profiles were determined for 44 patients who were infected with human immunodeficiency virus (HIV) type 1 and had antibodies to the hepatitis B core antigen (anti-HBc), with and without other HBV serological markers. In this population, 70% of the patients were under lamivudine treatment as a component of antiretroviral therapy. HBV DNA was detected in 14 (32%) patients. Eight out of 12 (67%) HBsAg positive samples, 3/10 (30%) anti-HBc only samples, and 3/22 (14%) anti-HBs positive samples were HBV DNA positive. HBV DNA loads, measured by real time polymerase chain reaction, were much higher in the HBsAg positive patients (mean, 2.5 x 10(9) copies/ml) than in the negative ones (HBV occult infection; mean, 2.7 x 10(5) copies/ml). Nine out of the 14 HBV DNA positive patients were under lamivudine treatment. Lamivudine resistant mutations in the polymerase gene were detected in only three patients, all of them belonging to the subgroup of five HBsAg positive, HBV DNA positive patients. A low mean HBV load (2.7 x 10(5) copies/ml) and an absence of lamivudine resistant mutations were observed among the cases of HBV occult infection.     

Decline of hepatitis C infection in hemodialysis patients in Central Brazil: a ten years of surveillance

Hepatitis C virus (HCV) has been a significant problem for hemodialysis patients. However this infection has declined in regions where the screening for anti-HCV in blood banks and hemodialysis-specific infection control measures were adopted. In Brazil, these measures were implemented in 1993 and 1996, respectively. In addition, all studied units have implemented isolation of anti-HCV positive patients since 2000. In order to evaluate the impact of these policies in the HCV infection prevalence, accumulated incidence, and risk factors in hemodialysis population of Goiania City, Central Brazil, all patients were interviewed and serum samples tested for HCV antibodies in 1993, 1996, 1999, and 2002. In the first six years (1993-1999), anti-HCV prevalence increased from 28.2 to 37.2%, however a b decrease in positivity was detected between 1999 and 2002 (37.8 vs 16.5%) when the measures were fully implemented. Also, a decrease of the anti-HCV accumulated incidence in cohorts of susceptible individuals during 1993-2002 (71%), 1996-2002 (34.2%), and 1999-2002 (11.7%) was found. Analysis of risk factors showed that length of time on hemodialysis, blood transfusion before screening for anti-HCV and treatment in multiple units were statistically associated with anti-HCV (p < 0.05). Our study showed a significant decline of hepatitis C infection in hemodialysis patients of Central Brazil, gratifying the importance of public health strategies for control and prevention of hepatitis C in the hemodialysis units.     

Low frequency of precore mutants in anti-hepatitis B e antigen positive subjects with chronic hepatitis B virus infection in Chennai, Southern India

The natural course of chronic hepatitis B (CH-B) virus infection is reportedly variable, and the long-term outcomes in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B infection are distinct from HBeAg-positive chronic hepatitis. However, the molecular virological factors that contribute to the progression of liver disease in the south Indian setting remain largely unclear. We prospectively studied 679 consecutive patients for HBsAg, HBeAg, anti-HBeAg, and HBV DNA by qualitative PCR. Randomly selected samples were subjected to bidirectional sequencing to reveal core/precore variants. Of the total 679 chronic HBV cases investigated, 23% (154/679) were replicative HBV carriers. Furthermore, amongst the 560 HBV DNA samples analyzed, 26% (146/560) were viremic. Among the 154 HBeAg positive cases, HBV DNA was positive in 118 cases (77%), significantly (p<0.001) higher than the anti-HBe positive (7%) (28/406) cases. Significant increase in liver disease (p<0.01) with ALT enzyme elevation (p<0.001) was observed in both HBe and anti-HBe viremic cases. Interestingly, low frequencies of mutations were seen in the precore region of the HBV strains studied. HBV precore and core promoter variants were less often detected in subjects with "e" negative chronic HBV infection and, therefore, may not have a prognostic role in determining liver disease sequelae in this part of tropical India.     

Seroprevalence of viral hepatitis in riverine communities from the Western Region of the Brazilian Amazon Basin.

The western region of the Brazilian Amazon Basin has long been shown to be a highly endemic area for hepatitis B and hepatitis D viruses. Data concerning the prevalence of hepatitis C and E viruses in this region are still scarce. In this study we investigated the presence of hepatitis A, B, C, D and E viruses infection in communities that live along the Purus and Acre rivers in the states of Acre and Amazonas within the Amazon Basin. A total of 349 blood samples were collected and tested for hepatitis A-E serological markers (antibodies and/or antigens) using commercial enzyme linked immunosorbent assays. Anti-HCV positive sera were further assayed by an immunoblot. HBsAg positive sera were subtyped by immunodifusion. The overall prevalence for hepatitis A, B, C, and E were 93.7%, 66.1%, 1.7%, and 4%, respectively. A very high prevalence of delta hepatitis (66.6%) was found among HBsAg positive subjects. Hepatitis A, B and D viruses were shown to be largely disseminated in this population, while hepatitis C and E viruses infection presented low prevalence rates in this region. The analysis of risk factors for HBV infection demonstrated that transmission was closely associated with sexual activity.     

Epidemiological aspects of hepatitis C virus infection among renal transplant recipients in Central Brazil

An investigation was conducted involving 255 renal transplant recipients in the state of Goiás, Central Brazil, to determine the prevalence of hepatitis C virus (HCV), its risk factors, the genotypes involved, and the level of alanine aminotransferase (ALT) present in the patients. All serum samples were tested for anti-HCV antibodies and HCV RNA. Forty-one patients were anti-HCV and/or HCV RNA positive, resulting in an overall HCV infection prevalence of 16.1% (95% CI: 11.9-21.3). A multivariate analysis of risk factors showed that a history of blood transfusions without anti-HCV screening, the length of time spent on hemodialysis, and renal transplantation before 1994 are all associated with HCV positivity. In HCV-positive patients, only 12.2% had ALT levels above normal. Twenty-eight samples were genotyped as genotype 1, subtypes 1a (62.5%) and 1b (31.3%), and two samples (6.2%) were genotype 3, subtype 3a. These data show a high prevalence of HCV infection and low ALT levels in the studied population. The risk factor analysis findings emphasize the importance of public health strategies such as anti-HCV screening of candidate blood and organ donors, in addition to the stricter adoption of hemodialysis-specific infection control measures. The present study also demonstrates that HCV genotype 1 (subtype 1a) is predominant in this population.     

High prevalence of occult hepatitis B virus genotype H infection among children with clinical hepatitis in west Mexico

Studies on the prevalence of infection with hepatitis B virus (HBV) among children are scarce in Latin American countries, especially in Mexico. This study was aimed to investigate the prevalence of HBV infection, occult hepatitis B infection (OBI) and HBV genotypes among children with clinical hepatitis. In total, 215 children with clinical hepatitis were evaluated for HBV infection. HBV serological markers and HBV DNA were analysed. OBI diagnosis and HBV genotyping was performed. HBV infection was found in 11.2% of children with clinical hepatitis. Among these HBV DNA positive-infected children, OBI was identified in 87.5% (n = 21/24) of the cases and 12.5% (n = 3/24) were positive for both HBV DNA and hepatitis B surface antigen. OBI was more frequent among children who had not been vaccinated against hepatitis B (p < 0.05) than in those who had been vaccinated. HBV genotype H was prevalent in 71% of the children followed by genotype G (8%) and genotype A (4%). In conclusion, OBI is common among Mexican children with clinical hepatitis and is associated with HBV genotype H. The results show the importance of the molecular diagnosis of HBV infection in Mexican paediatric patients with clinical hepatitis and emphasise the necessity of reinforcing hepatitis B vaccination in children.     

Epidemiology,Risk Factors and Genotypes of HBV in HIV-Infected Patients in the Northeast Region of Colombia: High Prevalence of Occult Hepatitis B and F3 Subgenotype Dominance

Introduction

Chronic hepatitis B virus (HBV) infection is an increasing cause of morbidity and mortality in human immunodeficiency virus (HIV)-infected individuals. HIV-positive patients are commonly co-infected with HBV due to shared routes of transmission.

Objectives

Our aim was to determine the risk factors, prevalence, genotypes, and mutations of the Surface S gene of HBV, and occult hepatitis B infection (OBI) among patients infected with HIV in a northeastern Colombian city.

Methods

A cross-sectional study was conducted with 275 HIV-positive patients attending an outpatient clinic in Bucaramanga, Colombia during 2009–2010. Blood samples were collected and screened for serological markers of HBV (anti-HBs, anti-HBc and HBsAg) through ELISA assay. Regardless of their serological profile, all samples were tested for the HBV S gene by nested-PCR and HBV genotypes were determined by phylogenetic inference. Clinical records were used to examine demographic, clinical, virological, immunological and antiretroviral therapy (ART) variables of HIV infection.

Results

Participants were on average 37±11 years old and 65.1% male. The prevalence of HIV-HBV coinfection was 12% (95%CI 8.4–16.4) of which 3.3% had active HBV infection and 8.7% OBI. The prevalence of HIV-HBV coinfection was associated with AIDS stage and ART treatment. Sequence analysis identified genotype F, subgenotype F3 in 93.8% of patients and genotype A in 6.2% of patients. A C149R mutation, which may have resulted from failure in HBsAg detection, was found in one patient with OBI.

Conclusions

The present study found a high prevalence of HIV-HBV coinfection with an incidence of OBI 2.6-fold higher compared to active HBV infection. These findings suggest including HBV DNA testing to detect OBI in addition to screening for HBV serological markers in HIV patients.     

A multicentre molecular analysis of hepatitis B and blood-borne virus coinfections in Viet Nam

Hepatitis B (HBV) infection is endemic in Viet Nam, with up to 8.4 million individuals estimated to be chronically infected. We describe results of a large, multicentre seroepidemiological and molecular study of the prevalence of HBV infection and blood-borne viral coinfections in Viet Nam. Individuals with varying risk factors for infection (n = 8654) were recruited from five centres; Ha Noi, Hai Phong, Da Nang, Khanh Hoa and Can Tho. A mean prevalence rate of 10.7% was observed and levels of HBsAg were significantly higher in injecting drug users (IDUs) (17.4%, n = 174/1000) and dialysis patients (14.3%, n = 82/575) than in lower-risk groups (9.4%; p<0.001). Coinfection with HIV was seen in 28% of HBV-infected IDUs (n = 49/174) and 15.2% of commercial sex workers (CSWs; n = 15/99). HCV infection was present in 89.8% of the HBV-HIV coinfected IDUs (n = 44/49) and 40% of HBV-HIV coinfected CSWs (n = 16/40). Anti-HDV was detected in 10.7% (n = 34/318) of HBsAg positive individuals. Phylogenetic analysis of HBV S gene (n = 187) showed a predominance of genotype B4 (82.6%); genotypes C1 (14.6%), B2 (2.7%) and C5 (0.5%) were also identified. The precore mutation G1896A was identified in 35% of all specimens, and was more frequently observed in genotype B (41%) than genotype C (3%; p<0.0001). In the immunodominant 'a' region of the surface gene, point mutations were identified in 31% (n = 58/187) of sequences, and 2.2% (n = 4/187) and 5.3% (n = 10/187) specimens contained the major vaccine escape mutations G145A/R and P120L/Q/S/T, respectively. 368 HBsAg positive individuals were genotyped for the IL28B SNP rs12979860 and no significant association between the IL28B SNP and clearance of HBsAg, HBV viral load or HBeAg was observed. This study confirms the high prevalence of HBV infection in Viet Nam and also highlights the significant levels of blood-borne virus coinfections, which have important implications for hepatitis-related morbidity and development of effective management strategies.     

Hepatitis C and hepatitis B virus infection in different hemodialysis units in Belo Horizonte,Minas Gerais,Brazil

The prevalence, virological and epidemiological aspects of the hepatitis C virus (HCV) and the hepatitis B virus (HBV) infections vary among hemodialysis patients in different countries. Aiming at analyzing these aspects of HCV and HBV infections in hemodialysis patients in Belo Horizonte, MG, Brazil, we studied three hemodialysis units including 434 patients. Serology was used to detect anti-HCV and HBsAg. Reverse trancriptase nested polymerase chain reaction (RT-nested-PCR) of the 5'-noncoding region was used to detect circulating HCV RNA and restriction fragment length polymorphism analysis for genotyping. Seroprevalence varied from 26.5% to 11.1% for hepatitis C and from 5.9% to 0% for hepatitis B. Risk factors observed for HBV and/or HCV infections were the number of patients per dialysis unit, duration of treatment, number of clinics attended, number of blood units transfused, and lower level scholarity. Alanine aminotransferase levels were altered with a higher frequency in HBV or HCV seropositive patients. Half of ten patients, negative for anti-HCV, had detectable viremia by RT-nested-PCR, indicating that this technique should be used to confirm infections in this group of patients. The HCV genotype 1 was the most frequently observed, followed by the genotype 2, but no correlation was detected between genotype and clinical or epidemiological data.     

Seroprevalence of Hepatitis B virus infection among an Afro-descendant community in Brazil

Furnas dos Dionísios is an Afro-Brazilian black community whose descendants were mainly fugitive slaves that established themselves in the State of Mato Grosso do Sul (MS), Brazil. The population is comprised mainly of low socioeconomic individuals who are engaged in agricultural activities. The objective of this study was to investigate the prevalence of hepatitis B (HB) and its correlation with epidemiological data obtained from the community. The studied population totaled 260 individuals with ages varying from 1 to 79 years (median 20). One hundred thirty-three (51.2%) were females and 127 (48.8%) were males. A high prevalence for anti-HBc was observed (42.7%), with present infection detected in 9.2% of the subjects who were also HB surface antigens (HBs Ag) positive; 27.3% were anti-HBc and anti-HBs reactive, and 6.2% had anti-HBc as only marker. The prevalence for anti-HBc was proportional to age, reaching its highest peak in age categories greater than 50. No serological marker was detected in children under the age of 2 years, however anti-HBc was present in 12 subjects with ages between 2 and 14 years, of these 8 (7.4%) were HBsAg positive. Among individuals over the age of 15 years, 99 were anti-HBc reactive, of these 16 (10.5%) were also HBsAg positive, thus suggesting an increased prevalence of HBV carriers among children and adolescents. The risk factors observed in this community that were significantly associated with anti-HBc positivity were age (over 20 years) and having an anti-HBc positive mother. Both HBeAg and anti-HBe were detected in 44.4% of the samples tested. HBsAg subtypes found in the studied population were adw2 (77.7%) and ayw2 (23.3%). While intrafamilial transmission was most likely responsible for HBV infection among children, other routes such as sexual contact might be considered for individuals with ages over 15 years.     

High Prevalence of HIV, HCV, HBV and Co-Infection and Associated Risk Factors among Injecting Drug Users in Yunnan Province, China

Objective

To estimate the prevalence of HIV, HCV, HBV and co-infection with 2 or 3 viruses and evaluate risk factors among injecting drug users (IDUs) in Yunnan province, China.

Methods

2080 IDUs were recruited from 5 regions of Yunnan Province, China to detect the infection status of HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV). Statistical analysis was performed to evaluate risk factors related to HIV, HCV and HBV infections.

Results

The infection rates among all participants were 25.5% for HIV, 77.7% for HCV, 19.2% for HBV, 15% for HIV/HCV, 0.3% for HIV/HBV, 7.8% for HCV/HBV and 7.1% for HIV/HCV/HBV. The prevalence of virus infection varied widely by region in Yunnan of China. Statistical analyses indicated that high prevalence of HIV and HCV among IDUs was positively associated with the duration of drug injection and sharing needles/syringes; besides, HCV infection was associated with the frequency of drug injection.

Conclusions

HIV, HCV, HBV infections and co-infections were still very prevalent among IDUs in Yunnan province because of drug use behaviors.