Hepatitis C Virus Exposure Research Articles

Improved Reflexive Testing Algorithm for Hepatitis C Infection Using Signal-to-Cutoff Ratios of a Hepatitis C Virus Antibody Assay

Chemiluminescence immunoassay (CIA) is used to detect hepatitis C virus (HCV) antibody status on the basis of signal-to-cutoff (S/Co) ratios. Positive results of antibody to HCV (anti-HCV) are followed by either recombinant immunoblot assay (RIBA) to confirm anti-HCV positivity or reverse transcription (RT)-PCR to detect viremia. We hypothesized that by analyzing S/Co ratios, we could determine a strategy to reduce unnecessary supplementary testing in our population. CIA was performed to screen for anti-HCV, and positive results were followed up with RT-PCR testing. Negative RT-PCR results were followed up with RIBA, whereas positive RT-PCR results were assumed to be RIBA positive. ROC curves were analyzed to determine the optimal S/Co ratios to predict HCV infection. We determined the S/Co ratios on 34 243 veteran patient samples. We found that with the CIA method 9.0% of patients had positive test results for anti-HCV. An S/Co ratio <3.0 ruled out active HCV infection and exposure with 100% negative predictive value. When the S/Co ratio was ≥20.0, positive predictive values were 98.5% compared with RIBA results, and 81.0% compared with RT-PCR results. RIBA is not necessary to confirm negative or positive CIA anti-HCV if the S/Co ratio is <3.0 or ≥20.0, respectively. To confirm HCV exposure, samples with an S/Co ratio between 3.0 and 19.9 should be followed up with RIBA unless PCR testing has been performed and the result is positive. Samples with an S/Co ratio ≥20.0 or positive RIBA results should be further tested by RT-PCR to determine HCV viremia status.

Covering the Cover

Covering the Cover

A Polymorphism in IL28B Distinguishes Exposed, Uninfected Individuals From Spontaneous Resolvers of HCV Infection

Background & AimsPolymorphisms in the interleukin-28B (IL28B) gene are associated with outcomes from infection with hepatitis C virus (HCV). However, the role of these polymorphisms in protecting injection drug users who are at high risk for HCV infection but do not have detectable antibodies against HCV or HCV RNA (exposed uninfected) has not been demonstrated. We investigated whether these individuals have the IL28B genotype rs12979860-CC, which protects some individuals against HCV infection.MethodsSeventy-four exposed uninfected individuals, 89 spontaneous resolvers, and 234 chronically infected individuals were genotyped to determine single nucleotide polymorphisms at IL28B.rs12979860.ResultsExposed, uninfected individuals had a significantly lower frequency of the protective genotype (rs12979860-CC) than anti-HCV-positive spontaneous resolvers (41.9% vs 69.7%, respectively; P = .0005; odds ratio [OR], 0.31; 95% confidence interval [CI]: 0.16–0.60) but a similar frequency to patients who were chronically infected (41.9% vs 43.6%, respectively; P = ns). However, exposed, uninfected individuals had a significantly higher frequency of homozygosity for killer cell immunoglobulin-like receptor 2DL3:group 1 HLA-C (KIR2DL3:HLA-C1) than those with chronic infection (31.1% vs 13.3%, respectively; P = .0008; OR, 2.95; 95% CI: 1.59–5.49). For patients who spontaneously resolved infection, IL28B and KIR:HLA protected, independently, against chronic HCV infection, based on logistic regression and synergy analyses (synergy factor, 1.3; 95% CI: 0.37–4.75; P synergy = .6).ConclusionsIL28B and KIR2DL3:HLA-C1 are independently associated with spontaneous resolution of viremia following HCV exposure. Resistance to HCV infection in exposed uninfected cases is associated with homozygosity for KIR2DL3:HLA-C1 but not the single nucleotide polymorphism IL28B.rs12979860. Uninfected individuals are therefore a distinct population from patients who spontaneously resolve HCV infection. Distinct, nonsynergistic innate immune mechanisms can determine outcomes of HCV exposure.

Loss of Virus-specific T-Cell Responses in HCV Exposed Uninfected Injection Drug Users With Drug Rehabilitation

Hepatitis C virus (HCV)-specific T lymphocyte responses have been demonstrated in peripheral blood from injection drug users (IDUs) persistently HCV antibody and RNA negative despite high-risk behavior. We have termed these apparently HCV resistant cases "Exposed Uninfecteds" (EUs), and have studied the evolution of T-cell responses to determine if they are protective in nature. Twenty-one EU cases were studied using a questionnaire to ascertain injecting behavior details. Peripheral blood mononuclear cells were isolated from whole blood and an interferon-gamma (IFN-γ) enzyme-linked immunosorbent spot (ELISPOT) assay used to detect T-cell responses to a panel of HCV proteins. EU cases were subdivided by injecting drug patterns into (1) cases in rehabilitation who stopped injecting, (2) prisoners (infrequent/noninjectors), and (3) cases who continued to inject. EUs continuing to inject had significantly stronger (P < .01) and more frequent (P < .05) HCV-specific IFN-γ ELISPOT responses than controls or noninjecting EUs. EUs in rehabilitation lost their T-cell responses during follow-up, while those continuing to inject maintained them. HCV-specific T-cell responses in EU cases wane within months of cessation of injection drug use. Maintenance of these T-cell responses appears to be dependent on continuing HCV exposure through injection drug use.

The Human Fetal Immune Response to Hepatitis C Virus Exposure in Utero

Although the rate of mother-to-child transmission of hepatitis C virus (HCV) is low, the effect of HCV exposure in utero on the fetal immune system is unknown. Umbilical cord blood was obtained from 7 neonates born to HCV-seropositive, HCV RNA-positive women and 8 neonates born to HCV-seronegative women. Cord blood mononuclear cells were analyzed by immunophenotyping and by intracellular cytokine staining after HCV-specific and polyclonal stimulation. Plasma was analyzed for anti-HCV immunoglobulin M (IgM), cytokine/granzyme concentrations, and indoleamine 2,3-dioxygenase (IDO) activity. HCV-exposed neonates had significantly lower levels of regulatory T cells expressing HLA-DR, lower CD4(+) and CD8(+) T cell activation, and lower plasma levels of pro-inflammatory markers than did controls. However, CD4(+) and CD8(+) T cells from HCV-exposed neonates had higher IFN-γ production in response to polyclonal stimulation than did T cells from controls. IDO activity was similar between groups. No HCV-specific T cell responses or anti-HCV IgM were detected in any neonates. HCV-exposed neonates showed a relative suppression of immune activation and pro-inflammatory markers, which was counterbalanced by an increased production capacity for IFN-γ. These results suggest that HCV encounters the fetal immune system in utero, and alters the balance between suppressive and pro-inflammatory responses.

Guidance for Occupational Health Services in Medical Centers

Guidance for Occupational Health Services in Medical Centers

Hepatitis C Virus and Lichen Planus

To explore the association between hepatitis C virus (HCV) and lichen planus (LP) by performing a meta-analysis of observational studies of the association. Data Sources Bibliographical searches were conducted in the MEDLINE, EMBASE, and China National Knowledge Infrastructure (CNKI) databases without any language limitations. Study Selection Studies were selected when the following criteria were met: the coexistence of a study group and a control group, the reliable and nonselective use of the reference standards for the diagnosis of LP and HCV, and the proportion of events (the prevalence of HCV in patients with LP or the prevalence of LP in patients with HCV). Data Extraction Three investigators independently assessed abstracts for relevant studies, and 2 investigators independently reviewed all eligible studies. Data Synthesis Sixty-three articles entailing 7 studies were included in the meta-analysis. For the primary outcome of prevalence of events, the meta-analysis showed that there existed an important association between HCV and LP. In the comparison of the prevalence of HCV exposure among patients with LP with that of control participants, the odds ratio (OR) was 5.4 (95% confidence interval [CI], 3.5-8.3); in the prevalence of LP among patients with HCV compared with the prevalence among control participants, the OR was 2.5 (95% CI, 2.0-3.1). The subgroup analyses with geographical stratification did not show a significant association in studies from South Asia (P = .21), Africa (P = .15), and North America (P = .09), and the subgroup analyses from stratification by LP type also did not show a significant association in the isolated cutaneous type (P = .17). When strict criteria were applied, the results of sensitivity analysis remained robust. Conclusion Hepatitis C virus infection is associated with a statistically significant risk for development of LP, suggesting that the presence of either HCV or certain types of LP may be used as a predictive marker of the other in certain geographical regions.

Hepatitis C virus (HCV)‐specific T‐cell responses among recombinant immunoblot assay‐3–indeterminate blood donors: a confirmatory evidence of HCV exposure

Blood donors are routinely screened for hepatitis C virus (HCV) infection. Some show weak anti-HCV responses, often restricted to a single antigen on confirmatory immunoblot (recombinant immunoblot assay [RIBA]) testing. The aim of this study was to investigate the extent to which such RIBA-indeterminate donors had previously been exposed to HCV. T-cell responses to HCV recombinant proteins (core, NS3, and NS3 helicase) were analyzed using an interferon-gamma (IFN-gamma) enzyme-linked immunospot (ELISpot) assay and quantification of cytokines in culture supernatants in 27 RIBA-indeterminate donors, 60 RIBA-confirmed donors (48 with and 12 without HCV RNA), and 30 RIBA-negative donors. HCV-specific T-cell responses were identified in 13 (48%) RIBA-indeterminate donors, 33 (55%) RIBA-confirmed donors, and 4 (13%) RIBA-negative controls (p = 0.008 and p < 0.001, respectively). The magnitude of the T-cell response among indeterminate donors was similar to that of RIBA-confirmed donors for all HCV antigens and the specificity of the ELISpot results was confirmed by antigen-specific cytokine production (interleukin-2 and IFN-gamma) in short-term culture supernatants. These findings confirm that approximately half of RIBA-indeterminate donors have resolved a previous HCV infection and suggest that ELISpot might be a useful tool to clarify the status of such donors and help in their counseling and management.

Phylogeography and molecular epidemiology of hepatitis C virus genotype 2 in Africa

Understanding the origin and nature of hepatitis C virus (HCV) genetic diversity is critical for improving treatment and vaccine design, and such diversity is the sole source of information about the virus' epidemic history prior to its identification 20 years ago. In this paper, we study the molecular epidemiology of HCV genotype 2 in its region of endemic origin, west and central Africa. Our analysis includes 56 new and highly diverse HCV isolates sampled from infected individuals in Guinea-Bissau. By combining phylogenetic, geographical and epidemiological information, we find a previously unappreciated geographical structure in the diversity of HCV genotype 2, pointing to a history of eastwards spatial spread from the west African coast to Cameroon that took place over several centuries. Molecular clock analysis dates the common ancestor of HCV in Guinea-Bissau to 1470 (1414-1582). The phylogenetic position of isolates from Madagascar and Martinique suggests a role for the historical slave trade in the global dissemination of HCV and of the epidemic subtypes 2a and 2c. Coalescent-based estimates of epidemic growth indicate a rapid 20th-century spread of HCV genotype 2 in Cameroon that is absent in Guinea-Bissau. We discuss this contrast in the context of possible parenteral HCV exposure during public-health campaigns undertaken during the colonial era.

NK cell Activation during Acute Hepatitis C Virus Infection (45.18)

Abstract Genetic studies have implicated the inhibitory natural killer (NK) cell receptor KIR2DL3 and its human leukocyte antigen C group 1 (HLA-C1) ligand in resolution of hepatitis C virus (HCV) infection but a functional correlation was not established. To examine the role of NK cells during acute HCV, we have analyzed longitudinally the phenotype and function of NK cells from a cohort of patients following HCV exposure. Three groups with different infectious outcome were identified: spontaneous resolvers (SR), chronic evolution (C) and exposed un-infected (EU) (n=10 in each group). We have observed increased NK cell cytotoxicity (%CD107a+) in all groups suggesting NK cell activation following exposure but no correlation was established with infectious outcome. Nevertheless, we observed decreased expression of KIR2DL1, associated with highest NK cell inhibition, in SR. Furthermore, the highest IFN-γ production was observed in KIR2DL3+ NK cells, the least inhibited population, in all groups. Our results suggest that NK cell direct cytotoxicity might not be implicated in HCV clearance but that less NK cell inhibition is more frequent in SR patients. These results confirm the important role of host genetic background in NK cell function and provides the first demonstration of such a functional correlation in an in vivo infection setting. Research support: The Dana Foundation, CIHR, FRSQ, NCRTP-HepC

The 1F7 idiotype is selectively expressed on CD5+ B cells and elevated in chronic hepatitis C virus infection

Antibodies against different chronic viruses, including hepatitis C virus (HCV), express a public cross-reactive idiotype (Id) designated as 1F7. The prominence of this Id may reflect selective engagement of B1 B cells by chronic pathogens. We investigated this by comparing 1F7 Id expression on CD5(+) and CD5(-) B cells, total IgG, total IgM and anti-HCV core antibodies in different HCV exposure settings. By flow cytometry, we observed a selective increase in 1F7 Id(+)CD5(+) B cells in chronic HCV infection. 1F7 Id levels in different immunoglobulin compartments were measured by enzyme-linked immunosorbent assay. 1F7 Id expression was prominent in anti-HCV core antibodies of approximately 90% of 141 HCV-exposed individuals tested. In the Canadian and Armenian study groups, participants who spontaneously cleared HCV infection had lower median 1F7 Id levels on total plasma IgG and anti-HCV core antibodies. Armenian spontaneous clearers, who were younger and more recently infected than their Canadian counterparts, also had had lower median 1F7 Id levels on total plasma IgM. Engagement by HCV of B-cell receptors within, or overlapping with the CD5(+) B1 B-cell repertoire is reflected in the production of 1F7 Id(+) anti-HCV antibodies and expansion of 1F7 Id(+)CD5(+) B cells. Higher 1F7 Id expression levels are associated with chronic infection.

Markers and risk factors for HCV, HBV and HIV in a network of injecting drug users in Melbourne, Australia

Current injecting drug users (IDU) in major street drug markets within greater Melbourne were recruited to a longitudinal study on blood borne viruses. Here we investigated risk factors for hepatitis C virus (HCV), hepatitis B virus (HBV) and HIV infection in these IDU at the time of their recruitment. Three hundred and eighty-two IDU completed detailed questionnaires on their drug use and risk behaviours, and provided blood samples for serology testing. These data were analysed using univariate and multivariate techniques. The overall prevalence of exposure to HCV, HBV and HIV was estimated at 70%, 34% and <1%, respectively. Independent predictors of HCV exposure were history of imprisonment (RR 1.34, 95% CI 1.19-1.52), use of someone else's needle or syringe (RR 1.23, 95% CI 1.07-1.42), >7.6years length of time injecting (RR 1.21, 95% CI 1.07-1.37), and originating from Vietnam (RR 1.12, 95% CI 1.07-1.18). Independent predictors of HBV exposure were HCV exposure (RR 2.15, 95% CI 1.35-3.43), >7.6years length of time injecting (RR 1.57, 95% CI 1.17-2.13) and originating from outside Australia (RR 1.60, 95% CI 1.22-2.10). Neither prison- nor community-applied tattoos predicted HCV or HBV exposure. Up to 31% of IDU who injected for 1year or less were HCV antibody positive, as were 53% of those who injected for 2years or less. Ongoing engagement with young IDU, through the provision of harm reduction education and resources, is critical if we are to address blood borne viral infections and other health and social harms associated with injecting drug use.

Risikofaktorer for hepatitt C-smitte blant sprøytemisbrukere

Hepatitis C virus (HCV) infection is common among injecting drug users. The aims of this study were to assess the prevalence of risk behaviour and its association with HCV infection. All users of the needle exchange program in Oslo, within a given time period, were eligible for inclusion in this cross-sectional study; 327 chose to participate. The users were asked about type of drug use and risk behaviour for HCV exposure in a structured interview. Sera were drawn and tested for anti HCV (EIA-3) and HCV RNA (in- house PCR). The prevalence of HCV RNA was 51 % and 81 % had anti-HCV. A multivariate analysis revealed positive associations between anti-HCV positive status and age < 20 years at first injection, > 5 years of drug use, age > 34 years, sharing of syringes, injecting drug use while imprisoned, back-loading and use of heroin. One in five users with anti-HCV reported to never have shared syringes. However, sharing of drug paraphernalia other than needles was not associated with anti-HCV. Sharing of needles the last four weeks before the interview was more common among those living with a partner than those who lived alone. Most injecting drug users in Oslo have been exposed to HCV (anti HCV+) and half of them have developed chronic infection (HCV RNA+). HCV was associated with back-loading and sharing of syringes - especially during incarceration. Sharing of injection paraphernalia was not associated with being anti HCV positive.

Hepatitis C virus-specific T-cell immune responses in seronegative injection drug users.

T-cell responses to hepatitis C virus (HCV) antigens have been reported in high-risk HCV seronegative persons, suggesting that an effective cellular immune response might be able to clear infection without the development of antibodies. Such findings, however, could be explained by waning antibody or cross-reactivity to other antigens. To address these issues, we evaluated HCV-specific T-cell responses in 26 young (age 18-33 years) aviremic, seronegative injection drug users (IDUs) (median duration of injection, 6 years) by interferon-gamma enzyme-linked immunospot (ELISpot) assay using 429 overlapping HCV peptides pooled in 21 mixes. Seventeen aviremic, seropositive IDUs (spontaneous resolvers) and 15 healthy people were used as positive and negative controls, respectively. The percentage of patients with HCV-specific cellular immune responses was similar in seronegative and seropositive aviremic IDUs (46%vs 59%, P = 0.4), while these responses were not detected in any of the negative controls. Among the seronegative IDUs, six (23%) had intermediate to very strong responses to 10-20 peptide mixes and another six (23%) had moderately strong responses for two to six mixes. The 12 seronegative IDUs with HCV-specific T-cell responses had higher demographical and behavioural risk profiles than the 14 IDUs without T-cell responses (estimated risk of HCV infection, 0.47 vs 0.26, P < 0.01). In conclusion, HCV-specific T-cell responses are common among high-risk, seronegative IDUs. The responses are broad and are associated with risk factors for HCV exposure, suggesting that they reflect true exposure to HCV in seronegative persons.

Hepatitis C Virus (HCV)–Specific T Cell Responses in Injection Drug Users with Apparent Resistance to HCV Infection

Injection drug users (IDUs) are at risk of acquiring hepatitis C virus (HCV) infection. We have identified a cohort of long-term IDUs who remain uninfected by HCV despite high-risk behavior. We have categorized these subjects as "exposed uninfected" and have sought immunological correlates with this apparent resistance. We studied 40 exposed uninfected subjects testing negative for both HCV antibody and HCV RNA. Details of injection behavior were ascertained by questionnaire. In vitro interferon (IFN)-gamma production by T cells in response to HCV proteins (core, E1, NS3, NS4, and NS5) was quantified by enzyme-linked immunospot assay, and findings were compared with those in 21 healthy control subjects. All exposed uninfected subjects reported sharing needles or other injection paraphernalia on multiple occasions. The mean duration of injecting was 9.3 years (range, 0.5-26 years), with a median estimated number of injection episodes of 8760. IFN-gamma production in response to HCV proteins was found in 23 (58%) of 40 exposed uninfected subjects versus 4 (19%) of 21 control subjects (P = .004), with 14 exposed uninfected subjects responding to multiple antigens, compared with none of the control subjects (P = .001). The majority of long-term IDUs who remain uninfected by HCV despite their high-risk behavior have HCV-specific T cell responses. These responses were frequently found for multiple HCV proteins, making cross-reactivity to other homologous antigens unlikely. These responses may represent an immunological footprint of HCV exposure that has not resulted in viremia or HCV antibody seroconversion. The potential role played by these responses in protection from HCV infection is of clinical importance.

Modelling and calibration of the hepatitis C epidemic in Australia

Hepatitis C virus (HCV) infection in Australia is predominantly transmitted through injecting drug use. A reduction in the heroin supply in Australia in late 2000 and early 2001 may have impacted the number of injecting drug users (IDUs) and the number of new hepatitis C infections. This paper updates estimates of HCV incidence between 1960 and 2005 and models long-term sequelae from infection. Outcomes among those with HCV were also recently assessed in a linkage study assessing cancer and causes of death following HCV diagnosis in New South Wales. Linkage study outcomes have been used here to calibrate modelled outcomes. Mathematical models were used to estimate HCV incidence among IDUs, migrants to Australia from high HCV-prevalence countries, and other HCV exposure groups. Recent trends in numbers of IDUs were based on indicators of injecting drug use. A natural history of HCV model was applied to estimate the prevalence of HCV in the population. Model predicted endpoints that were calibrated against the NSW linkage data over the period 1995-2002 were: (i) incident hepatocellular carcinoma (HCC); (ii) opioid overdose deaths; (iii) liver-related deaths; and (iv) all-cause mortality. Modelled estimates and the linkage data show reasonably good calibration for HCC cases and all-cause mortality. The estimated HCC incidence was increased from 70 cases in 1995 to 100 cases in 2002. All-cause mortality estimated at 1000 in 1995 increased to 1600 in 2002. Comparison of annual opioid deaths shows some agreement. However, the models underestimate the rate of increase observed between 1995 and 1999 and do not entirely capture the rapid decrease in overdose deaths from 2000 onwards. The linkage data showed a peak of overdose deaths at 430 in 1999 compared to 320 estimated by the models. Comparison of observed liver deaths with the modelled numbers showed poor agreement. A good agreement would require an increase in liver deaths from the assumed 2 to 5% per annum following cirrhosis in the models. Mathematical models suggest that HCV incidence decreased from a peak of 14,000 infections in 1999 to 9700 infections in 2005, largely attributable to a reduction in injecting drug use. The poor agreement between projected and linked liver deaths could reflect differing coding of causes of deaths, underestimates of the numbers of people with cirrhosis following HCV, or underestimates of rates of liver death following cirrhosis. The reasonably good agreement between most of the modelled estimates with observed linkage data provides some support for the assumptions used in the models.

Acute, Clinically Evident Hepatitis C Virus Infection and Liver Injury

Purpose: Clinically evident acute (or recent) hepatitis C virus (HCV) infection and liver injury is uncommon, in contrast to chronic HCV infection and associated liver disease. However, the clinical and laboratory features of overt recent HCV infection are not dissimilar to other etiologies of acute hepatitis, i.e. fatigue, anorexia, pale stools and dark urine; serum aminotransferase concentrations are typically elevated significantly. Therefore, because clinically overt acute HCV infection is uncommon and alternative diagnoses demand consideration, e.g. autoimmune hepatitis (AIH), liver biopsy may be undertaken. A recent report drew attention to the spectrum of observed histologic abnormalities, such as those concerning for large bile duct occlusion. Methods: We describe five patients with what we believe was clinically evident acute HCV infection and liver injury, all of whom required and underwent liver biopsy on clinical grounds. Results: Five adult patients (two men; median age 41 years [range 19–47]) presented for further evaluation of acute severe liver injury, either without (two patients) or with symptoms – malaise, anorexia, nausea, abdominal pain, pale stools and dark urine. The means of recent HCV exposure was as follows: sexual (two), intranasal (two), and intravenous (one). Pertinent data are contained in the table. Alternative causes of acute severe liver injury (viral, autoimmune, drug-induced, metabolic and alcoholic) were excluded as far as possible by history-taking and laboratory testing. However, because liver injury was so marked, and in three patients alternative or additional explanations existed (Wilson's disease, AIH) liver biopsy was undertaken. Unlike classic descriptions of morphologic changes in acute viral hepatitis, namely lobular hepatocyte swelling/ballooning and acidophil necrosis, pigment-laden macrophages, and/or canalicular cholestasis (all five biopsies revealed these changes), two of the biopsy specimens demonstrated portal tract expansion by edema, with many neutrophils and evidence of bile duct injury. Chronic inflammation was minimal. This raised concern for a primary biliary process, e.g. large duct obstruction. Furthermore, one of these two specimens revealed numerous portal eosinophils concerning for drug reaction. Conclusion: All five patients had laboratory evidence of acute severe liver injury. Symptomatic patients had lower serum albumin, but higher total serum bilirubin and alanine aminotransferase (ALT) concentrations than those without symptoms. Moreover, this difference distinguished those patients with histological changes concerning for an underlying biliary process from those who did not in two of three cases. Timing between infection and liver biopsy might explain these differences.Table

High prevalence of hepatitis C virus infection among noninjecting drug users: association with sharing the inhalation implements of crack

Most of the prevalent cases of hepatitis C virus (HCV) infection are attributable to intravenous drug using. However, a substantial number of individuals, particularly noninjecting drug users (NIDU), report no identifiable source of HCV exposure. This may be interpreted as inaccurate reporting of past intravenous exposure or as the presence of an unidentified source of HCV infection. Because of this, we evaluated the prevalence of and factors associated with HCV infection among NIDU. One hundred and eighty-two individuals who were attended from 2003 to 2004 in a drug addiction facility because of noninjecting drug use were included. HCV infection was detected in 23 (12.6%) participants. Sharing the inhalation tube of crack cocaine [adjusted odds ratio (AOR) 3.6, 95% confidence interval (CI) 1.3-9.8, P=0.01], presence of tattoos (AOR 3.5, 95% CI 1.3-9.1, P=0.02) and age >or=34 years (AOR 3.9, 95% CI 1.3-11.6, P=0.01) 3.9 were independently associated with HCV infection. The prevalence of HCV infection in NIDU is higher than in general population. HCV infection is more likely among older drug users, those with tattoos and crack cocaine users that share the inhalation implements.

Noninjection drug use: an under‐appreciated risk factor for hepatitis C virus transmission

Noninjection drug use: an under‐appreciated risk factor for hepatitis C virus transmission

Investigation of Putative Multisubtype Hepatitis C Virus Infections In Vivo by Heteroduplex Mobility Analysis of Core/Envelope Subgenomes

The frequency that multiple different subtypes of hepatitis C virus (HCV) simultaneously infect a given individual is controversial. To address this question, heteroduplex mobility analysis (HMA) of portions of the HCV core and envelope 1 region was optimized for sensitive and specific detection of mixtures of HCV genomes of different genotype or subtype. Using the standard HCV genotyping approach of 5'-untranslated region (UTR) analysis, 28 of 374 (7.5%) chronic hepatitis C research subjects were classified as having either multiple-subtype HCV infections (n = 21) or switching HCV subtypes over time (n = 7), the latter pattern implying viral superinfection. Upon retesting of specimens by HMA, 25 of 28 multiple-subtype results could not be reproduced. All three patients with positive results were injection drug users with potential multiple HCV exposures. To address the hypothesis of tissue sequestration of multiple-subtype HCV infections, liver (n = 22), peripheral blood mononuclear cell (n = 13), perihepatic lymph node (n = 16), and serum (n = 19) specimens from 23 subjects with end-stage hepatitis C were collected and analyzed by the HMA technique. Whereas 5'-UTR results implicated mixed-subtype HCV infections in 2 subjects, HMA testing revealed no evidence of a second HCV subtype in any tissue compartment (0 of 70 compartments [0%]) or within any given subject (0 of 23 subjects [0%]). In summary, a large proportion of mixed-genotype and switching-genotype patterns generated by 5'-UTR analysis were not reproducible using the HMA approach, emphasizing the need for additional study.