Use of phylogenetic analysis of hepatitis C virus (HCV) hypervariable region 1 sequences to trace an outbreak of HCV in an autodialysis unit

Updated Pathway to Micro-elimination of Hepatitis C Virus in the Hemodialysis Population

Chronic hepatitis C virus (HCV) infection continues to be transmitted to hemodialysis (HD) patients within HD facilities globally. The goal of the World Health Organization to micro-eliminate HCV infection from the HD population by the year 2030 is not on target to be achieved. Obstacles to eliminate HCV in HD settings remain daunting due to a complex system created by a confluence of guidelines, legislation, regulation, and economics. HCV prevalence remains high and seroconversion continues among the HD patient population globally as a result of the HD procedure. Preventive strategies that effectively prevent HCV transmission, treatment-as-prevention, and rapid referral to treatment balanced with kidney transplant candidacy should be added to the current universal precautions approach. A safer system must be designed before HCV transmission can be halted and eliminated from the HD population.

Pathophysiology and Treatment of Hepatitis B and C Infections in Patients With End-Stage Renal Disease

An in-depth understanding of viral hepatitis is important to the care of patients with end-stage renal disease undergoing hemodialysis. Both hepatitis B and C viruses are acquired through hematogenous spread and can lead to horizontal transmission. Concurrent hepatic and renal injuries have ominous outcomes with significant morbidity. Hepatitis B incidence has decreased through practices including vaccination of nonimmune individuals and isolation of patients with the disease. The pathogenesis of hepatitis B leads to various symptoms and serologic changes with unique temporal associations dictating an acute or chronic presentation. Chronic hepatitis B develops when there is persistence of surface antigen for more than 6 months. Occult hepatitis B is an enigmatic form of the chronic disease where viral DNA is present despite the patient remaining seronegative. Nucleoside analogs are used as a treatment for individuals with hepatitis B who have comorbid CKD; however, the mainstay of infection control relies on immunization. Hepatitis C, an RNA virus, has increased in prevalence. Strict universal precautions with sound infection-control practices are important to prevent seroconversion. Recent therapeutic advances involving the development of direct-acting antiviral agents have broadened treatment options for patients with renal impairment and hepatitis C, offering the potential for a definitive cure. Controversy on the timeliness of treatment for transplant options has also risen with the advent of these newer therapies. We review the epidemiology, pathophysiology, and updates in treatment of these viral entities as they relate to the hemodialysis population.

Transmission of hepatitis C virus infection in hemodialysis: Current concepts

A variety of epidemiological data provides evidence for the occurrence of nosocomial transmission of hepatitis C virus (HCV) infection to hemodialysis (HD) patients. The most important factor implicated in HCV transmission between patients treated in the same dialysis unit is cross-contamination from supplies and surfaces as a result of failure of staff to follow infection control procedures. Parts of the HCV genome are highly variable and lend themselves to fingerprinting of each isolate using nucleic acid testing (NAT) and sequencing. This approach has permitted investigation of possible transmission routes within HD units. A systematic review of molecular virology papers revealed transmission of HCV via internal fluid pathways of the dialysis machines in a minority of reports only. Dialyzer reuse was not identified as a risk factor for HCV acquisition in multicenter databases. No randomized controlled trials exist on the impact of isolation on the risk of transmission of HCV to hemodialysis patients. A Belgian prospective multicenter study showed a reduction from 1.4% to 0% in the annual incidence of seroconversion for HCV without any isolation measures, by implementation of strict infection control procedures designed to prevent transmission of blood-borne pathogens, including HCV. However, an isolation policy for HCV-infected dialysis patients should be considered in dialysis units where nosocomial transmission of HCV persists despite reinforcement and audit of hygienic precautions for hemodialysis. Routine audit precautions (general and for dialysis machines) are recommended on a regular basis within HD units.

Investigation of a Case of Genotype 5a Hepatitis C Virus Transmission in a French Hemodialysis Unit Using Epidemiologic Data and Deep Sequencing

BACKGROUND Hepatitis C virus (HCV) is a major cause of chronic liver disease worldwide. A patient was recently found to be HCV seropositive during hemodialysis follow-up. OBJECTIVE To determine whether nosocomial transmission had occurred and which viral populations were transmitted. DESIGN HCV transmission case. SETTING A dialysis unit in a French hospital. METHODS Molecular and epidemiologic investigations were conducted to determine whether 2 cases were related. Risk analysis and auditing procedures were performed to determine the transmission pathway(s). RESULTS Sequence analyses of the NS5b region revealed a 5a genotype in the newly infected patient. Epidemiologic investigations suggested that a highly viremic genotype 5a HCV-infected patient who underwent dialysis in the same unit was the source of the infection. Phylogenetic analysis of NS5b and hypervariable region-1 sequences revealed a genetically related virus (>99.9% nucleotide identity). Deep sequencing of hypervariable region-1 indicated that HCV quasispecies were found in the source whereas a single hypervariable region-1 HCV variant was found in the newly infected patient, and that this was identical to the major variant identified in the source patient. Risk analysis and auditing procedures were performed to determine the transmission pathway(s). Nosocomial patient-to-patient transmission via healthcare workers' hands was the most likely explanation. In our dialysis unit, this unique incident led to the adjustment of infection control policy. CONCLUSIONS The data support transmission of a unique variant from a source with a high viral load and genetic diversity. This investigation also underlines the need to periodically evaluate prevention and control practices.

Transmission of hepatitis C virus in dialysis units: a systematic review of reports on outbreaks

BACKGROUND

Hepatitis C virus (HCV) outbreaks among patients on hemodialysis are still an important health concern all over the world.

AIMS

We performed a systematic review of reports on HCV outbreaks within dialysis units of developed and less-developed countries (between 1992 and 2015) to evaluate risk factors and practices associated with patient-to-patient transmission of HCV in this setting.

METHODS

The research was performed using the PubMed Database and the Outbreak Database; studies were selected according to the PRISMA algorithm. Inclusion criteria were established before the papers were retrieved in order to avoid selection biases.

RESULTS

36 papers reported on 45 outbreaks that involved 335 unique patients on maintenance hemodialysis; no fatal cases were detected. Nosocomial transmission of HCV was confirmed by phylogenetic analysis in most (n=31; 69%) reports. Sharing contaminated hemodialysis machines and multidose vials (heparin or saline solution) was suggested responsible for HCV transmission in 8 (18%) and 6 (13%) outbreaks, respectively. Breaches in environmental cleaning and disinfection practices, and failures in medication preparation and administration practices was considered in 29 (65%) outbreaks; however, the exact mechanism of transmission of HCV could not be ascertained in each facility where an outbreak occurred.

CONCLUSIONS

Our systematic review of reports on hepatitis C virus outbreaks shows that, although the full extent of HCV transmission in dialysis units is unknown, outbreaks continue to occur. Full compliance to standard/specific infection control procedures and routine serologic screening for HCV antibody play a pivotal role for preventing the transmission of HCV within hemodialysis units.

Natural evolution of hepatitis C virus infection in hemodialysis Tunisian patients and CTLA-4 SNP's

AIM: To analyze the polymorphisms of CTLA-4 gene involved in the response against hepatitis C virus (HCV) infection.

METHODS: We recruited 500 hemodialysed patients from several hemodialysis centers, all HCV-antibody positive, spread over different regions of Tunisia, as part of a national survey in 2008 conducted in the laboratory of immunology at the Charles Nicolle hospital Tunisia, classified into two groups G1 (PCR+) and G2 (PCR-) according to the presence or absence of viral RNA. Of these patients, 307 were followed prospectively on a viral molecular level over a period from 2002 to 2008, divided into two groups based on the persistence and viral clearance. PCR-RFLP was performed for the analysis of SNPs (+49) A/G and (+6230) G/A CTLA-4 for these 500 patients and 358 healthy controls.

RESULTS: Analysis of clinical and virological characteristics of our cohort suggests a nosocomial infection in our hemodialysed patients with transfusion history as a primary risk factor and a predominance of genotype 1b. The haplotype analysis revealed an increase of frequencies of GG (+49)/(CT60) CTLA-4 in the entire patients group compared to controls (P = 0.0036 and OR = 1.42; 95%CI: 1.12-1.79, respectively). This haplotype is therefore associated with susceptibility to HCV infection.

CONCLUSION: Our study suggests a possible role of CTLA-4 polymorphisms in the outcome of HCV infection in the Tunisian hemodialysed population.

Hepatitis C virus diversification in Argentina: comparative analysis between the large city of Buenos Aires and the small rural town of O'Brien

Background

The estimated prevalence of HCV infection in Argentina is around 2%. However, higher rates of infection have been described in population studies of small urban and rural communities. The aim of this work was to compare the origin and diversification of HCV-1b in samples from two different epidemiological scenarios: Buenos Aires, a large cosmopolitan city, and O'Brien, a small rural town with a high prevalence of HCV infection.

Patients and Methods

The E1/E2 and NS5B regions of the viral genome from 83 patients infected with HCV-1b were sequenced. Phylogenetic analysis and Bayesian Coalescent methods were used to study the origin and diversification of HCV-1b in both patient populations.

Results

Samples from Buenos Aires showed a polyphyletic behavior with a t_MRCA around 1887–1900 and a time of spread of infection approximately 60 years ago. In contrast, samples from ÓBrien showed a monophyletic behavior with a t_MRCA around 1950–1960 and a time of spread of infection more recent than in Buenos Aires, around 20–30 years ago.

Conclusion

Phylogenetic and coalescence analysis revealed a different behavior in the epidemiological histories of Buenos Aires and ÓBrien. HCV infection in Buenos Aires shows a polyphyletic behavior and an exponential growth in two phases, whereas that in O'Brien shows a monophyletic cluster and an exponential growth in one single step with a more recent t_MRCA. The polyphyletic origin and the probability of encountering susceptible individuals in a large cosmopolitan city like Buenos Aires are in agreement with a longer period of expansion. In contrast, in less populated areas such as O'Brien, the chances of HCV transmission are strongly restricted. Furthermore, the monophyletic character and the most recent time of emergence suggest that different HCV-1b ancestors (variants) that were in expansion in Buenos Aires had the opportunity to colonize and expand in O’Brien.

Phylogenetic analysis of isolated HCV strains from tunisian hemodialysis patients

The present study describes the strains of hepatitis C virus (HCV) isolated from Tunisian hemodialysis patients. Thirty-three HCV strains isolated from different dialysis centers in Tunis City were amplified by RT-PCR in a region of the NS5b gene, genotyped by sequencing, and compared to international sequences by phylogenetic analysis. The phylogenetic tree showed that 16 HCV isolates have been identified as subtype 4k (48.5%), 7 as unspecified HCV-4 subtype (21.2%), 5 as subtype 4a et 1b (each 15.2%). The analysis of this tree revealed that the HCV-1b strains were closely related to Anglo-Saxon and European isolates, while the HCV-4 isolates are genetically similar to Egyptian and African strains. Phylogenic analysis of 33 Tunisian isolates with international HCV strains on a region of the NS5b gene demonstrated that the subtype 4k submerged the Tunis city and a new subtype of HCV4 seems to be suspect in this area.

Infection control guidelines for prevention of health care-associated transmission of hepatitis B and C viruses

Viral hepatitis was first identified as an occupational hazard for health care workers more than 60 years ago. For the past few decades, hepatitis B has been one of the most significant occupational infectious risks for health care providers. With the increasing prevalence of hepatitis C infections around the world, occupational transmission of this flavivirus from infected patients to their providers has also become a significant concern. Several factors influence the risk for occupational blood-borne hepatitis infection among health care providers, among them: the prevalence of infection among the population served, the infection status of the patients to whom workers are exposed (ie, the source patient's circulating viral burden), the types and frequencies of parenteral and mucosal exposures to blood and blood-containing body fluids, and whether the patient or provider has been immunized with the hepatitis B vaccine. This article reviews patient-to-provider, patient-to-patient, and provider-to-patient transmission of hepatitis B and C in the health care setting. Current prevention strategies, precautions, and guidelines are discussed.

Molecular epidemiology of health care-associated transmission of hepatitis B and C viruses

The term "molecular epidemiology" has been ascribed to a host of different activities that involve gene-sequence analysis. Some examples of molecular epidemiology include modeling exercises of phylogenetic trees to reconstruct epidemics; studies of the evolution of hepatitis C virus (HCV); rates of nucleotide substitution in the hepatitis B virus (HBV) surface (S) gene; variations in the core promoter/pre-core/core region of HBV genotype C from different sources; analysis of HBV surface antigen mutations; molecular clock analyses of the short-term evolution of HCV; and analyses of clades and surface antigen polymorphisms of HBV. However, for most epidemiologists molecular epidemiology of viral hepatitis usually refers to studies of gene-sequence homology in HBV or HCV recovered from people in the community or an institution that allows better characterization and assignment of related clusters of infection.

High prevalence of hepatitis C virus genotype 1b infection in a small town of Argentina. Phylogenetic and Bayesian coalescent analysis

Previous studies in Argentina have documented a general prevalence of Hepatitis C Virus (HCV) infection close to 2%. In addition, a high prevalence of HCV has been recently reported in different Argentinean small rural communities. In this work, we performed a study aimed at analyzing the origins and diversification patterns of an HCV outbreak in Wheelwright, a small rural town located in Santa Fe province (Argentina).A total of 89 out of 1814 blood samples collected from people living in Wheelwright, were positive for HCV infection. The highest prevalence (4.9%) was observed in people older than 50 years, with the highest level for the group aged between 70-79 years (22%). The RFLP analyses showed that 91% of the positive samples belonged to the HCV-1b genotype. The E1/E2 and NS5B genes were sequenced, and their phylogenetic analysis showed that the HCV-1b sequences from Wheelwright were monophyletic. Bayesian coalescent-based methods were used to estimate substitution rates and time of the most recent common ancestor (tMRCA). The mean estimated substitution rates and the tMRCA for E1/E2 with and without HVR1 and NS5B were 7.41E-03 s/s/y and 61 years, 5.05E-03 s/s/y and 58 years and 3.24E-03 s/s/y and 53 years, respectively. In summary, the tMRCA values, the demographic model with constant population size, and the fact that the highest prevalence of infection was observed in elder people support the hypothesis that the HCV-1b introduction in Wheelwright initially occurred at least five decades ago and that the early epidemic was characterized by a fast rate of virus transmission. The epidemic seems to have been controlled later on down to the standard transmission rates observed elsewhere.

Determinant roles of environmental contamination and noncompliance with standard precautions in the risk of hepatitis C virus transmission in a hemodialysis unit

BACKGROUND

Nosocomial transmission is the second most frequent cause of hepatitis C virus (HCV) infection. A prospective observational study was conducted to assess the roles of environmental contamination and noncompliance with standard precautions in HCV cross-transmission in a hemodialysis unit.

METHODS

Patients undergoing chronic hemodialysis in a French university hospital unit were systematically screened, revealing 2 sporadic cases of HCV transmission. An investigation was launched to determine whether the patients were infected in the hemodialysis unit and the possible roles of environmental contamination and noncompliance with standard precautions. We examined possible relationships among new cases of HCV infection, environmental contamination by blood and HCV RNA, and compliance with guidelines on hand hygiene and glove use.

RESULTS

Two patients experienced seroconversion to HCV during the study period. Phylogenetic analyses showed that 1 of these patients was infected with the same strain as that affecting a chronically infected patient also treated in the unit. Of 740 environmental surface samples, 82 (11%) contained hemoglobin; 6 (7%) of those contained HCV RNA. The rate of compliance with hand hygiene was 37% (95% confidence interval, 35%-39%), and gloves were immediately removed after patient care in 33% (95% confidence interval, 29%-37%) of cases. A low ratio of nurses to patients and poor hand hygiene were independent predictors of the presence of hemoglobin on environmental surfaces.

CONCLUSION

Blood-contaminated surfaces may be a source of HCV cross-transmission in a hemodialysis unit. Strict compliance with hand hygiene and glove use and strict organization of care procedures are needed to reduce the risk of HCV cross-transmission among patients undergoing hemodialysis.

A cost-identification analysis of screening and surveillance of hepatitis C infection in a prospective cohort of dialysis patients

The Center for Disease Control and Prevention (CDC) recommends screening and surveillance of dialysis patients for hepatitis C virus (HCV), but there are limited data on the real life performance of confirmatory tests. We performed a cost-identification analysis of CDC recommendations using a large database of dialysis subjects. Screening and surveillance were performed according to CDC guidelines: enzyme immunoassay (EIA) testing upon entry then biannual surveillance. All positive EIA tests were confirmed by either polymerase chain reaction (PCR) or radioimmunoblot assay (RIBA). A total of 12,563 patients were tested from 1997 to 2004. By EIA, the prevalence of HCV was 8.4% and annual incidence was 0.96%. The prevalence after confirmation by RIBA and PCR was 5.8% and 4.8%, respectively. The annual incidence of hepatitis C confirmed by RIBA and PCR was 0.13% and 0.084%, respectively. Using Medicare reimbursement, the cost to screen and confirm one case of hepatitis C by RIBA was $372 versus $503 by PCR. However, the cost to identify an incident infection increased to $30,594 by RIBA and $48,622 by PCR. In the sensitivity analysis, the cost of identifying incident HCV infection dropped by 50% when the surveillance interval was extended to 1 year or when seroconversion rates for EIA occurred at 2%. Due to high surveillance cost, further studies are necessary to determine optimal intervals and settings.

Hepatitis C in hemodialysis patients: current global magnitude, natural history, diagnostic difficulties, and preventive measures

Hepatitis C virus (HCV) infection is a significant cause of morbidity and mortality in hemodialysis (HD) patients. The reported prevalence of HCV among the HD population has varied greatly from 1.9 to 84.6% in different countries in recent years. The length of time on HD is generally believed to be associated with HCV acquisition in HD subjects. Nevertheless, several recent reports failed to recognize any significant role of blood transfusion. Although there are some considerations about the accuracy of serologic testing in detecting HCV in HD patients, the accumulated data in this review suggest the false-negativity rate to be not more than 1.66% (153/9,220). Therefore, substituting virologic for serologic testing in the routine diagnosis of HCV infection in HD patients seems unreasonable. Several phylogenetic analyzes of viral isolates suggested nosocomial patient-to-patient transmission of HCV among HD patients for which the main potential source is believed to be contaminated hands and articles. However, isolation of HCV-infected HD patients and use of dedicated machines are currently unjustified while strict adherence to universal precautions seems to be enough to control disease spread in HD units. The present article is an update on epidemiological and clinical features of HCV in HD population.

The epidemiology and virology of hepatitis C virus genotype 5 in central France

BACKGROUND

We previously reported high prevalence of hepatitis C virus genotype 5a (HCV 5) (14%) in Central France.

AIM

To identify the risk factors associated with HCV5 infection and to characterize local HCV5 lineages.

METHOD

A case-control study and phylogenetic analysis were conducted.

RESULTS

In all, 131 HCV5 and 343 HCV non 5 infected patients were enrolled. No HCV5 patient was born in sub-Saharan Africa and only two were injection drug user. HCV5 contamination was associated with living in a rural area called Vic le Comte (VLC) in non-transfused patients (OR = 17.7), with transfusion in patients living outside VLC (OR = 3.8) and with receiving injections in patients from VLC (OR = 3.1). More than 80% of the patients from outside VLC were contaminated by transfusion and those from VLC mainly by an iatrogenic factor - injections performed before 1972 by the local physician. Phylogenetic analysis of HCV5 isolates evidenced no distinct genetic cluster, but close relationships between the isolates of spouse pairs and between blood donors and recipients.

CONCLUSIONS

Our results suggest that HCV5 spread in our district by iatrogenic route before 1972 and then via transfusion to the whole district. Collaborative studies are underway to study viral sequences from different parts of Africa and Europe to estimate the origin of our HCV 5a strains.

Molecular characterization of a variant rhinovirus from an outbreak associated with uncommonly high mortality

BACKGROUND

Human rhinoviruses (HRVs) are the most frequent cause of acute upper respiratory tract infection, however, they are also known to replicate in the lower respiratory tract and associate with more severe respiratory illnesses. An outbreak of HRV occurred in a long-term facility in Santa Cruz, California with unusually high morbidity and mortality.

OBJECTIVES

To identify viral characteristics associated with this unique outbreak, genetic relationships between these clinical isolates (SCRVs) and prototype strains of rhinovirus were investigated.

STUDY DESIGN

Sequence homology and phylogenetic analyses of the SCRV VP4/VP2 region were performed in conjunction with all HRV prototypes. Due to the importance of the 5'noncoding region (NCR) and the structural genes to viral replication and host immune responses, respectively, we focused on a segment of the HRV genome which includes these regions. Molecular models of SCRV were also assessed.

RESULTS

SCRV showed closest similarity to HRV82 with some divergence from the prototype. Amino acid differences were concentrated within predicted neutralization epitopes within VP2, VP3 and VP1.

CONCLUSION

Sequence analyses and differences in cell culture growth characteristics suggest that this virus is a variant of HRV which has distinctive properties from its respective prototype strain.

Determining the source of nosocomial transmission in hemodialysis units in Tunisia by sequencing NS5B and E2 sequences of HCV

Hepatitis C virus infection is a significant problem in hemodialysis units. HCV is very variable genetically with six genotypes. Clinical and epidemiological investigation of a new infection requires the determination of both the genotype and the strain of the HCV involved. A prospective, epidemiologic study of 395 dialysis patients in Tunisia was conducted from November 2001 to November 2003 to identify the source of nosocomial transmission using phylogenetic analysis of NS5b and E2 sequences. Hepatitis C infection was diagnosed by screening for anti-HCV antibodies and HCV RNA in sera using third generation ELISA and a qualitative RT-PCR assay. HCV strains were genotyped by sequencing the NS5b region. The genetic relatedness of the HCV strains was studied by sequencing the NS5b and the HVR-1 regions of the HCV genome. Two de novo cases of HCV infection were detected during the follow-up. One of them has been described previously. The case described in this study occurred in a center in which 12 patients were already infected with HCV strains belonging to genotypes 1b (n = 8) and 1a (n = 4). Phylogenetic analysis of the NS5b region from the HCV strains circulating in this center disclosed four clusters, confirmed by analysis of the HVR-1 region, providing strong evidence for nosocomial infection. Epidemiological data showed that these patients were dialyzed during the same shift and in the same area. Phylogenetic analysis of NS5b sequences is useful for determining the HCV genotype and providing evidence of nosocomial transmission.

A cluster of hepatitis C virus infections associated with ozone-enriched transfusion of autologous blood in Rome, Italy

OBJECTIVE

To describe an outbreak of hepatitis C virus (HCV).

DESIGN

Retrospective cohort study.

SETTING

Outpatient department of a hospital in Rome, Italy.

PATIENTS

All 42 patients exposed to ozone therapy by autohemotherapy or intramuscular injection from January to June 2001.

METHODS

Epidemiologic investigation, serologic analysis, and virus genotyping.

RESULTS

Thirty-one (74%) of the patients agreed to participate in the study. Three (9.7%) had symptoms of HCV infection. This incidence rate was higher than the rate of 1.4 per 100,000 per year in the regional population. Six patients were positive for HCV antibodies and HCV RNA for a prevalence rate of 19.4%, which was much higher than the estimate of 0.9% in the population. Virus genotype 1b was found in two case-patients (one symptomatic) and 2c in four case-patients (two symptomatic), one of whom was known to have an HCV infection since 1986 and could have been the source of infection. The infected patients were all being exposed to ozone-enriched transfusions of autologous blood. Although the specific mode of transmission between patients was not detected, transmission probably occurred during one of the three busiest therapeutic sessions in the 6-month period.

CONCLUSIONS

Transmission of HCV infection may occur during medical procedures with limited bleeding. Standard precautions must be applied in any healthcare setting; restricting the number of individuals treated during each therapeutic session could be an effective way of avoiding accidental transmission of infection.

Incidence of HCV infection in French hemodialysis units: a prospective study

A large prospective study was carried out from 1997 to 2000 in 25 French hemodialysis units including 1,323 patients to determine the incidence of hepatitis C virus (HCV) infection. Monthly testing of alanine aminotransferase (ALT) activity, and assessment of HCV RNA and anti-HCV antibodies if the ALT activity was elevated, identified 14 new infections in 7 different units, giving an incidence of 0.4% new HCV infections per year. Molecular analyses and epidemiological data indicated that five patients became infected with HCV outside the unit where they were dialyzed, while the nine remaining patients acquired HCV from infected patients on dialysis during the same shift at the same unit. HCV was cleared in six of the seven (85.7%) patients with acute hepatitis C who were given standard doses of alpha-interferon (alpha-IFN). The persistence of nosocomial transmission of HCV in hemodialysis units emphasizes the need to implement infection control practices. Identifying new infections is crucial because alpha-IFN treatment results in long term clearance of HCV RNA in a large proportion of patients.

Incidence and patterns of hepatitis C virus seroconversion in a cohort of hemodialysis patients

BACKGROUND

The aim of this multicenter hemodialysis (HD) cohort study is to prospectively investigate the incidence of hepatitis C virus (HCV) infection in Greece from 1993 to 1995 and delineate early virological and serological events associated with HCV seroconversion in the HD setting.

METHODS

Sequential serum samples collected weekly from 562 patients were tested biochemically and serologically by means of a second- (EIA-2) and third-generation enzyme immunoassay (EIA-3). All patients with positive antibody to HCV test results (anti-HCV + ) and sequential samples from seroconverting patients were tested for HCV RNA.

RESULTS

Anti-HCV prevalence at study entry was 29% (163 of 562 patients), and viremia was detectable in 110 of 163 anti-HCV + patients (67.5%). HCV incidence was 6.2 cases/100 person-years. Seroconversions could not be attributed to transfusions after study entry (only 1 patient had been administered transfusion), and HD unit was associated with increased hazard for seroconversion ( P = 0.002), even after adjusting for potential differences among their patients. According to Kaplan-Meier estimation, the median interval by which the HCV RNA assay detected HCV infection earlier than anti-HCV testing was 246 and 154 days for EIA-2 and EIA-3, respectively. Detectable HCV RNA and at least 2 consecutive abnormal alanine aminotransferase levels in the preseroconversion period were observed in 29 of 30 (97%) and 14 of 32 patients (44%), respectively. Reductions in HCV RNA levels immediately after seroconversion were transient or did not occur.

CONCLUSION

On the grounds of apparent nosocomial transmission, the wide window period of HCV infection in HD patients emphasizes the need for strict adherence to specific infection-control measures in this setting.

Outbreak of hepatitis C virus infection in an outpatient clinic

BACKGROUND

From January through September 2001, seven patients were admitted to Fukaya Red Cross Hospital with typical clinical manifestations of acute hepatitis. Six were outpatients of the clinic, which is located near the hospital. An extensive survey of clinic outpatients conducted by the local health department revealed six more new acute hepatitis cases during this period.

METHODS

A case control study was carried out to identify potential risk factors for infection. In total, 1946 outpatients with clinic records were scheduled to undergo hepatitis C virus (HCV)-antibody testing. For the HCV-Ab positive patients, HCV-RNA was subtyped and quantified, and sequences of HCV hypervariable region 1 were determined.

RESULTS

Ultimately, 12 patients with acute hepatitis and two asymptomatic subjects were found to be a part of this outbreak. HCV isolates were divided into three major groups using phylogenetic tree analysis. Only a past history of visiting the clinic was significantly associated with acute hepatitis. The timing of the parenteral medical procedure at the clinic and the onset of acute hepatitis strongly suggested association of the two events.

CONCLUSIONS

Our findings suggest that nosocomial HCV infection can occur in an outpatient clinic, even in countries where post-transfusion hepatitis has been almost entirely eliminated.

The Fundamentals of Human Virology

Viruses are molecular pathogens that cause human diseases. A conventional virus is made up of 2 or 3 major components. A nucleic acid genome, which can be Deoxyribonucleic Acid (DNA) or Ribonucleic Acid (RNA), single or double-stranded, contiguous or segmented, contains all the genetic information and encodes all the virus-specific macromolecules of the pathogen. The molecular and pathogenic aspects of their biology are grouped in terms of their genomic organization. Molecular characterization of these pathogens provides an understanding of mechanisms of pathogenesis, rational drug design, molecular signatures that can be used to trace outbreaks of viral disease… An overview of the six families of DNA and 15 families of RNA viruses, based on their molecular properties and life cycles is presented. The utility and issues surrounding the use of molecular forensics and epidemiology to the world of virology are exemplified, for instance, because of rapid sequencing techniques detailed fingerprints of viruses provide important clues about their source. Like other microbial species, the analysis of viral genomic segments can provide important clues as to the relatedness and origins of infections. Given their small size and high rate of evolution, several considerations should be kept in mind when applying comparative molecular forensic analyses to viruses. The tracking of HIV infections exemplifies the successful application of molecular forensics to identify the source of a viral infection. The goal of this chapter is to provide a background in the fundamentals of human virology and provide an overview of the utility and issues surrounding the use of molecular forensics and epidemiology to the world of virology.

Genomic and phylogenetic analysis of hepatitis C virus isolates: a survey of 535 strains circulating in southern France

The present study examines the distribution of Hepatitis C virus (HCV) genotypes in Marseille, France in 2001-2002 and evaluates the efficiency of two in house direct sequence PCR protocols based on 5'NC analysis or NS5B analysis. By 5'NC sequencing, the distribution of 535 HCV strains derived from patients attending gastroenterology and AIDS referral centers, or dialysis units was as follows: 33% were infected by genotype 1a; 26% by 1b; 7% by 2; 22% by 3a; 10.7% by 4. In univariate analysis, HCV distribution was associated with age and source of infection, whereas in multivariate analysis only injecting drug use was an independent determinant for genotype distribution. Among the 535 specimens submitted to 5'NC direct sequencing, 18% could not be classified accurately into subtypes. A subset of 187 samples was amplified efficiently and sequenced by targeting the NS5B region of the viral genome. The two methods yielded concordant results in 70% of cases. Specimens unsubtypeable or misclassified most frequently by 5'NC analysis were type 1b and subtypes 2a/2c and 4a/4c. The data show that 5'NC direct sequence analysis is a sensitive method to identify genotypes in all cases, but that it can lead to subtyping misclassification (in particular, subtype 1b and 1a) or doubtful results (in particular subtypes 2a/2c and 4a/4c). Conversely, NS5B direct sequence assay, based on phylogenetic analysis, allowed better discrimination between subtypes. These two approaches are complementary and should be made available in clinical laboratories to ensure a reliable survey of HCV strains.

Managing occupational risks for hepatitis C transmission in the health care setting

Hepatitis C virus (HCV) infection is a significant contemporary health problem in the United States and elsewhere. Because it is primarily transmitted via blood, hepatitis C infection presents risks for both nosocomial transmission to patients and occupational spread to health care workers. Recent insights into the pathogenesis, immunopathogenesis, natural history, and treatment of infection caused by this unique flavivirus provide a rationale for the use of new strategies for managing occupational hepatitis C infections when they occur. This article reviews this developing information. Recently published data demonstrate success rates in the treatment of "acute hepatitis C syndrome" that approach 100\%, and although these studies are not directly applicable to all occupational infections, they may provide important clues to optimal management strategies. In addition, the article delineates approaches to the prevention of occupational exposures and also addresses the difficult issue of managing HCV-infected health care providers. The article summarizes currently available data about the nosocomial epidemiology of HCV infection and the magnitude of risk and discusses several alternatives for managing exposure and infection. No evidence supports the use of immediate postexposure prophylaxis with immunoglobulin, immunomodulators, or antiviral agents. Based on the very limited data available, the watchful waiting and preemptive therapy strategies described in detail in this article represent reasonable interim approaches to the complex problem of managing occupational HCV infections, at least until more definitive data are obtained.