Nosocomial transmission of hepatitis C virus in haemodialysis patients

Global epidemiology of hepatitis C virus in dialysis patients: A systematic review and meta-analysis

Dialysis is a replacement therapy for patients with End-Stage Renal Disease (ESRD). Patients on dialysis are at high risk of acquiring hepatitis C virus (HCV), which has become a leading cause of morbidity and mortality in this population. There is a wide range of prevalence of HCV in dialysis populations around the world. It is still unknown how prevalent HCV infection is among worldwide dialysis patients (including those undergoing hemodialysis and peritoneal dialysis). A review was conducted to estimate the global epidemiology of hepatitis C in dialysis patients. We searched PubMed, Excerpta Medica Database (Embase), Global Index Medicus and Web of Science until October 2022. A manual search of references from relevant articles was also conducted. Heterogeneity was evaluated by the χ2 test on Cochrane's Q statistic, and the sources of heterogeneity were investigated using subgroup analysis. In order to assess publication bias, funnel plots and Egger tests were conducted, and pooled HCV prevalence estimates were generated using a DerSimonian and Laird meta-analysis model. The study is registered with PROSPERO under CRD42022237789. We included 634 papers involving 392160 participants. The overall HCV case fatality rate was 38.7% (95% CI = 28.9-49). The global prevalence of HCV infection in dialysis population group were 24.3% [95% CI = 22.6-25.9]. As indicated by UNSD region, country, dialysis type, and HCV diagnostic targeted; Eastern Europe had the highest prevalence of 48.6% [95% CI = 35.2-62], Indonesia had 63.6% [95% CI = 42.9-82], hemodialysis patients had 25.5% [95% CI = 23.8-27.3], and anti-HCV were detected in 24.5% [95% CI = 22.8-26.2]. Dialysis patients, particularly those on hemodialysis, have a high prevalence and case fatality rate of HCV infection. Hemodialysis units need to implement strict infection control measures.

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.

A Large Nosocomial Outbreak of Hepatitis C Virus Infections at a Hemodialysis Center

Objective:

To identify modes of HCV transmission during an outbreak of HCV infection in a hemodialysis unit.

Design:

An epidemiologic study, virologie analysis, assessment of infection control practices and procedures, and technical examination of products and dialysis machines.

Setting:

A private hemodialysis unit treating approximately 70 patients.

Patients:

Detection of HCV RNA by PCR was performed among patients receiving dialysis in 2001. Case-patients were patients who had a first positive result for HCV RNA between January 2001 and January 2002 and either acute hepatitis, a seroconversion for HCV antibodies, or a previous negative result. Three control-patients were randomly selected per case-patient.

Results:

Of the 61 patients treated in the unit in 2001 and not infected with HCV, 22 (36.1%) became case-patients with onset from May 2001 to January 2002 for an incidence density rate of 70 per 100 patient-years. Phylogenic analysis identified four distinct HCV groups and an index case-patient for each with a similar virus among patients already known to be infected. No multidose medication vials or material was shared between patients. Connection to a dialysis machine by a nurse who had connected an HCV-infected patient “just before” or “one patient before” increased the risk of HCV infection, whereas using the same dialysis machine after a patient infected with HCV did not. Understating, lack of training, and breaches in infection control were documented. Direct observation of practices revealed frequent flooding of blood into the double filter on the arterial pressure tubing set.

Conclusions:

During this outbreak, HCV transmission was mainly patient to patient via healthcare workers' hands. However, transmission via dialysis machines because of possible contamination of internal components could not be excluded.

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.

The role the type of vascular access plays in the transmission of hepatitis C virus in a high prevalence hemodialysis unit

BACKGROUND

The necessity of having a vascular access site as well as extracorporeal blood circulation, may add to the risk for patients being dialyzed in units with high HCV prevalence of acquiring hepatitis C virus (HCV) infection. This study endeavors to determine the role the type of vascular access plays in the transmission of HCV infection in the hemodialysis (HD) unit of a Middle Eastern country.

METHODS

The records of 198 patients with end-stage renal disease (ESRD) enrolled on maintenance HD from November 1995 to November 2000 at this tertiary care center, were retrospectively reviewed to match the HCV prevalence and seroconversion rates among patients groups being dialyzed through various types of vascular accesses. Factors such as, number of units of blood transfused and dialytic age (time-span since the initiation of the HD treatment), implicated in transmission of HCV infection in HD units, were also recorded, and compared among these cohorts.

RESULTS

The overall, high HCV seroprevalence of 43.4% (86/198) and annual seroconversion rate of 8.6% per year were recorded. Patients with arteriovenous fistula (AVF) documented peak anti-HCV prevalence [61.7% (63/102)] and annual seroconversion rates (12.3%) as compared to lowest prevalence of 12.9% (4/34) and seroconversion rate of 2.5%, observed among patients with permanent Catheters (PC). Patients dialyzed through polytetrafluoroethylene (PTFE) grafts recorded the next highest HCV prevalence of 47.8% (11/23) with seroconversion rate of 9.5% but temporary catheter (TC) group had HCV prevalence of 19% (8/42) and seroconversion rate of 3.8% [Odd Ratio (OR)-1.58, 95% Confidence Interval (CI) (0.37-7.12), p-NS].

CONCLUSIONS

Considerably higher annual seroconversion rates in AVF [OR-10.90, 95% CI (3.2-40.0), p<0.0001] and PTFE [OR-5.71, 95% CI (1.31-26.79), p<0.016)] groups, appear to suggest that the patients being dialyzed through AVF and PTFE, carried significantly higher risk of acquisition of HCV infection compared to those dialyzed through TC and PC (reference group). This could possibly be attributed to likely accessibility of HCV to blood circulation due to possible breakdown of standard infection control precautions during repeated punctures and cannulations of AVF and PTFE to perform a HD, in a unit with high baseline HCV prevalence.

Hepatitis C virus screening and clinical monitoring of biomarkers in patients undergoing hemodialysis

In this study, 395 volunteers were enrolled to investigate the seroprevalence of hepatitis C virus, the immunological and the alanine aminotransferase (ALT) biomarkers amongst hemodialysis patients, living in Manaus, Brazil. An overall seroprevalence of 13.9% was found in the hemodialysis patients. Analysis of seroconversion patterns demonstrated that most patients with HCV seroconverted up to 10 years following the first hemodialysis session. Anti-NS5 antibody was detectable in 60.4% of patients with HCV. A lower percentage of circulating CD3(+) and CD4(+) T-cells was found in patients seronegative for HCV, whereas a higher frequency of CD8(+) T-cells was the hallmark of patients with HCV. An overall low activation state of monocytes and eosinophils were observed in hemodialysis patients. In contrast, a higher frequency of activated neutrophils was observed in patients with HCV, selectively in the NS5+ subgroup. All hemodialysis patients had a higher percentage of activated lymphocytes, with the higher activation state in patients with NS5- reactivity. Higher ALT levels were observed in patients with HCV, especially in the NS5+ subgroup. Interestingly, the ALT levels were correlated negatively with the lymphocyte activation state, selectively in the NS5- subgroup, suggesting a protective role of these activated lymphocytes in patients with HCV. These findings reinforce the importance of the transmission of HCV among hemodialysis patients, suggesting that apart from the HCV screening, the serological and ALT biomarkers may represent important predictors of morbidity and/or mortality among patients undergoing hemodialysis.

Mathematical modeling of hepatitis C virus transmission in hemodialysis

BACKGROUND

A deterministic mathematical model is developed to explain nontransfusion nosocomial transmission of hepatitis C virus (HCV) from patient to patient during hemodialysis sessions.

METHODS

The model requires 4 sequential steps for cross-transmission: (1) The dialysis session contains at least 1 patient infected with HCV; (2) a hemodialysis staff member connects an uninfected patient to dialysis after having connected an infected patient; (3) the hemodialysis staff member does not change gloves between an infected patient and an uninfected patient; and (4) the uninfected patient is contaminated after exposure to the blood of an infected patient.

RESULTS

We tested the model by comparing observed incidences of HCV infection from epidemiologic studies with calculated incidences. Calculated incidences are closed to observed incidences. We assessed the impact of prevalence of HCV infection, no glove change between patients, and nurse:patient ratio on the incidence of HCV infection. We found linear relationships between incidence and prevalence and between incidence and no glove change, and an increasing logarithmic relationship between incidence and nurse:patient ratio.

CONCLUSION

Our model should be able to estimate the likely incidence of infection in hemodialysis centers. Compliance with recommended hand hygiene and glove use practices, especially glove changes between patients, is essential to prevent HCV infection in hemodialysis centers, particularly those with high HCV prevalence. Mathematical modeling can used as a tool for control.

Change in hepatitis C virus genotype in hemodialysis patients after end-of-treatment response to interferon monotherapy--relapse or re-infection?

Hepatitis C virus (HCV) infection remains common among hemodialysis patients and its occurrence is related mainly to nosocomial spread. Although dialysis patients with HCV infection respond well to interferon-based therapy, relapse is frequent. This study aimed at a selected group of hemodialysis patients infected with HCV infection undergoing interferon therapy who achieved end-of-treatment virological response but became HCV-RNA positive again 6 months after end-of-treatment. It was evaluated whether de novo HCV-RNA positivity in these non-sustained responders occurred due to lack of clearance of HCV after the initial response to interferon-alpha (relapse) or due to re-infection with a new strain (re-infection). Genotyping by Inno-LiPA and by phylogenetic tree analysis using partial HCV-NS5B sequences at two evaluation points: pre-treatment (T0) and 6 months after end-of-treatment (T18). Non-sustained responders (n = 15) carried subtypes 1a (8 patients), 1b (4 patients), 3a (2 patients), and 4a (1 patient) before treatment. Identical subtypes were detected in 10 patients at T18. Five patients changed genotypes at T18, suggesting nosocomial re-infection. This study emphasizes the importance of epidemiologic measures to control the re-exposure of hemodialysis patients treated previously for HCV infection.

Hepatitis C among predialysis patients: prevalence and characteristics in a large cohort of patients

BACKGROUND

The factors associated with hepatitis C virus (HCV) infection in predialysis patients need to be better investigated. The aims of this study were to evaluate the prevalence, risk factors, clinical, biochemical and virological characteristics of chronic HCV infection in predialysis patients.

METHODS

Anti-HCV antibodies were determined in a large cohort of predialysis patients. Epidemiological and laboratorial characteristics of HCV infection were evaluated in predialysis patients and this group was matched to a control group consisting of predialysis patients without viral infection (1:3) and compared in terms of risk factors and alanine aminotransferase (ALT) levels. Logistic regression analysis was applied to identify variables independently associated with chronic HCV infection.

RESULTS

A total of 1,041 patients (61% males) with a mean age of 61 +/- 15 years and mean creatinine clearance of 36 +/- 18 ml/min were included. Forty-one (3.9%) patients were anti-HCV positive and, of these, 39 (95%) presented viremia. Predialysis patients with HCV more frequently showed a history of blood transfusion before 1992 (66.7 vs. 10.3%; p < 0.001) and major surgeries (53.8 vs. 17.1%; p < 0.001), a higher proportion of undetermined etiology of kidney disease (43.6 vs. 17.1%; p = 0.001), and higher ALT levels (1.3 vs. 0.4 xULN; p < 0.001). History of blood transfusion before 1992 (p < 0.001; OR: 19), intravenous drug abuse (p = 0.002; OR: 69) and ALT levels (p < 0.001; OR: 50) were the variables that were independently associated with chronic HCV infection. The accuracy of ALT in detecting HCV infection was 92%. The most prevalent HCV genotype was 1b (48.7%) and 56.5% of patients presented high HCV viral load.

CONCLUSION

Chronic HCV infection among predialysis patients is related to increased parenteral exposure. Elevated ALT levels suggest the need for HCV screening as part of the predialysis care since ALT seems to be a good marker of this infection.

[High prevalence and incidence of hepatitis C virus infections among dialysis patients in the East-Centre of Tunisia]

Hemodialysed patients are recognised as a group at increased risk of infection with hepatitis C virus (HCV). The aim of this study was to determine the prevalence and incidence of HCV infection among dialysis patients of the east-centre part of Tunisia. Two hundred and seventy-six patients dialysed until 2001 were recruited within seven hemodialysis units located in the cities of Sousse, Monastir and Mahdia. The serum markers of HCV infection were tested over the period of March 2000-December 2002, by a 3rd generation ELISA test for antibodies and by qualitative RT-PCR technique for viral RNA. The prevalence of anti-HCV antibodies and of HCV RNA was 32.6% (90 patients) and 25.7% (71 patients), respectively. Between 1998 and 2002, 20 new infections were documented in five of the seven dialysis units corresponding to an incidence of 2.34% per year, with an average time of contamination after the beginning of dialysis of 4.6 years. If all the infections are assessed to have occurred during dialysis, the density of incidence of HCV contamination was 4.4% per year of dialysis. A high correlation was noticed between the presence of HCV markers in serum and the duration of dialysis (F = 34.15, P < 0.0001). In the absence of other risk factors (transfusion, drug-addiction), these results plead for the nosocomial transmission of the observed HCV infections. A phylogenetic analysis of the E2 hypervariable region of the viral genome is in progress to confirm this assumption.

[Prevalence and associated factors to hepatitis C in hemodialysis patients in Brazil]

OBJECTIVE

The prevalence of hepatitis C virus (HCV) is higher in patients on hemodialysis than in the general population, probably due to greater exposure to risk situations. The purposes of the study were to determine anti-HCV antibodies prevalence among hemodialysis patients and dialysis clinics and patients factors associated with HCV transmission.

METHODS

A cross-sectional study was conducted in 752 hemodialysis patients in all 12 dialysis clinics of Fortaleza, Brazil, and were screened using third generation ELISA. Sociodemographic, clinical, and epidemiological data of 663 patients were collected through interviews. Nosocomial factors were assessed using a specific questionnaire tool. Statistical analysis was conducted using Student's t test, odds ratio and multivariate analysis.

RESULTS

The prevalence of anti-HCV was 52% (390/746; ranged from 6% to 72%). The anti-HCV positivity was higher in patients who had previous peritoneal dialysis (OR=1.76; 95% CI 1.12-2.76) and blood transfusion (OR=2.75; 95% CI 1.25-6.03). Dialysis age has been associated with anti-HCV positivity (OR=1.47; 95% CI 1.35-1.61). Clinics practices associated with anti-HCV positivity were: previous preparing of heparin (OR=2.92; 95% CI 1.23-6.92), failure in gloves use or change (OR=5.73; 95% CI 1.75-18.72), unsatisfactory dialysis machine disinfection (OR=2.79; 95% CI 1.57-4.96), and patient isolation in dialysis room (OR=0.18; 95% CI 0.05-0.61).

CONCLUSIONS

The results show high anti-HCV prevalence among hemodialysis patients and the association of nosocomial factors with new HCV infection cases.

Impact of dedicated space, dialysis equipment, and nursing staff on the transmission of hepatitis C virus in a hemodialysis unit of the middle east

BACKGROUND

Infection with the hepatitis C virus (HCV) is endemic in hemodialysis (HD) units, especially in Middle Eastern countries. The meticulous isolation policy recommended for patients with the hepatitis B virus (HBV) in an HD unit resulted in a significant drop in HBV incidence globally. This study was developed to prospectively investigate the impact of an identical isolation policy on incidence of nosocomial HCV infection in this HD unit of the Middle East.

METHODS

In phase I of the study, we retrospectively reviewed the records of 189 patients with a mean age of 47.5 +/- 11.4 years (range, 15-85 years) who were receiving maintenance HD from December 7, 1995, to December 6, 2000, for the mean duration of 73 +/- 6.3 months (range, 3-144 months) to record the prevalence of HCV. Factors such as blood transfusions and dialytic age (time span that patient has received dialysis since its initiation) implicated in transmission of HCV in the HD unit also were recorded. Phase II involved stringent isolation of anti-HCV positive patients detected during phase I through provision of dedicated space, dialysis equipment, and nursing staff from December 7, 2000, to December 6, 2001. Liver function and anti-HCV tests were repeated for all the 198 patients every 6 months to identify new HCV seroconversions.

RESULTS

An HCV prevalence rate of 43.9% (83/189) and an annual HCV seroconversion rate of 6.8% were identified in this cohort. No significant association with blood tranfusion was observed. Eighty-three anti-HCV positive (43.9%) patients had a mean dialytic age of 48.5 +/- 14.2 months compared with 25.0 +/- 8.6 months among 106 (56.1%) anti-HCV negative patients (relative risk [RR], 1.89; 95% confidence interval [CI], 1.39-5.86; P <.001). Only 2 new HCV seroconversions (1.01% [2/198]) were identified.

CONCLUSIONS

Evidently, the sharing of facilities in a high-risk HD environment for a prolonged dialytic age facilitates the nosocomial transmission of HCV infection. A significant decline of annual seroconversion rate from 6.8% to 1.01% (odds ratio [OR], 7.535; 95% CI, 1.598-48.89; P <.005) suggests that a comprehensive, strictly enforced isolation policy for HCV-positive patients may play a significant role in limiting HCV transmission in HD units, just as it has in drastically reducing HBV transmission in these settings.

Outbreak of nosocomial hepatitis C virus infection resolved by genetic analysis of HCV RNA

In July 2000, symptomatic acute hepatitis C was diagnosed in five patients who had attended the emergency room of a municipal hospital on the same day, about 6 weeks before. Investigation of the remaining 65 patients visited at the emergency room on that day disclosed that 8 patients had a positive anti-hepatitis C virus (anti-HCV) test and 4 of them had biochemical evidence of acute anicteric hepatitis. HCV RNA was detected in 12 of the 13 anti-HCV-positive patients. Phylogenetic analysis of the nonstructural 5A (NS5A) and E2 regions showed that 10 patients, including all 9 with acute hepatitis, were infected with a closely related HCV strain, while the remaining 2 patients harbored unrelated strains. Flushing of intravenous catheters with heparin retrieved from a multidose heparin solution in saline was carried out for all the patients involved in the hepatitis outbreak but in only 1 of 23 (4%) matched controls recruited among HCV-noninfected patients attending the emergency room on the same day, and this was the only significant difference concerning risk factors for HCV infection between patients and controls. Thus, accidental contamination of a multidose heparin solution with blood from an unrecognized HCV carrier was identified as the source of this nosocomial outbreak of hepatitis C.

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

Hemodialysis patients are at high risk of infection by hepatitis C virus (HCV). The aim of this study was to investigate an HCV outbreak that occurred in an autodialysis unit by using epidemiological and molecular methods. Seroconversion to HCV antibody (anti-HCV) was observed in two patients over an 18-month period; two other patients had previously been recorded as anti-HCV positive. All four patients involved in the outbreak were tested for HCV RNA, and hepatitis C genotype determination was accomplished by a reverse hybridization assay. Furthermore, part of hypervariable region 1 (HVR1) of the hepatitis C genome was amplified and sequenced in samples from all HCV RNA-positive patients. Phylogenetic analysis of the nucleotide sequences obtained was carried out in order to investigate any possible epidemiological linkages among patients. The nucleotide sequences of the HVR1 regions of both newly infected patients were found to be identical to sequences of samples from previously recorded anti-HCV-positive original patients, suggesting that they were infected by the same isolate. Molecular and epidemiological analysis suggested that nosocomial patient-to-patient transmission was the most likely explanation for the virus spread in the autodialysis unit under study.

Evaluation of disinfectant efficacy against hepatitis C virus using a RT-PCR-based method

The methods traditionally used to evaluate the antiviral activity of antiseptics and disinfectants are based on cell cultures. However, such methods are not applicable to non-cultivable viruses such as hepatitis C (HCV). Therefore, in this case, virucidal activity is normally tested using surrogate viruses able to grow in cell culture. This paper describes a RT-PCR method for testing antiseptic/disinfectant activity against HCV, as a model for non-cultivable viruses. A chlorine-based agent used for skin and tissues, and a 2% glutaraldehyde solution used for endoscope disinfection, were the test materials. The results are discussed in the light of the use of these agents. The method is simple, fast and inexpensive, and could be used for tests on other viruses with minor modification.

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 Goiânia 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.

Investigating hepatitis C virus heterogeneity in a high prevalence setting using heteroduplex tracking analysis

Hepatitis C virus (HCV) infection is very common among chronic hemodialysis patients. In the past, blood transfusion appeared to be the primary risk factor; however evidence of nosocomial HCV transmission in the hemodialysis setting has recently been reported. This report describes a molecular investigation of HCV isolates obtained from a population of 670 patients attending six different Seattle-King County based hemodialysis centers in order to identify potential common source infections. 733 serum specimens were collected from hemodialysis patients in 1992 and 1996, and were tested for HCV antibodies and RNA. Overall, 115 of 670 (17%) patients were positive for HCV RNA, and thus were considered actively infected by HCV. HCV genotype was determined in all cases by restriction fragment length polymorphism, and 93 patients were found to be infected by HCV genotype 1. HCV envelope genes were amplified from the 93 patients with genotype 1 infection, and were studied in further detail by heteroduplex tracking analysis (HTA) using genotype 1a and 1b specific probes derived from the envelope 1 (E1) and envelope 2 (E2) genes. Genetic relatedness between pairs of HCV envelope genes was estimated by calculating the degree of gel shift relative to homoduplex controls. Nucleotide sequencing and phylogenetic analysis was used to confirm genetic relatedness detected by HTA. When HTA was performed using the E1 gene probe, 12 apparently related infections were detected; 10 of 12 (83%) of these infections were confirmed as truly related using the gold standard method of nucleotide sequencing plus phylogenetic analysis. Using an E2 gene probe, 24 infections were apparently related, but only six (25%) were confirmed by sequencing. As a control, 41 envelope genes, which were unrelated by HTA, were sequenced; 0 of 41 (0%) were truly related. In summary, HTA provides a rapid and effective molecular technique for screening HCV genetic relatedness in population-based studies, and should prove valuable in future studies of HCV molecular epidemiology.

Prevalence of infected patients and understaffing have a role in hepatitis C virus transmission in dialysis

To assess hepatitis C virus (HCV) incidence rates and identify determinants of infection among hemodialysis patients, a multicenter study was conducted in 58 units in ITALY: An initial seroprevalence survey was conducted among 3,492 patients already on hemodialysis therapy as of January 1997 and among an additional 434 patients who began dialysis up to January 1998. HCV antibodies were assessed by third-generation enzyme immunoassays. Patients testing seronegative at baseline were enrolled into a 1-year incidence study with serological follow-up at 6 and 12 months. For patients who seroconverted, an HCV RNA assay was performed on stored baseline samples to confirm new infection. A nested case-control study was subsequently performed to investigate potential risk factors. For each incident case, three controls negative for both HCV antibodies and HCV RNA were randomly selected. At enrollment, HCV seroprevalence was 30.0%. During follow-up, 23 new HCV cases were documented, with a cumulative incidence of 9.5 cases/1,000 patient-years. By logistic regression analysis, an increased risk for HCV infection emerged for patients attending the dialysis units with a high prevalence of HCV-infected patients at baseline (odds ratio [OR], 4.6) and for those attending units with a low personnel-patient ratio (OR, 5.4). Among extradialysis factors, a history of surgical intervention in the previous 6 months (OR, 16.7) significantly increased HCV risk. These findings suggest that the combination of understaffing and a high level of infected patients in the dialysis setting increases the risk for HCV nosocomial transmission. This is likely related to an increased likelihood for breaks in infection control measures.

Differences in HCV antibody patterns in haemodialysis patients infected with the same virus isolate

Eight cases of de novo hepatitis C virus (HCV) infection in a haemodialysis unit in Rio de Janeiro, Brazil, were retrospectively studied. HCV viraemia was demonstrated by RT nested PCR in seven of the seroconverters. Genotyping showed that six patients were infected with a genotype 1b strain and one with a genotype 1a strain. A phylogenetic analysis of nucleotide sequences of the HCV core region revealed that five of the six 1b isolates form a separate cluster when compared with other 38 HCV 1b core sequences randomly chosen from the GenBank. The revealed sequence similarities indicated the nosocomial spread of a single HCV strain within the unit. To investigate whether the patients infected with the same viral isolate display similar patterns of antibody response to individual proteins, serial serum samples were examined. A line immunoassay for qualitative and semi-quantitative determination of specific antibodies against recombinant and synthetic HCV antigens was employed. Despite infection with the same virus strain, the patients sera demonstrated different patterns of reactivity against individual structural and nonstructural HCV proteins immediately after seroconversion. For each patient, however, antibody responses remained mostly stable throughout the follow-up of 8 to 24 months.

Hepatitis C virus transmission in a pediatric oncology ward: analysis of an outbreak and review of the literature

Hospital-related hepatitis C virus (HCV) infections continue to occur even after the introduction of blood donor screening. We report an outbreak of HCV in nine patients of a pediatric oncology ward in 1996/1997. Sequencing of the hypervariable genomic region 1 (HVR1) of the E2/NS1 region showed near identity between HCV isolates from these patients as evidence for infection with the same virus. Despite a detailed and careful investigation, the source of infection and the mode of virus transmission could not be established. Based on a review of the current literature about nosocomial HCV infection and HCV infection in children, hypotheses for possible means of transmission in this outbreak are discussed.

Seroprevalence of hepatitis C infection among health care personnel in Beirut, Lebanon

BACKGROUND

Health care workers are at risk of contracting hepatitis C virus (HCV) infection more than the general population, and chronic HCV infection may be asymptomatic. Therefore, the purpose of this study was to determine the seroprevalence of HCV among health care workers at St Georges-Orthodox Hospital, the first study done for a major teaching hospital in Lebanon.

METHODS

Health care personnel at St Georges-Orthodox Hospital, Beirut, were offered anonymous testing for anti-HCV antibody. Seroprevalence rates of health care personnel were compared with the rates of blood donors screened during the same year.

RESULTS

Of the 502 persons screened, 13 (2.60%) initially tested either positive or doubtful-positive by the SM-HCV rapid test; 2 (0.4%) were confirmed positive by 2 commercial enzyme-linked immunosorbent assay kits and reverse transcriptase-polymerase chain reaction. This prevalence rate was comparable with the rate obtained for blood donors (n = 600) during the same period.

CONCLUSION

The seroprevalence of HCV infection among health care workers at St Georges-Orthodox Hospital was similar to the rate observed in local blood donors, which suggests that the occupational risk of HCV infection was low.

HCV: epidemiology, modes of transmission and prevention of spread

Approximately 3% of the world's population has been infected with the hepatitis C virus (HCV), which represents about 170 million chronic carriers at risk of developing serious complications. Following the introduction of screening of blood donors for infection the risk of transmitting HCV by blood products is presently at 1/200,000 units distributed. Intravenous (i.v.) drug users are currently the main risk group with a prevalence rate of about 80% and a yearly incidence varying between 4 and 6%. Vertical and sexual transmissions have also been implicated but data are limited and sometimes controversial. The source of infection for the 30% of cases without an identifiable risk factor remains to be clarified. Prevention of spread includes detailed information of persons at risk of being infected, screening of high-risk populations, strengthening of syringe exchanges among i.v. drug users and strict application of disinfection procedures for all invasive medical equipment.

Molecular epidemiology of an outbreak of HCV in a hemodialysis unit: direct sequencing of HCV-HVR1 as an appropriate tool for phylogenetic analysis

Infection with hepatitis C virus (HCV) is still a serious problem in hemodialysis patients, despite screening of blood products for anti-HCV antibodies. The prevalence of HCV in HD patients is between 15% and 30% in Germany. We report the molecular epidemiology of an HCV outbreak in a hemodialysis unit in 1997 is determined. HCV hypervariable region 1 (HVR1) was amplified from serum samples of 19 patients by polymerase chain reaction (PCR) and sequenced directly. In addition, HCV isolates from 3 of these 19 patients were cloned and sequenced. 14 newly infected patients and two patients, who had been infected for several years had very closely related HCV isolates. Unrelated HCV isolates as well as sequences obtained from an HCV outbreak in a plasmapheresis center were found in different, distantly related branches. These findings provide strong evidence for nosocomial transmission of the virus, despite following strict general hygiene precautions. The production of anti-HCV antibody was delayed significantly or seroconversion did not occur at all during the period of observation in 8 out of 14 newly infected HCV RNA positive patients. Close-meshed reverse transcription-polymerase chain reaction (RT-PCR) analyses on apparently non infected patients within hemodialysis units and upon admission of new patients is strongly recommended for the early detection and prevention of outbreaks of HCV.

Nosocomial transmission of hepatitis C virus

Nosocomial transmission of hepatitis C virus (HCV) may occur in a variety of circumstances. This problem is best characterised in haemodialysis units. In this setting, molecular analysis of viral isolates indicates that patient to patient is the most frequent mode of HCV transmission. Spreading of HCV is mainly related to non-strict observance of universal precautionary measures, which are an efficient and, possibly, sufficient means for prevention. Epidemics or single instances of patient-to-patient transmission have only occasionally been reported in hospital settings other than haemodialysis units, and, again, non-observance of universal precautionary measures, or inadequate cleaning or disinfecting of medical instruments was involved. Transmission from an infected surgeon to patients has been reported, but infection from doctors to patients seems to be exceptional. Thus, although prospective studies have not been performed, nosocomial transmission of HCV unrelated to haemodialysis appears to be an infrequent and preventable event.

Hepatitis C virus infection in Western Europe

Hepatitis C virus (HCV) infection is now recognised as the most common infection causing chronic liver disease in Europe. Approximately 3% of the world population has been infected with HCV, which represents about 170 million chronic carriers at risk of developing serious complications with more than 5 million in Europe alone. In the general population, the prevalence varies geographically from about 0.5% in northern countries to 2% in Mediterranean countries. Among newly detected HCV cases, 40-60% have normal ALT levels, 80% are viraemic, while about 70% of newly detected HCV carriers present histologic liver disease. More than 75% of the cases remain to be identified. The residual risk for transmitting HCV by blood products is at present 1/200 000 units distributed. Intravenous drug users are currently the main risk group. The prevalence rate is about 80% and the yearly incidence varies between 4 and 6%. In haemodialysis patients, the prevalence ranges from 10% to 30% and the incidence from 3% to 7%. The source of infection for the 30% of cases without identifiable risk factor remains to be clarified and appropriate well-controlled case-control studies on large samples are necessary. Further training and information campaigns remain desirable to improve knowledge and awareness among health care professionals.

Hepatitis C virus and blood transfusion: past and present risks

The risk of HCV transmission by blood and blood products has been greatly reduced since the early 1980's. Selection of non-remunerated donors, donor selection to prevent HIV transmission, initial surrogate testing in some regions, and introduction of anti-HCV testing have all contributed to this. ALT surrogate testing has become obsolete since the introduction of anti-HCV testing. The residual risk of HCV transmission due to donations in the anti-HCV window period at present is about 1 in 100 000 transfusions of cellular products, and transmission of HCV by plasma products treated with modern inactivation methods such as solvent-detergent treatment, has not been reported. Hemovigilance programmes, which are presently being installed, will provide more data on the safety of blood transfusion. Introduction of HCV nucleic amplification technology (NAT) as a quality control of manufacturing pools for plasma products or as a form of blood donor screening by minipools is anticipated in many European countries for the coming year. Given industrial developments, NAT testing of individual blood donations may become available within the next 2 years. HCV NAT testing will further annihilate the residual risk, and the cost-effectiveness will become relatively low in comparison with other public health measures.

Molecular evidence for nosocomial transmission of hepatitis C virus in a French hemodialysis unit

A systematic virological follow-up of hemodialysis patients identified 11 cases of de novo hepatitis C virus (HCV) infection in the same unit that were not due to blood transfusion. There were three groups of infection, each occurring within a period of 3 months: four infections with genotype 1b, two infections with genotype 1b, and five infections, four with genotype 1a and one with genotype 5a. The possibility of patient-to-patient transmission was addressed by sequencing the first hypervariable region of the HCV genome in sera taken shortly after infection. Phylogenetic analysis indicated clustering of most of the cases of de novo infections. Sequence homologies identified potential contaminators among already infected patients. All patients who were infected with closely related HCV isolates were found to have been treated in the same area and during the same shift or on the previous one. These infections could have been due to occasional breaches of the usual hygiene measures. Strict adhesion to hygiene standards and routines, continuously supervised, remains the key rule in the management of dialysis patients. Nevertheless, the isolation of patients with HCV could reduce the risk of infection because occasional lapses of preventive hygiene measures or unpredictable accidents can always take place in a hemodialysis unit. This policy needs to be evaluated by large-scale prospective studies.

Detection of HGV in serum and peripheral blood mononuclear cells of maintenance haemodialysis patients

The aim of the present study was to investigate the prevalence of hepatitis G virus (HGV) and also hepatitis C virus (HCV) infections in maintenance haemodialysis patients, and to identify extrahepatic sites as HGV reservoirs. HGV RNA was detected in the serum of 6/61 (10%) patients and in the peripheral blood mononuclear cells of 2/61 (3%) patients (one of whom was serum negative). These findings suggest that lymphoid cells constitute an extrahepatic HGV reservoir. HCV RNA was detected in 7/61 (11%) patients. Five of these patients (71%) were identified as carrying HCV genotype 1b. Co-infection with HCV and HGV was detected only in one patient. Haemodialysis patients are at risk for HGV infection, by nosocomial routes or via transfusions. HGV itself does not seem to be an important cause of hepatitis since all six HGV RNA positive patients not co-infected by HCV or HBV showed normal ALT values.

Hepatitis C in a hemodialysis unit: molecular evidence for nosocomial transmission

This study reports four cases of transmission of the rare hepatitis C virus genotype 4 which occurred in a hemodialysis unit and originated from a single source of infection. Phylogenetic analyses performed with the NS5b domain showed that all four patients with secondary infections were infected with virus strains very similar to that of the index patient. Cross infections probably resulted from breaches in safety precautions and lack of dialysis machine sterilization.

Confirmation of nosocomial transmission of hepatitis C virus by phylogenetic analysis of the NS5-B region

Four hepatitis C virus transmission chains at three dialysis units were disclosed by limited sequencing; three of these were disclosed by analysis of the NS5-B region of the genome. Dialysis on the same shift as that during which infected patients were dialyzed was the common factor for seven patients in two chains. Two nurses exposed to needle sticks and their sources of infection constituted two other chains. The strains of three chains belonged to subtype 1a and formed clusters with an intrachain variability of 0 to 6 nucleotides compared to 8 to 37 nucleotides for unrelated strains within this subtype. The clusters were supported by bootstrap values ranging from 89 to 100%.

Genetic and serological evidence for multiple instances of unrecognized transmission of hepatitis C virus in hemodialysis units

We investigated the unrecognized patient-to-patient transmission of hepatitis C virus (HCV) in hemodialysis units by performing phylogenetic and serological analyses of hypervariable region 1 (HVR1) of HCV. Of the 62 patients in one center, 11 were positive for HCV RNA. A total of 24 HVR1 sequences, including the minor population of sequences of HCV isolates, from each patient were closely related and classified into five clusters by phylogenetic analysis. Of the 11 patients, 5 were infected with multiple clusters of HCV. Two patients were infected with HCV during an 18-month interval between examinations, and these HVR1 sequences fell into one of the five clusters. In another hemodialysis center, 5 of the 20 patients were HCV RNA positive, and two HVR1 sequences were found to be closely related and phylogenetically derived from the same cluster. The antibody responses of these patients to the HVR1 peptides representative of the genetic clusters revealed exactly the same clustering as that shown by phylogenetic analysis. These findings suggest that phylogenetic and serological analyses of HVR1 sensitively detect unrecognized and multiple transmission of HCV occurring within the same room in hemodialysis centers. Fingerprinting analyses using hypervariable regions of infectious agents are useful in identifying the precise route of transmission of infection.