Hepatitis C virus seroconversion and genotype prevalence in patients and staff on chronic hemodialysis

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.

Distribution of HCV genotypes in patients with end-stage renal disease according to type of dialysis treatment

The objective of this study was to investigate the effects of types of dialysis treatments on hepatitis C virus infection and the epidemiologic properties of hepatitis C virus (HCV) infection at three Baskent University hospitals, in Ankara, Adana, and Izmir, Turkey, in 655, 326, and 118 patients with end-stage renal disease, respectively. One hundred thirty patients with HCV viremia among 271 patients with end-stage renal disease seropositive for HCV were included in this cross-sectional study. HCV RNA-positive patients were classified according to the renal replacement therapies (hemodialysis or continuous ambulatory peritoneal dialysis), and viral load, transaminase levels, and distribution of genotypes were compared between these subgroups. In the continuous ambulatory peritoneal dialysis group, 26 of 165 patients (16%) were serum anti-HCV positive, and 11 of 26 patients (42%) were serum HCV RNA positive. Twenty-six percent of the patients undergoing hemodialysis were anti-HCV positive, and 49% were HCV RNA positive. The prevalence of genotype 1b was 68% and 73% for patients in the continuous ambulatory peritoneal dialysis and hemodialysis groups, respectively. No significant differences were found between the genotype 1b and the non-1b groups or between different dialysis types with regard to age and sex and serum aspartate transaminase, alanine aminotransferase, and HCV RNA levels. We conclude that HCV seropositivity may differ between different types of dialysis treatments, although viral load and genotypes may be similar in persons with end-stage renal disease and those without.

Unexpected distribution of hepatitis C virus genotypes in patients on hemodialysis and kidney transplant recipients

The distribution of hepatitis C virus (HCV) genotypes in patients on hemodialysis and in kidney transplant recipients was compared with that observed in a control group composed of HCV-infected individuals from the general population. A total of 340 patients were included in the study: 46 with end-stage renal disease on regular hemodialysis treatment, 22 kidney transplant recipients and 272 controls matched for sex and age at a 4:1 ratio (controls to patient). HCV genotype was determined by sequencing of the 5' untranslated region of the HCV genome. No difference was observed in the distribution of HCV genotypes in hemodialysis patients and renal transplant patients (P = 0.47). However, when each of these groups was compared with the control group, a significant difference was detected in the genotype distribution (P < 0.001). In hemodialysis and renal transplant patients the most prevalent subtype was 1a, followed by 1b, 3, and other less prevalent genotypes (2, 4, and 5), whereas in the control group the most prevalent subtype was 1b, followed by 3, 1a, and others. That observation may reflect differences in the epidemiology of HCV infection, viral characteristics and host factors in renal patients in comparison to the control group.

Viraemia, cryoglobulins and autoantibodies in haemodialysis patients infected with hepatitis C virus

OBJECTIVES

The clinical features of hepatitis C virus (HCV) infection depend on the immune and autoimmune reactions induced by the virus. Chronic renal failure might alter the pattern of these reactions. The aim of this study was to determine the prevalence of cryoglobulinaemia, the frequency of autoantibodies and HCV viral load in HCV infected Greek patients on chronic haemodialysis.

METHODS

Seventy-three HCV Ab(+) patients on maintenance haemodialysis and 87 otherwise normal patients with chronic HCV infection were evaluated for the presence of cryoglobulins, autoantibodies and viral markers.

RESULTS

Cryoglobulins were detected in 22/73 (30.1%) haemodialysis patients and in 23/87 (26.4%) patients with normal renal function (NS). The mean cryocrit value was significantly lower in the haemodialysis group ( = 0.002). Haemodialysis patients had significantly higher levels of C4 component of complement and lower incidence of rheumatoid factor than those of patients with normal renal function. Serum HCV RNA levels were found significantly lower in the haemodialysis group (median, 2.20 Meq/ml; range, 119.9 Meq/ml) than in the group with normal renal function (median, 4.50 Meq/ml; range, 114.9 Meq/ml; = 0.046). The distribution of genotypes was not different between the two groups.

CONCLUSIONS

There are subtle differences in autoimmune features of HCV infection if the patients are also haemodialysed for renal failure. HCV viral load is lower in haemodialysis patients, with no difference in the HCV genotype prevalence. The clinical significance of these findings is unknown.

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.

Automated RIBA HCV strip immunoblot assay: a novel tool for the diagnosis of hepatitis C virus infection in hemodialysis patients

Hemodialysis (HD) patients remain a high-risk group for hepatitis C virus (HCV) infection. Serological assays (enzyme-linked immunosorbent assays, ELISAs) are the only tests currently approved by the Food and Drug Administration in the United States for the diagnosis of HCV. The RIBA HCV Strip Immunoblot Assay (SIA) is an established method for supplemental testing of repeat reactive hepatitis C ELISA patients on HD. However, the current manual procedure is labor intensive, requiring subjective band scoring and result interpretation. Recently, the automated CHIRON RIBA HCV Processor System has been designed to perform RIBA supplemental testing. The CHIRON RIBA HCV Processor System consists of a bench-top instrument that provides objective evaluation of the RIBA immunoblot strips, by measuring the light differentially reflected from the developed bands and white background, creating a density of reflectance. The CHIRON RIBA HCV Processor System assesses the intensity of each of the reactive bands in relation to the intensity of the internal control bands on each RIBA HCV strip. Comparison between processor and manual protocols was performed using a large (n = 200) cohort of ELISA 3.0 HCV negative and positive patients on maintenance HD. The test characteristics of RIBA HCV 3.0 SIA were identical with manual and automated runs. The relative intensity values of antigenic bands by the CHIRON RIBA HCV 3.0 Processor System between anti-HCV positive and negative patients were significantly different; only 15 of 784 (1.9%) antigenic bands had borderline reactivities. The correlation of test results between manual and automated runs was very high (kappa value 0.989). Among positive results by RIBA HCV 3.0 SIA, there was a strong concordance between manual and automated runs with regard to the pattern of reactivity (kappa value 0.943). The discordant results between manual and automated protocols were attributable to increased variability of antigen scores close to the cutoff value for both tests. In conclusion, the CHIRON RIBA HCV 3.0 Processor System is capable of performing RIBA HCV 3.0 SIA in the HD population accurately with minimal operator involvement. The test characteristics of RIBA HCV 3.0 SIA were identical by manual and automated runs. There was a strong correlation between the results of the manual and automated runs; the few discordant results between the two procedures were mostly due to increased variability of antigen scores close to the cutoff value for both tests. The Centers for Disease Control and Prevention in the USA have recently included chronic HD patients among those persons for whom routine HCV testing is recommended; HCV-infected patients on HD often have a high rate of indeterminate results by manual RIBA technology which is operator dependent for band scoring and result interpretation. The CHIRON RIBA HCV 3.0 Processor System may be very useful for supplemental anti-HCV testing of ELISA repeat reactive specimens in clinical practice within dialysis units.