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

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.

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.

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.

Risk factors for hepatitis B and C in multi-transfused patients in Uruguay

BACKGROUND

In spite of the progress made in the prevention of transfusion-transmitted infections over the last years, these still occur. It was considered that infection by hepatitis B (HBV) and C (HCV) viruses could be a major problem in Uruguay, especially among high-risk individuals, such as multi-transfused patients.

OBJECTIVES

To assess the prevalence of HBV and HCV infection among multi-transfused Uruguayan patients and the impact of serological screening; to evaluate the role of number of transfusions and other potential risk factors for the acquisition of HBV and HCV infection.

STUDY DESIGN

Cross-sectional study of HCV antibodies, HBV surface antigen (HBsAg) and HBV core antibodies (HBcAc) in 409 multi-transfused patients.

RESULTS

Of 409 patients studied, 147 (35.9%) received blood products due to acute bleeding, 118 (28.9%) were hemato-oncological, 75 (18.3%) hemophiliacs, 64 (15.6%) were on hemodialysis and 5 (1.2%) suffered sickle cell anemia. Prevalence of HCV antibody was 12.7%. Of the HCV positive patients, 45 were hemophiliacs, for a prevalence rate of 60.0%. The prevalence rates for hemodialysis and acute bleeding patients were 6.3% and 2.0%, respectively. Prevalence of HBsAg was 1.0%; 16.6% of subjects were positive for HBcAc. The prevalence rates of HBcAc were 48.0%, 15.0% and 3.1% among hemophiliacs, acute bleeding and hemodialysis patients, respectively. There was a direct relationship between the number of products transfused and prevalence of both hepatitis C antibodies and HBcAc. Higher prevalence of HCV and HBcAc was observed among the group of patients who received transfusions before the systematic screening of blood donors.

CONCLUSIONS

Exposure to blood transfusions was the main risk factor for HCV and HBV infection. The systematic serological screening of blood donors was highly effective in reducing transfusion transmitted infections.

Hepatitis C virus infection among dialysis patients in Tunisia: incidence and molecular evidence for nosocomial transmission

In order to study the incidence of hepatitis C virus (HCV) infection in Tunisian haemodialysis patients and detect its nosocomial transmission, 395 patients were enrolled in a prospective study (November 2001-2003). HCV serological and virological status was determined initially using, respectively a third generation ELISA and an RT-PCR qualitative assay. The genotype of the HCV isolates was determined by sequencing NS5B region. The issue of nosocomial transmission was addressed by sequencing the HVR-1 region of the E2 gene. About 20% of the patients had anti-HCV antibodies and HCV-RNA was detected in 73% of the anti-HCV positive patients. Two cases of de novo HCV infection were identified in two dialysis centers, during virological follow-up of patients susceptible to HCV infection. The incidence of de novo HCV infection was 0.5%. Determining the genotypes in the first center disclosed that all HCV-positive patients were infected with genotype 1b; sequencing of the HVR-1 region of the E2 gene provided strong evidence that the isolate from the newly infected patient and another infected dialysis patient were closely related, confirming nosocomial contamination. The investigation of the second center is pending. Besides, one patient with negative HCV serology had detectable HCV-RNA at the beginning of the study. This case had HCV genotype 1b, two other infected dialysis patients in the same unit had HCV genotypes 4k and 3a; thus precluding nosocomial transmission. Thanks to molecular and phylogenetic methods, one case of nosocomial HCV transmission in haemodialysis was confirmed. Epidemiological investigation suggested nosocomial transmission via the medical and/or nursing staff.

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.

Brote de 18 casos de hepatitis C en una unidad de hemodiálisis

OBJECTIVES

On September 30, 2001 we had notice of a probable outbreak of hepatitis C virus (HCV) infection in a hemodialysis unit in Ciudad Real (Spain). We conducted an investigation of the outbreak to determine its cause and implement control measures.

METHODS

We performed a descriptive study and another analytic study (retrospective cohort study). In the descriptive study, the incidence of HCV infection in the unit between 01/01/98 and 09/30/01 was studied. In the cohort study, 86 subjects were included, of which 18 were infected with HCV during the outbreak. Virologic study was performed, including serology of anti-HCV antibodies, specific IgG avidity study, polymerase chain reaction and phylogenetic analysis of the viral subtypes found.

RESULTS

In the study period, there were 86 patients under treatment in the hemodialysis unit, of which 27 (31.4%) were HCV-positive before 03/01/01. The epidemic curve suggested a common source with secondary cases. Since 1998 only one seroconversion had been documented (in 1999). Statistically significant differences were found only for the variable of dialysis shift. None of the patients who underwent dialysis on the Tuesday-Saturday-Thursday shift exclusively was infected. All cases were genosubtype 4d, which is uncommon in Spain (accounting for 3%), suggesting a common initial source for all cases. Most of the previous cases of HCV in the hemodialysis unit were 1b; three were 4c/4d and one was 1a. The IgG avidity study suggested that not all the cases were infected at the same time, supporting the hypothesis of a common source with secondary spread.

CONCLUSIONS

The outbreak of HCV was confirmed, with 18 cases among dialyzed patients in the central unit. The outbreak was caused by the same viral strain, probably due to a common source with secondary person-to-person transmission among the patients.

Detection of hepatitis C virus antibody and RNA in hemostatic gauze used for dentistry

We investigated whether the presence of hepatitis C virus (HCV) infection can be detected in hemostatic gauze used during oral treatments. We were able to detect both antibody to HCV and HCV RNA in samples from patients serologically proven to have HCV and also in gauze used for these patients that was left at room temperature even for as long as 24 hours. Thus, this method is useful for the screening of HCV infection in situations in which blood sampling is not feasible.

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.

Prevalence and risk factors of hepatitis C virus infection in haemodialysis patients: a multicentre study in 2796 patients

BACKGROUND

Hepatitis C virus (HCV) infection is a significant problem in the management of haemodialysis patients. A high prevalence of HCV infection in haemodialysis patients has been reported. Risk factors such as the number of blood transfusions or duration on haemodialysis have been identified.

AIM

To determine the prevalence of HCV by antibody testing and HCV-RNA determination by polymerase chain reaction (PCR) in haemodialysis patients. Furthermore, liver function tests were performed and epidemiological data were obtained to determine risk factors for HCV in this cohort of patients.

RESULTS

A total of 2796 patients from 43 dialysis centres were enrolled. The overall prevalence of HCV (HCV antibody and/or HCV-RNA positivity) was 7.0% (195 patients). Antibody positivity occurred in 171 patients (6.1%). Viraemia was detectable in 111 patients (4.0%). Twenty four of 111 HCV RNA positive patients (21.6%) were negative for HCV antibodies. Thus 0.8% of the entire study population was HCV positive but could not be diagnosed by routine HCV antibody testing. Major risk factors identified by a standard questionnaire in 1717 of 2796 patients were the number of blood transfusions individuals had received and duration of dialysis, the latter including patients who received no blood transfusions. Sequencing of the 5'untranslated region of the genome showed a dominant genotype 1 (77.6%) within the cohort. Further reverse transcription-PCR of the NS5b and core region were performed to document phylogenetic analysis. Comparing nucleic acid sequences detected by PCR, no homogeneity was found and thus nosocomial transmission was excluded.

CONCLUSIONS

HCV is common in German haemodialysis patients but screening for HCV antibodies alone does not exclude infection with HCV.

Phylogenetic investigation for the risk of hepatitis C virus transmission to surgical and dental patients

Blood loss during treatment carries a potential risk for the transmission of blood-borne pathogens in hospital patients. To determine whether nosocomial transmission of hepatitis C virus (HCV) occurs in surgical wards and dental hospitals, we tested anti-HCV antibodies and HCV RNA in sera from these patients and analysed the hypervariable region 1 (HVR1) sequence of HCV phylogenetically in the HCV RNA-positive patients. Five of 83 patients from a surgical ward were positive for HCV RNA, and six patients from one dental hospital and nine patients from a second were found to be positive for HCV RNA during the examination period. The HVR1 sequences were amplified from these patients' serum, and after subcloning, multiple clones of the HVR1 sequence from each patient were determined. The phylogenetic analysis of these sequences showed that HVR1 species from each patient could be classified into one to three genetic clusters of HVR1 quasi-species and that these clusters were independent of each other among patients. Thus, there was no evidence of HCV transmission in our study, and unrecognized transmission of HCV may be a rare event in surgical and dental patients at university hospitals.

Hepatitis C virus in blood and dialysate in hemodialysis

The prevalence of hepatitis C virus (HCV) positivity among hemodialysis patients remains high compared with that of the healthy population, and thus the issue of safety and environmental protection must be addressed. The purpose of this study is to evaluate the dynamics of prehemodialysis and posthemodialysis blood HCV levels and HCV escape to spent dialysate. Because heparin has an inhibitory effect on the reverse-transcription polymerase chain reaction (RT-PCR) assay, a serine protease inhibitor (nafamostat mesilate) was used as the anticoagulant for hemodialysis. High-flux polysulfone membrane dialyzers were used; dialyzer reuse was not performed. Multicyclic RT-PCR was performed for the quantitative detection of HCV. To elucidate HCV escape to spent dialysate, a portion of total spent dialysate was continuously extracted in a sterile fashion using a minutely adjusted syringe pump. No HCV extravasation to spent dialysate was found, although HCV copy numbers were reduced to a statistically significant level in postdialysis blood compared with predialysis levels (P: < 0.05; n = 20). The need to establish standards for risk management in dialysis centers is evident. The data obtained in this study strongly suggest that to minimize the risk for HCV transmission, lower transmembrane pressure (TMP) should be used in the hemodialysis of HCV-positive patients, with fresh polysulfone dialyzers and dialysis settings of 180 to 250 mL/min for blood flow, 500 mL/min for dialysate flow, and less than 18.72 mm Hg for TMP.

Phylogenetic evidence, by multiple clone analysis of hypervariable region 1, for the transmission of hepatitis C virus to chronic haemodialysis patients

We analysed hepatitis C virus (HCV) sequences to determine whether nosocomial transmission of HCV occurred in a haemodialysis unit. Twenty patients positive for serum HCV RNA were investigated. All were undergoing haemodialysis therapy in the same room. The hypervariable region 1 (HVR1) sequence of HCV was amplified and multiple clones sequenced. Phylogenetic analysis of these sequences revealed five genetic clusters consisting of HCV isolates from 11 of the 20 patients. In addition to two genetic clusters of HCV isolates from the four currently seroconverting patients and another patient who had been persistently infected, we identified three other phylogenetic relationships in HCV isolates from six patients. The patients grouped into the same cluster received haemodialysis individually on the same shift and/or side-by-side. Phylogenetic analysis of HCV HVR1 sequences corroborated the patient-to-patient HCV transmission suggested by an epidemiological study and that unrecognized transmission of HCV occurs in the dialysis room. Our multiple clone analysis of HCV isolates provides detailed information on nosocomial transmission of HCV. Transmission occurs more frequently when treatment is performed at the same time than in consoles located close to each other.

Molecular analysis of HCV type 1 to 5 envelope gene: application to investigations of posttransfusion transmission of HCV

BACKGROUND

Until 1990, HCV infection was common in transfused patients, resulting in more than 200,000 cases of posttransfusion hepatitis C in France alone. A molecular method that permits the investigation of posttransfusion hepatitis C infections is presented.

STUDY DESIGN AND METHODS

Viral sequences in the envelope region of HCV were obtained for 12 pairs of blood recipients and their respective blood donors. The HCV strains studied belonged to types 1 (subtypes 1a and 1b), 2, 3, 4, and 5. Genetic distances and mutation rates were determined, and sequences were submitted to phylogenetic analysis along with sequences retrieved from nucleotide databases.

RESULTS

Pairwise distances in the donor-recipient pairs were found to be less than 0.05 mutation per site, which corresponds to a mutation rate ranging from 0.6 x 10(-3) to 2.1 x 10(-3) per site per year. Sequences obtained from the 12 donor-recipient pairs clustered in 12 monophyletic nests.

CONCLUSION

The genetic analysis of the envelope region of HCV can be used for the forensic evaluation of virus transmission. It permits the refutation of a link between blood transfusion and HCV transmission, rather than proof of the existence of such a link.

Occasional infection of hepatitis C virus occurring in haemodialysis units identified by serial monitoring of the virus infection

To examine whether hepatitis C virus (HCV) infection still occurs in haemodialysis units even after a decrease in the number of blood transfusions and in those contaminated with HCV, we tested anti-HCV antibodies and HCV RNA in 142 patients from Japanese haemodialysis units, and examined the serial prevalence of anti-HCV antibodies in 86 patients from 1992 to 1997. A high prevalence of HCV infection was observed: 34 (23.9%) and 38 (26.8%) of the 142 patients were positive for serum anti-HCV antibodies and HCV RNA, respectively. These positive rates were related to the duration of haemodialysis. We found that five patients treated in the same unit seroconverted from 1993 to 1995. Four of the five patients had been treated at the same shift and were affected at the same time. Phylogenetic analysis of the hypervariable region 1 (HVR1) sequence of HCV from serum of these patients showed that three of the four patients' sequences were phylogenetically clustered and that two of the three were closely related. Thus, an occasional transmission of HCV occurred in the haemodialysis unit. The universal precautions by staff such as carefully changing gloves may be important in inhibiting spread of HCV because no instances of infection have been seen since the instigation of educational measures for unit staff.

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.