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

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.

Viral hepatitis in hemodialysis: An update

Hepatitis outbreaks in hemodialysis (HD) patients and staff were reported in the late 1960s, and a number of hepatotropic viruses transmitted by blood and other body fluids have been identified. Hepatitis B virus (HBV) was the first significant hepatotropic virus to be identified in HD centers. HBV infection has been effectively controlled by active vaccination, screening of blood donors, the use of erythropoietin and segregation of HBV carriers. Hepatitis delta virus is a defective virus that can only infect HBV-positive individuals. Hepatitis C virus (HCV) is the most significant cause of non-A, non-B hepatitis and is mainly transmitted by blood transfusion. The introduction in 1990 of routine screening of blood donors for HCV contributed significantly to the control of HCV transmission. An effective HCV vaccine remains an unsolved challenge; however, pegylation of interferon-alfa has made it possible to treat HCV-positive dialysis patients. Unexplained sporadic outbreaks of hepatitis by the mid-1990s prompted the discovery of hepatitis G virus, hepatitis GB virus C and the TT virus. The vigilant observation of guidelines on universal precaution and regular virologic testing are the cornerstones of the effective control of chronic hepatitis in the setting of HD. Major recent advances in the viral diagnosis technology and the development of new oral, direct-acting antiviral agents allow early diagnosis and better therapeutic response. The current update will review the recent developments, controversies and new treatment of viral hepatitis in HD patients.

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.

Surveillance of infection control procedures in dialysis units in Japan: a preliminary study

As there is a high risk of indirect and direct transmission of infectious agents in chronic hemodialysis, infection control procedures should be established in dialysis units. This paper presents the findings of a questionnaire designed to survey the current status of infection control procedures in hemodialysis settings. Two hundred and forty-three hemodialysis units in Japan were surveyed. Nearly 90% of hemodialysis units reported compliance with each procedure recommended by the Center for Disease Control and Prevention in the United States, including use of disposable gloves, handling of non-disposable or non-single-use items, and routine serological testing of blood-borne viruses. However, more than 50% of units reported that they did not comply with recommendations concerning some procedures, such as places for preparing medications and their delivery, clean areas in the units, vaccination for hepatitis B, and additional measures for hepatitis B surface antigen (HBs-Ag) positive patients. Especially, the concept of universal precautions seemed to be misunderstood in units with a high prevalence of anti-hepatitis C antibody-positive (anti-HCV Ab-positive) patients. In conclusion, further intensive education and training will be necessary to establish infection control procedures.

Use of the minimum spanning tree model for molecular epidemiological investigation of a nosocomial outbreak of hepatitis C virus infection

The minimum spanning tree (MST) model was applied to identify the history of transmission of hepatitis C virus (HCV) infection in an outbreak involving five children attending a pediatric oncology-hematology outpatient ward between 1992 and 2000. We collected blood samples from all children attending since 1992, all household contacts, and one health care worker positive for antibody to HCV (anti-HCV). HCV RNA detection was performed with these samples and with smears of routinely collected bone marrow samples. For all isolates, we performed sequence analysis and phylogenetic tree analysis of hypervariable region 1 of the E2 gene. The MST model was applied to clinical-epidemiological and molecular data. No additional cases were detected. All children, but not the health care worker, showed genotype 3a. On six occasions, all but one child had shared the medication room with another patient who later seroconverted. HCV RNA detection in bone marrow smears revealed, in some cases, a delay of several months in anti-HCV responses. Sequence analysis and phylogenetic tree analysis revealed a high identity among the isolates. The MST model applied to molecular data, together with the clinical-epidemiological data, allowed us to identify the source of the outbreak and the most probable patient-to-patient chain of transmission. The management of central venous catheters was suspected to be the probable route of transmission. In conclusion, the MST model, supported by an exhaustive clinical-epidemiological investigation, appears to be a useful tool in tracing the history of transmission in outbreaks of HCV infection.

[Risk factors for hepatitis C virus infection]

INTRODUCTION

Hepatitis C viral infection represents a major health problem in the world. The estimated global incidence is about 3%, whereas the number of chronic hepatitis C virus (HCV) carriers worldwide is estimated to be between 150-300 million people.

MATERIAL AND METHODS

This retrospective analysis included 82 patients whose diagnosis of viral hepatitis C infection was based upon the following criteria: case history, physical examination, laboratory and abdominal ultrasound examination, histological examination of the liver, radiological examination, serological analysis and viral analysis. Descriptive statistics were used to describe general data on patients of the study group, risk factor analysis and follow-up results.

RESULTS

The most prominent risk factor in our study group was intravenous use of drugs in 37 patients (37%), and blood transfusion in 13 patients (13%). Less important risk factors of viral hepatitis C infection included: promiscuity (8%), sexual contact with hepatitis C carriers (5%), surgical intervention (5%), hemodialysis (3%), intranasal use of cocaine (2%).

DISCUSSION

Hepatitis C viral infection has become the illness of young and middle-aged population. This is due to the epidemic profile of this illness, due to intravenous use of drugs as the most prominent risk factor.

CONCLUSION

Due to the number of infected, numerous risk factors and complications of viral hepatitis C, hepatitis C virus has become the most prominent hepatotrophic virus.

A phylogenetic-tree analysis elucidating nosocomial transmission of hepatitis C virus in a haemodialysis unit

Nosocomial transmission of hepatitis C virus (HCV) subtype 1b involving 11 haemodialysis patients occurred in a haemodialysis unit in Japan in March 2000. Sequencing of the HCV-E1 region (411-bp) and phylogenetic-tree analysis showed near identity between HCV isolates derived from these patients and a haemodialysis patient who was known to be HCV-positive. The mode of transmission could not be conclusively established, but retrospective analysis suggested that the sharing of contaminated multidose vials of heparin-saline solutions, which were prepared in the Haemodialysis Center using accidentally contaminated instruments such as needles, may have been responsible for the outbreak. To prevent transmission of HCV in a haemodialysis unit, it may be important to observe strictly standard precautions and to prepare all medications in the Pharmacy. After these measures were taken, no new seroconversions and no new nosocomial transmissions of HCV have been observed in our haemodialysis unit.

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.

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.