Prevalence of antibodies against hepatitis C virus in a dialysis unit

[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.

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.

Intrafamilial transmission of hepatitis C virus: a systematic review

To examine the risk of hepatitis C virus (HCV) transmission between patients infected with HCV and their household members (siblings, offspring and parents), as well as their stable heterosexual partners, a systematic search of the MEDLINE database was undertaken for all relevant articles published up to June 1997. English language publications or those supplemented with an English abstract that reported studies concerning hepatitis C, and household, intrafamilial, sexual and intraspousal transmission of HCV, were reviewed. Data from uncontrolled and controlled studies were collected and analysed separately. Studies reporting the exclusive use of first-generation anti-HCV antibodies without supplemental tests were excluded. Pre- or postnatal mother-to-child transmission of HCV and homosexual and heterosexual transmission of HCV among non-permanent couples were not included. Unweighted data from individual studies were pooled for each category of family member. Data were also analysed separately for Japanese and non-Japanese studies because there is evidence that intrafamilial transmission may differ, based on endemicity of the viral infection. Comparisons were drawn only from controlled studies that reported the prevalence of HCV in family members of both HCV-positive and HCV-negative controls. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated for each family category. In uncontrolled studies, the pooled prevalence of anti-HCV among 4250 stable sexual contacts of patients with HCV-related chronic liver disease (CLD) was 13.48%, while the pooled prevalence of anti-HCV among 580 stable sexual contacts of patients who contracted HCV as a result of multiple transfusions was 2.41%. In controlled studies, the pooled prevalence of anti-HCV among 175 siblings and household contacts of patients with CLD was 4.0% compared with 0% among 109 contacts of anti-HCV-negative controls (OR 9.75, 95% CI 0.91 ad infinitum). The pooled prevalence of anti-HCV among offspring of Japanese HCV-infected CLD patients was 17% compared with 10.4% among offspring of HCV-negative Japanese controls (OR 1.77, 95% CI 1.21-2. 58, P=0.002). The pooled prevalence of anti-HCV among spouses of non-Japanese HCV-infected CLD patients was 15.2% compared with 0.9% in the spouses of non-Japanese HCV-negative controls (OR 20.57, 95% CI 6.05-84.08, P=0.0001). The prevalence of anti-HCV among non-Japanese offspring and Japanese spouses of HCV-infected patients was not increased compared with controls. HCV genotype homology and mutant analysis studies in pairs of HCV-infected patients and their HCV-infected contacts showed that concordant genotype homology was found in 66% of non-sexual contacts and in 74% of sexual contacts. Sequence homology of greater than 92% was found in 19 out of 35 pairs. Hence, evidence exists that familial, non-sexual and sexual transmission of HCV does occur. In Japanese patients, transmission probably occurs in younger family members while, in non-Japanese patients, transmission probably occurs at an older age, after contact with an HCV-infected spouse.

Hepatitis C infection in transplantation

This review emphasizes the role of HCV in the transplant setting. Prolonged HCV infection results in end-stage liver disease and as such represents a common indication for liver transplantation. Recurrence of infection is almost universal after transplantation in those with viremia before transplantation. Acquired disease is uncommon but nevertheless important, particularly in organ populations in whom screening for infection is not routine. The natural history of post-transplantation disease suggests that the effect on graft or patient survival is minor, at least during short-term follow-up. Long-term follow-up is needed, as well as more detailed study of the factors contributing to severity of post-transplantation disease. Kidney transplant recipients are commonly infected with HCV prior to transplantation. HCV infection after transplantation is associated with an increased risk of liver disease and infectious complications, but its effect on survival is still controversial. Similarly, observations in recipients of other solid organ transplants, such as heart and lung, and bone marrow patients suggest that HCV infection usually is not a major cause of mortality in the first 5 to 10 years of follow-up. Many issues still need to be addressed. The most important is the identification of factors that contribute to disease progression. Finally, effective therapies to eradicate infection and prevent disease progression are awaited.

Hepatitis in patients with end-stage renal disease

Hepatitis B and hepatitis C are two common pathogens causing chronic hepatitis in patients with end-stage renal disease (ESRD). With the acceptance of hepatitis B s antigen (HBsAg) screening, infected patients have been identified and isolated over the past 20 years. Consequently, hepatitis B is now being seen less frequently in dialysis units. Even though hepatitis B has become less of a problem, non-A, non-B hepatitis has been recognized as a significant problem since 1979. With the availability of serological testing for hepatitis C virus (HCV), more specific information is now available in regard to HCV infection in dialysis patients. The prevalence of anti-HCV in haemodialysis (HD) patients is quite variable, ranging from 5 to over 50%. Anti-HCV positivity is associated with previous blood transfusions, mode of therapy and duration of haemodialysis. In Spain and Italy, the annual seroconversion rates of HCV antibodies in dialysis patients are 2-9%; this rate was much higher in Taiwan (15%). Whether patients with HCV infection should be identified and isolated during HD treatment is an issue of controversy. Transplantation is associated with increases in hepatitis B virus (HBV) replicative markers. The survival disadvantage in HBsAg-positive recipients usually did not become apparent until 8 years after transplantation. Hepatitis C virus-infected renal transplant recipients are presumably in a similar situation to patients with hepatitis B, although confirmatory data are currently lacking. Coinfection of HBV and HCV may lead to aggressive liver disease and cirrhosis. A hepatitis B vaccine is recommended for all susceptible dialysis patients. Dialysis patients have lower response rates to hepatitis B vaccines than do other people. Currently, no vaccine is available for hepatitis C. To date, there are no effective treatments available for hepatitis B and hepatitis C. Combination therapy with interferon/lamivudine for hepatitis B and interferon/ribavirin for hepatitis C may offer a promise of effective control of viral replication in the future.

Hepatitis C virus: the nephrologist's view

The last 4 years have been a period of rapid expansion in our understanding of both the molecular biology and clinical significance of hepatitis C virus (HCV) infection. Initial studies using first-generation enzyme-linked immunosorbent assays suggested that the end-stage renal disease population had an exceptionally high prevalence of anti-HCV compared with asymptomatic healthy blood donors. Subsequent analyses with second-generation assays and polymerase chain reaction techniques to detect viremia confirmed these earlier studies. Considering the prevalence of HCV within the dialysis population, it comes as no surprise that several studies confirmed HCV as the leading cause of non-A, non-B hepatitis among renal allograft recipients. Furthermore, transmission of HCV by transplantation of a kidney from an HCV-infected organ donor has been unequivocally demonstrated. The natural history of HCV infection in the immunosuppressed allograft recipient and its impact on long-term patient outcome are still being analyzed. Finally, HCV has been associated with essential mixed cryoglobulinemia and several histologic patterns of immune complex glomerulonephritis, including membranous and membrano-proliferative glomerulonephritis. Although HCV antigen-antibody complexes have not been demonstrated in the kidney, the marked decrease in proteinuria following clearance of HCV RNA with interferon alpha-2b therapy suggests an etiologic role for HCV in these glomerular diseases. Furthermore, the demonstration of HCV RNA in the cryoprecipitate of patients with essential mixed cryoglobulinemia and a beneficial response to treatment with interferon alpha-2b also suggest a role for HCV in the pathogenesis of these clinical syndromes.

Lower prevalence of anti-hepatitis C antibody in dialysis and renal transplant patients in Ireland

It is well recognised that haemodialysis and renal transplant patients are at increased risk of developing non-A, non-B hepatitis. Recently the genome of hepatitis C virus (HCV), the major causative agent for non-A, non-B hepatitis, has been isolated. Anti-HCV seroprevalence was assessed in all haemodialysis patients (266) in Ireland who in March 1990 had been dialysed for at least 6 months. For comparative purposes, 272 patients who had functioning renal transplants for greater than 6 months were also studied. Potential risk factors such as age, number of blood transfusions and time on dialysis were evaluated. The prevalence of HCV infection as evidenced by antibody detection was only 1.1% for transplant and 1.7% for haemodialysis patients. This compares to a reported incidence of between 10% and 50% found elsewhere. Two of the 5 anti-HCV positive haemodialysis patients and 2 of the 3 transplant patients had biochemical evidence of liver disease. From stored sera it was possible to ascertain when patients acquired HCV. Whether the very low prevalence of anti-HCV in Irish patients is due to the low prevalence of the virus in the general population, the policy of non reimbursement of blood donors, genetic or other factors, remains to be determined.