Effect of concurrent acute infection with hepatitis C virus on acute hepatitis B virus infection

Progression of hepatic fibrosis in patients with hepatitis C: a prospective repeat liver biopsy study

BACKGROUND

The natural history of hepatitis C virus (HCV) infection remains uncertain. Previous data concerning rates of progression are from studies using estimated dates of infection and single liver biopsy scores. We prospectively studied the rate of progression of fibrosis in HCV infected patients by repeat liver biopsies without intervening treatment.

PATIENTS

We studied 214 HCV infected patients (126 male; median age 36 years (range 5-8)) with predominantly mild liver disease who were prospectively followed without treatment and assessed for risk factors for progression of liver disease. Interbiopsy interval was a median of 2.5 years. Paired biopsies from the same patient were scored by the same pathologist.

RESULTS

Seventy of 219 (33%) patients showed progression of at least 1 fibrosis point in the Ishak score; 23 progressed at least 2 points. Independent predictors of progression were age at first biopsy and any fibrosis on first biopsy. Factors not associated with progression were: necroinflammation, duration of infection, alcohol consumption, alanine aminotransferase levels, current or past hepatitis B virus infection, ferritin, HCV genotype, and steatosis or iron deposition in the initial biopsy.

CONCLUSIONS

One third of patients with predominantly mild hepatitis C showed significant fibrosis progression over a median period of 30 months. Histologically, mild hepatitis C is a progressive disease. The overall rate of fibrosis progression in patients with hepatitis C was low but increased in patients who were older or had fibrosis on their index biopsy. These data suggest that HCV infection will place an increasing burden on health care services in the next 20 years.

Cost-effectiveness of nucleic acid test screening of volunteer blood donations for hepatitis B, hepatitis C and human immunodeficiency virus in the United States

BACKGROUND AND OBJECTIVES

The aim of this study was to examine the cost-effectiveness of adding nucleic acid testing (NAT) to serological (antibody and antigen) screening protocols for donated blood in the United States (US) with the purpose of reducing the risks of transfusion-transmission of hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV).

MATERIALS AND METHODS

The costs, health consequences and cost-effectiveness of adding either minipool or individual-donor NAT to serological screening (SS) testing were estimated using a decision-analysis model.

RESULTS

With the given modelling assumptions, adding minipool NAT would avoid an estimated 37, 128 and eight cases of HBV, HCV and HIV, respectively, and save approximately 53 additional years of life and 102 additional quality adjusted life years (QALYs) compared with SS, at a net cost of $154 million. SS + minipool NAT - p24 compared with SS alone resulted in an incremental cost-effectiveness ratio of $1.5 million per QALY gained (range in sensitivity analysis $1.0-2.1 million per QALY gained) in this US analysis.

CONCLUSIONS

The cost effectiveness of adding NAT screening is outside the typical range for most healthcare interventions, but not for established blood safety measures.

Incidence and estimated rates of residual risk for HIV, hepatitis C, hepatitis B and human T-cell lymphotropic viruses in blood donors in Canada, 1990-2000

BACKGROUND

Since 1990, the Canadian Red Cross Society and Canadian Blood Services have been testing blood donors for hepatitis C virus (HCV) antibody and HCV nucleic acids and have supplemented HIV antibody testing with p24 antigen testing. We report trends in the incidence of blood-transmissible viral markers and estimates of the risk of undetected infection in donors over the last decade.

METHODS

We extracted anonymous donor and blood-transmissible disease information from the Canadian Blood Services National Epidemiology Donor Database for 8.9 million donations from 2.1 million donors between June 1990 and December 2000. The risk of transfusion-transmitted infection (or "residual risk") refers to the chance that an infected donation escapes detection because of a laboratory test's window period (i.e., the time between infection and detection of the virus by that test). We determined the probability of residual contamination of a unit of blood after testing by using the incidence/window period model, which is based on the incidence of infection in repeat donors and the window period for each laboratory test. The viral markers evaluated in the study were HIV, HCV, hepatitis B virus (HBV) and human T-cell lymphotropic virus (HTLV).

RESULTS

Except for HBV, the transmissible-disease rates of the other evaluated viruses decreased over the study period, with less of a decrease for HTLV. In 2000, the transmissible-disease-positive rate per 100 000 donations was 0.38 for HIV, 16.83 for HCV, 12.40 for HBV and 1.77 for HTLV. The residual risk of HIV, HCV and HTLV decreased over the study period; the residual risk of HBV fluctuated throughout the decade. The current residual risk per million donations is 0.10 for HIV, 0.35 for HCV, 13.88 for HBV and 0.95 for HTLV.

INTERPRETATION

Except for HBV, the estimated risk of undetected infection (residual risk) has decreased over time. The rates of transmissible disease and the probability of undetected transmission of infection are at par with, if not lower than, those reported for other industrialized countries.

HCV viral load in anti-HCV-reactive donors and infectivity for their recipients

BACKGROUND

An attempt has been made to determine the minimum level of HCV nucleic acid in donors associated with infection of recipients. This is important for considerations about assay sensitivity, use of minipool versus single-donation testing, and continued use of serologic testing.

STUDY DESIGN AND METHODS

A total of 5387 specimens from the Transfusion-Transmitted Viruses Study in the 1970s were screened for antibody to HCV (anti-HCV). The outcome in recipients of seroreactive donations was examined for viremia and seroconversion. Present techniques for both groups included third-generation EIA, RIBA, quantitative RT-PCR assay, and transcription-mediated amplification (TMA) assay.

RESULTS

A total of 156 recipients of components from 180 anti-HCV-reactive donors were identified. One-hundred seven of these were HCV-naïve before transfusion and received a single, confirmed seropositive unit; 94 (88%) became infected. Eighty-five recipients had donors whose HCV RNA level was quantifiable by RT-PCR (range, 182-3,310,000 copies/mL). Eighty-three (98%) seroconverted. Of the remaining 22, a total of 10 received units positive for HCV RNA detected only by TMA; all 10 recipients seroconverted. Of the remaining 12 recipients of anti-HCV+, TMA-negative units, 1 recipient seroconverted.

CONCLUSIONS

High rates of transmission were seen at all levels of viremia, and one donor transmitted with undetectable levels in the TMA assay. Current HCV RNA testing will therefore not interdict all infectious units, even with single-donation testing, and serologic screening must be continued.

Estimation of the risk of hepatitis B virus, hepatitis C virus and human immunodeficiency virus infectious donations entering the blood supply in England, 1993-2001

BACKGROUND AND OBJECTIVES

The frequency of hepatitis B virus (HBV), hepatitis C virus (HCV) or human immunodeficiency virus (HIV) infectious donations entering the blood supply in England is too low to monitor using observational studies. The expected frequency of infectious donations can be estimated and these estimates may be used to contribute to monitoring of blood safety and used in the design of strategies to decrease the risk of transfusion-transmitted infections.

MATERIALS AND METHODS

The prevalence and incidence of hepatitis B surface antigen (HBsAg), and antibodies to HCV and HIV (anti-HCV and anti-HIV, respectively) in donors in England, between 1993 and 2001, were used together with data about the length of negative 'window-periods' of current assays for each of these markers and data about test performance, to estimate the number of infectious donations that enter the blood supply. The risks were calculated separately for donations from new donors and from repeat donors, and for the three time periods 1993-95, 1996-98 and 1999-01.

RESULTS

The estimated frequency of infectious donations entering the blood supply in England, between 1993 and 2001 was 1 in 260,000 for HBV and 1 in 8 million for HIV. For HCV, the frequency of infectious donations was 1 in 520,000 during 1993-98 and fell to 1 in 30 million during 1999-2001 when all donations were tested for HCV RNA. The frequency of HBV- and HCV-infectious donations entering the blood supply fell over these 9 years: the frequency of HIV-infectious donations remained essentially unchanged. The risk from donations from new donors was found to be approximately sevenfold higher than the risk from donations from repeat donors.

CONCLUSIONS

The risks of HBV-, HCV- or HIV-infectious donations entering the blood supply in England are very low, and have decreased since 1993. Although the accuracy of these estimates is imperfect, mainly owing to uncertainty in some assumptions and to small numbers of infections, they provide some quantification of the risk of HBV, HCV or HIV transmission by transfusion, and allow comparison of the magnitude of these risks for each infection and over time. The methods we have used have been developed and improved from previously published methods.

Acute hepatitis B and C virus coinfection: a virological and clinical study of 3 cases

We report the virological interaction in, clinical presentation of, and course of disease observed in 3 male injection drug users with acute hepatitis B virus (HBV) and hepatitis C virus (HCV) coinfection. In all 3 cases, HBV infection presented first and quickly resolved. Diagnosis of acute HBV/HCV coinfection requires a long follow-up period with careful observation.

HBV superinfection in hepatitis C virus chronic carriers, viral interaction, and clinical course

We enrolled 44 patients with hepatitis B virus (HBV) acute infection, 21 anti-hepatitis C virus (HCV)-positive for at least 1 year (case BC group), 20 anti-HCV-negative (control B group), and 3 with HBV/HCV acute concurrent infection. For each case BC, a subject with chronic HCV infection alone was selected (control C group). At the first observation, 85.7% of patients in case BC group and 85% of those in control B group were HBV-DNA-positive (polymerase chain reaction [PCR]), with a similar trend towards a decrease and negativization in about 20 days; in the case BC group, seroconversion to antibody to hepatitis B e antigen (anti-HBe) was more rapid. HCV-RNA (PCR) was undetectable in all case BC patients but 1, who shortly became negative, whereas 85.7% of subjects in control C group were positive (P <.001). Severe acute hepatitis was more frequent in the case BC group than in the control B group (28.6% vs. 0%, P <.05). Of the 14 patients in the case BC group and of the 16 in the control B group followed up for more than 6 months, 1 in the first and 1 in the second group became hepatitis B surface angiten (HBsAg) chronic carriers. Of the 13 patients in case BC group who recovered, 1 cleared both anti-HCV and HCV-RNA, 6 became HCV-RNA-positive, and 6 remained HCV-RNA-negative. In patients with HBV/HCV acute concurrent infection, HBV-DNA became undetectable in 15 days, and HCV-RNA and anti-HCV became positive at days 30 and 45, respectively; these patients developed HCV-RNA-positive chronic hepatitis. In conclusion, HBV superinfection in chronic HCV carriers has a severe clinical course and strongly and persistently depresses HCV.

Assessing the accuracy of three viral risk models in predicting the outcome of implementing HIV and HCV NAT donor screening in Australia and the implications for future HBV NAT

BACKGROUND

Risk modeling is now the most practical method of estimating the residual risk of viral transmission in developed countries. One method of assessing the accuracy of a risk model is to measure the observed against the predicted outcome after implementing a new screening method. The primary objective of this paper is to assess the accuracy of three published models in predicting the impact of implementing HIV and HCV NAT in Australia.

STUDY DESIGN AND METHODS

Viral screening data on Australian donors for 2000 and 2001 were retrospectively analyzed. The data were applied to the three models to estimate the risk of transmission and predicted NAT yield for HIV, HCV, and HBV.

RESULTS

The median risk estimates for the three models were 1 in 3,415,000 for HIV NAT, 1 in 911,000 for HCV NAT, and 1 in 483,000 for HBsAg. The predicted NAT yield for the three models ranged from 0.17 to 0.30 per million donations for HIV, 1.20 to 5.55 for HCV, and 0.47 to 1.01 for HBV. The observed NAT yield was not significantly different from the expected yield with any of the three models for either HIV or HCV.

CONCLUSIONS

First, the residual risk in Australian donors is small in comparison with other transfusion complications and comparable to or lower than the risk in US and European nonremunerated donors. Second, mathematical risk modeling has sufficient precision to be used as a predictive tool for risk-benefit assessments of novel screening procedures. Finally, in relation to the case for implementing HBV NAT and/or anti-HBc in Australia, we conclude that at present, there is inadequate information about our donor population to perform an evidence-based risk-benefit analysis.

Trends in residual risk of transfusion-transmitted viral infections in France between 1992 and 2000

BACKGROUND

Monitoring trends in residual risks of transfusion-transmitted viral infections (HIV, HTLV, HBV, and HCV) is important to assess improvements in blood safety. In France, theses trends were analyzed between 1992 and 2000.

STUDY DESIGN AND METHODS

As risk is predominantly associated with the window period, residual risks were estimated by multiplying incidence rates by the durations of the window periods. Incidence rates were calculated from the data collected by the blood transfusion centers belonging to the Transfusion-Transmissible Agents Working Group, which currently collects more than 50 percent of the 2.5 million blood samples donated each year in France.

RESULTS

Trend analysis showed a significant decrease in residual risks for HCV (p = 0.01) and HBV (p < 0.001). Although residual risks decreased for HIV and HTLV, the trends were not significant. In 1998 through 2000, residual risks were estimated to be 1 in 470,000 donations for HBV, 1 in 860,000 for HCV, 1 in 1,370,000 for HIV, nil for HTLV, and 1 in 250,000 for the four viruses combined.

CONCLUSIONS

In France, the current risk of a blood recipient becoming infected with a retrovirus or a hepatitis virus is extremely low. The implementation of NAT in July 2001 is predicted to reduce the residual risk to 1 in 2,700,000 donations for HIV and 1 in 8,300,000 for HCV.

Hepatitis C virus infection among Brazilian hemophiliacs: a virological, clinical and epidemiological study

We determined and analyzed risk factors of hepatitis C virus (HCV)-infected Brazilian hemophiliacs according to their virological, clinical and epidemiological characteristics. A cross-sectional and retrospective study of 469 hemophiliacs was carried out at a Brazilian blood center starting in October 1997. The prevalence of HCV infection, HCV genotypes and factors associated with HCV RNA detection was determined. The seroprevalence of anti-HCV antibodies (ELISA-3.0) was 44.6% (209/469). Virological, clinical and epidemiological assessments were completed for 162 positive patients. There were seven (4.3%) anti-HCV seroconversions between October 1992 and October 1997. During the same period, 40.8% of the positive anti-HCV hemophiliacs had abnormal alanine transaminase (ALT) levels. Plasma HCV RNA was detected by nested-RT-PCR in 116 patients (71.6%). RFLP analysis showed the following genotype distribution: HCV-1 in 98 hemophiliacs (84.5%), HCV-3 in ten (8.6%), HCV-4 in three (2.6%), HCV-2 in one (0.9%), and not typeable in four cases (3.4%). Univariate analysis indicated that older age (P = 0.017) and abnormal ALT levels (P = 0.010) were associated with HCV viremia, while the presence of inhibitor antibodies (P = 0.024) and HBsAg (P = 0.007) represented a protective factor against the presence of HCV RNA. These findings may contribute to a better understanding of the relationship between HCV infection and hemophilia.

An estimate of the current risk of transmitting blood-borne infections through blood transfusion in Italy

We conducted a retrospective cohort study to estimate the incidence of major blood-borne agents among Italian blood donors and calculated the risk of infection among blood recipients using the 'incidence/window period model'. The study was conducted among 46 180 blood donors enrolled in six blood centres between 1994 and 1999. During follow-up, seven new infections were confirmed: three donors seroconverted for anti-human immunodeficiency virus (HIV); two for anti-hepatitis C virus (HCV); and two showed hepatitis B surface antigen (HBsAg) reactivity; no cases of syphilis were observed. The incidence rates per 100 000 person/years were: 4.06 (95% CI: 0.82-11.85) for HIV; 2.41 (95% CI: 0.29-8.70) for HCV; and 2.70 (95% CI: 0.32-9.77) for HBsAg; the incidence for total hepatitis B virus (HBV) infection was 9.77 per 100 000 person/years (95% CI: 1.16-35.36). The estimated risk of an infectious blood unit not being detected was: 2.45 (95% CI: 0.13-12.33) per 1 million units for HIV; 4.35 (95% CI: 0.30-22.39) for HCV; and 15.78 (95% CI: 1.16-84.23) for HBV. Overall, an estimated 22.58 per 1 million units are infected. In Italy, the risk of transfusion-transmitted infections is low and is similar to that in other western countries. The introduction of new more sensitive screening tests could reduce the residual risk of transfusion-transmitted infection by 40-80%.

Impact of hepatitis B and C on graft loss and mortality of patients after kidney transplantation

BACKGROUND

Mortality or graft loss after renal transplantation might be influenced by hepatitis virus infection.

METHODS

Sera from time of transplantation of 927 renal transplant recipients were tested for hepatitis C (HCV) and hepatitis B virus (HBV) in order to investigate the impact of hepatitis virus infection on graft loss and mortality over an observation period of 20 yr.

RESULTS

One hundred and twenty three of 927 patients were HCV positive, 30 patients HBV positive and seven patients HBV and HCV positive. The observation period was 9.2 +/- 4.4 yr. Mortality was significantly higher in patients with hepatitis B (p = 0.0005), as well as in patients with concomitant B and C hepatitis (p < 0.0001) and in those who acquired HCV infection after transplantation (n = 30, p = 0.0192) compared with non-infected patients. Patients with replicating HBV infection (HBeAg positive) had the worst prognosis (p < 0.0001). In the multivariate analysis the presence of HBeAg (p < 0.0001), patients' age (p < 0.0001) and HCV infection after transplantation (p = 0.0453) were predictors for death. Graft survival was significantly shorter in patients with concomitant hepatitis B and C (p = 0.0087) as well as in HBeAg positive patients (p = 0.002). HCV infection or HBs antigenemia did not have a significant impact on graft survival compared with non-infected patients.

CONCLUSION

HCV infection after transplantation is associated with a high mortality whereas chronic HCV infection before trans plantation does not have a significant impact on mortality. Patients with replicating HBV infection or concomitant HBV and HCV infection have a high risk of graft loss and mortality.

The risks of transfusion-transmitted infection: direct estimation and mathematical modelling

Direct measurement of the risk of transfusion-transmitted infection (TTI) is practical and accurate only if the level of risk is high. Historically, studies that established frozen repositories of transfusion recipient and/or blood donor samples were important in establishing the risk of many TTI agents, including the human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV). However, given the current very low risk of TTI, mathematical modelling is necessary to estimate the magnitude of such a risk. For agents for which routine blood donor screening is performed, most of this risk comes from transfusion of units collected in the window period between donor infection and a positive blood screening assay. The incidence/window period model has been used to estimate the magnitude of such risks (of the order of 1:100 000 to 1:1 000 000) and for predicting the extent of risk reduction that can be expected with implementation of new tests. Direct estimation and mathematical modelling approaches are both important tools for future assessment of potential, new or emerging TTI agents.

Hepatitis C virus infection: co-infection with HIV and HBV

Hepatitis C shares common routes of infection with hepatitis B (HBV) and the human immunodeficiency virus (HIV). It is, therefore, not surprising to find that some patients with HCV are co-infected with either HIV and/or HBV. Until recently, the effects of HIV on HCV infection have not been investigated--sadly patients with HIV died long before their liver disease became problematic. However, the development of successful therapies for HIV have led to dramatic improvements in life expectancy for patients infected with this virus and in these patients, with well controlled HIV, it is becoming clear that hepatitis C may lead to the early onset of advanced liver disease. The optimal treatment for these patients is unknown but it seems likely that combination antiviral therapy will be required. The effects of HBV on HCV are also beginning to be investigated and, again, it is clear that co-infection leads to more aggressive liver disease with the two viruses interacting in poorly defined ways to increase the rate of hepatic fibrosis. Management of combined HCV/HBV infection is still under investigation and will probably involve combination therapy.

Replication status and histological features of patients with triple (B, C, D) and dual (B, C) hepatic infections

In patients with multiple hepatotropic viral infections (B and C, or B, C and D), the reciprocal influence of each virus remains controversial. The aims of this study were twofold: first, to determine the impact of multiple infection on the replication status of B, C and D viruses and on histological features; and second, to compare patients with multiple infection to patients infected only with the hepatitis C virus (HCV). We retrospectively included 50 patients with multiple infection and 50 control HCV patients, who were matched on independent factors associated with fibrosis, such as age, gender, alcohol consumption and duration of infection. The replication status of hepatitis B virus (HBV), HCV and hepatitis D virus (HDV), and histological lesions, were determined. In patients with multiple infection, HCV RNA was present less frequently (44% vs 98%, P < 0.001) and the prevalence of cirrhosis was higher (35% vs 8%, P < 0.001). Among patients with triple infection (n = 16), HBV replication was observed in 25%, HCV RNA was detectable in only two (P < 0.0001) and HCV viremia was significantly lower than in the matched HCV patients (0 vs 54.7, P < 0.0001). Among patients with dual infection (n = 34), HCV RNA was present less frequently in those with serological markers of active HBV infection than in those without (30% vs 79%, P = 0.01). Hence, multiple infection is associated with a decrease of HCV replication. Cirrhosis seems to be more frequently observed in patients with multiple infection. In patients with triple infection, serum HCV RNA and markers of HBV replication were absent in 80%, suggesting that HDV acts as a dominant virus. In patients with dual infection, HBV and HCV exert an alternative, dominant replication.

Dual or Single Hepatitis B and C Virus Infections in Childhood Cancer Survivors: Long-Term Follow-Up and Effect of Interferon Treatment

We conducted a long-term prospective study of 89 cancer survivor children who had acquired hepatitis B virus (HBV) and/or hepatitis C virus (HCV) during treatment for neoplasia, the aim being to evaluate the natural history of the diseases and the effect of interferon (IFN) treatment. Patients were followed up for a median period of 13 years (range, 8 to 20); 46 were infected by HBV, 11 by HCV, and 32 coinfected by HBV and HCV. A spontaneous clearance of hepatitis B surface antigen (HBsAg) occurred more frequently in coinfected patients (19%) than in the HBV-infected (2%; P = .004), with an annual seroconversion rate of 2.1% and 0.2%, respectively (P= .008). Loss of hepatitis Be antigen (HBeAg) occurred in 44% of coinfected and in 28% of HBV-infected patients. Clearance of serum HCV-RNA was observed in 34% and 9%, respectively, of coinfected and HCV-infected patients. Seventeen HBV-infected, 4 HCV-infected, and 16 coinfected patients received -IFN treatment. In the HBV group, 6 patients (35%) cleared serum HBV DNA and seroconverted to anti-HBe; in the HCV-group, none cleared HCV-RNA. In the coinfected group, 1 patient cleared both HBV DNA and HCV-RNA, 6 patients cleared serum HCV-RNA alone, and 1 only HBV DNA and HBeAg. Overall, the diseases showed a mild histological course with no evidence of liver cirrhosis. A reciprocal interference on viral replication between HBV and HCV may occur in coinfected patients. Treatment seems to be effective for selected cases and is justified in view of the uncertain prognosis of the disease in these patients.

Dual or Single Hepatitis B and C Virus Infections in Childhood Cancer Survivors: Long-Term Follow-Up and Effect of Interferon Treatment

We conducted a long-term prospective study of 89 cancer survivor children who had acquired hepatitis B virus (HBV) and/or hepatitis C virus (HCV) during treatment for neoplasia, the aim being to evaluate the natural history of the diseases and the effect of interferon (IFN) treatment. Patients were followed up for a median period of 13 years (range, 8 to 20); 46 were infected by HBV, 11 by HCV, and 32 coinfected by HBV and HCV. A spontaneous clearance of hepatitis B surface antigen (HBsAg) occurred more frequently in coinfected patients (19%) than in the HBV-infected (2%; P = .004), with an annual seroconversion rate of 2.1% and 0.2%, respectively (P= .008). Loss of hepatitis Be antigen (HBeAg) occurred in 44% of coinfected and in 28% of HBV-infected patients. Clearance of serum HCV-RNA was observed in 34% and 9%, respectively, of coinfected and HCV-infected patients. Seventeen HBV-infected, 4 HCV-infected, and 16 coinfected patients received -IFN treatment. In the HBV group, 6 patients (35%) cleared serum HBV DNA and seroconverted to anti-HBe; in the HCV-group, none cleared HCV-RNA. In the coinfected group, 1 patient cleared both HBV DNA and HCV-RNA, 6 patients cleared serum HCV-RNA alone, and 1 only HBV DNA and HBeAg. Overall, the diseases showed a mild histological course with no evidence of liver cirrhosis. A reciprocal interference on viral replication between HBV and HCV may occur in coinfected patients. Treatment seems to be effective for selected cases and is justified in view of the uncertain prognosis of the disease in these patients.

Clearance of HCV RNA in a chronic hepatitis C virus-infected patient during acute hepatitis B virus superinfection

The routes of hepatitis B virus and hepatitis C virus transmission are quite similar and coexistence of both viruses in one patient is not a rare phenomenon. Until now, the natural course of liver diseases induced by coinfections has not been well documented and the mechanisms of interaction between the two viruses and the human host have not been fully clarified. We report the case of a patient suffering from chronic hepatitis due to hepatitis C virus who developed an acute hepatitis B virus superinfection. Serum hepatitis C virus ribonucleic acid became undetectable by reverse transcriptase/polymerase chain reaction at diagnosis of acute hepatitis B virus infection. At the same time, there was a striking increase in the serum concentrations of the antibodies against C22 and C33c hepatitis C virus antigens. Four months after clinical resolution of the acute hepatitis, hepatitis B surface antigen was undetectable in serum and three months later antibodies against hepatitis B surface antigen appeared. Two years after acute hepatitis B virus infection, the patient has had no relapse of markers for viral replication of hepatitis B virus. Transaminases are within the reference range and hepatitis C virus ribonucleic acid is undetectable in both serum and liver tissue. We hypothesize that acute hepatitis B virus infection stimulated a specific humoral response against hepatitis C virus as well as triggering non-specific defense mechanisms which finally eliminated both viruses.

[Practical repercussions of 3 years of experience of national hemovigilance on the subject of viral complications]

The residual risk of transmitting viral infections by transfusion of screened blood is mainly linked to donations occurring in the window period. Using a mathematical model, a French study, including a 3 year period of blood donations (1994-1996), was performed by the Hepatitis Virus and Retrovirus working groups of the French Society of Blood Transfusion. The residual risk in France was estimated as follows: for HIV, 1 in 1 million (IC 95% = 1/10 million to 1/295,000), for HTLV 1 in 5 million (IC 95% = 0 to 1/625,000), for VHC 1 in 200,000 (IC 95% = 1/530,000 to 1/97,000), for VHB 1 in 180,000 (IC 95% = 1/560,000 to 1/66,000). Based on these estimations, the number of recipients possibly contaminated should have been seven for HIV, one or two for HTLV, 35 for VHC, 40 for VHB for a 3 year period. These 83 to 84 theoretically contaminated recipients are not in accordance with the six recipients contaminated by a blood product (two with HIV, one with VHC, three with VHB) that were reported to the National Haemovigilance Unit of the Agence Française du Sang. This observed difference may be explained by an overestimated calculated risk (the whole window period is not infectious), or by an underestimation of real post-transfusion contamination due to a lack of exhaustive notifications. However, a national database of post-tranfusion contamination is useful to approach the real residual risk. Therefore, efforts to continue the recipient follow-up have to be encouraged.

The risk of transmitting HCV, HBV or HIV by blood transfusion in Victoria

OBJECTIVE

To report the incidence rate of hepatitis B virus (HBV), hepatitis C virus (HCV) and HIV in Victorian repeat blood donors and to derive the residual risk of transmission of the viruses by screened blood transfusion.

DESIGN

The interval from the previous whole blood donation was extracted retrospectively from Victorian Red Cross Blood Bank records for each of the 358332 repeat donations given between March 1994 and December 1995. Records of repeat donors found positive for the viruses in this period were traced to the previous seronegative donation and accepted if screened by the same test. For each virus, the number of previous donations screened by the same test was calculated and the sum of all donation intervals used to derive the incidence of infection in the repeat donor population. Published intervals after infection (when a donation can be infective although seronegative) were used to calculate the risk of release of a seronegative unit which would be infective.

PARTICIPANTS AND SETTING

Homologous blood donors at the Red Cross Blood Bank of Victoria.

MAIN OUTCOME MEASURES

Incidence rate of HBV, HCV and HIV in regular blood donors and risk of infective donations being seronegative.

RESULTS

The incidence of infection in repeat donors was: HBV: 1.67 per 100000 person-years; HCV: 1.89 per 100000 person-years; and HIV: 1.31 per 100000 person-years. The risk of a seronegative repeat donation being infective was: HBV: 2.71 per million donations (adjusted to 6.45 to account for viraemias which remain seronegative); HCV: 4.27 per million donations; and HIV: 0.79 per million donations.

CONCLUSION

The risk of transmitting HCV, HBV or HIV by repeat blood donors is low and compares favourably with overseas data. Repeat donors have an incidence rate of HIV and HBV comparable to that of the general population, but the incidence rate of HCV is lower for repeat donors than in the general population.

New quantitative assay of hepatitis B and C viruses by competitive PCR using alternative internal sequences

A competitive PCR was developed for quantitation of hepatitis B virus (HBV) DNA and hepatitis C virus (HCV) RNA, alternatively, using only two constructions containing both priming sites. DNAs corresponding to the HBV-S gene and the HCV-5' non-coding region were introduced into distinct plasmids. HBV plasmid was used as a standard for HBV-DNA quantitation, in competition with the HCV plasmid as internal control. HBV and HCV plasmids also served as template for transcription of HBV-RNA, and HCV-RNA, which was used as internal control and standard, respectively, in competition for HCV-RNA quantitation. The analyzed samples for HBV and HCV quantitation were processed in the same way in competition with the internal controls and to the respective calibration curves obtained by serial dilutions of the mimic standard. This method showed very good specificity and sensitivity, allowing absolute quantitation in a large linear range from 5 viral genomic copies per assay up to 10(6) copies, in sera of chronically HBV and HCV infected patients, as well as in supernatants of cell cultures inoculated with these viruses.

The occurrence of hepatitis B and C viruses in Pakistani patients with chronic liver disease and hepatocellular carcinoma

To study the occurrence of hepatitis B virus (HBV) and hepatitis C virus (HCV) in patients with chronic liver disease (CLD) and hepatocellular carcinoma (HCC) in Pakistan, blood samples from 105 sequential patients with biopsy-proven CLD (n = 82) and HCC (n = 23) were tested for HBV and HCV markers. Of the 105, 87 (83%) had evidence of hepatitis B exposure, 58 (55%) were positive for hepatitis B surface antigen (HBsAg), 23 (22%) had hepatitis C antibodies and 25 (24%) had detectable HCV RNA. Significantly more patients with HCC had evidence of HBV exposure in the absence of HCV markers (49/82 vs. 20/23, odds ratio 4.49, 95% CI 1.17-25.16). The proportion of patients positive for HBsAg with no HCV markers was also significantly higher in the HCC group (34/82 vs. 18/23, odds ratio 5.08, 95% CI 1.59-18.96). There were more patients with only HCV markers in the CLD group than the HCC group but the difference was not statistically significant (19/82 vs. 1/23, odds ratio 6.63, 95% CI 0.93-288.01). A modified non-isotopic restriction fragment length polymorphism study on PCR products was used to investigate the epidemiology of HCV genotypes in Pakistan. Due to depletion of the initial samples, a second series of specimens collected one year afterwards was used. Fifteen out of 40 samples had amplifiable product and all were identified as type 3. A commercial serological typing method on the same samples also confirmed that type 3 was the predominant HCV genotype in Pakistan.

The risk of transfusion-transmitted viral infections. The Retrovirus Epidemiology Donor Study

BACKGROUND

Accurate estimates of the risk of transfusion-transmitted infectious disease are essential for monitoring the safety of the blood supply and evaluating the potential effect of new screening tests. We estimated the risk of transmitting the human Immuno-deficiency virus (HIV), the human T-cell lymphotropic virus (HTLV), the hepatitis C virus (HCV), and the hepatitis B virus (HBV) from screened blood units donated during the window period following a recent, undetected infection.

METHODS

Using data on 586,507 persons who each donated blood more than once between 1991 and 1993 at five blood centers (for a total of 2,318,356 allogeneic blood donations), we calculated the incidence rates of seroconversion among those whose donations passed all the screening tests used. We adjusted these rates for the estimated duration of the infectious window period for each virus. We then estimated the further reductions in risk that would result from the use of new and more sensitive viral-antigen or nucleic acid screening tests.

RESULTS

Among donors whose units passed all screening tests, the risks of giving blood during an infectious window period were estimated as follows: for HIV, 1 in 493,000 (95 percent confidence interval, 202,000 to 2,778,000); for HTLV, 1 in 641,000 (256,000 to 2,000,000); for HCV, 1 in 103,000 (28,000 to 288,000); and for HBV, 1 in 63,000 (31,000 to 147,000). HBV and HCV accounted for 88 percent of the aggregate risk of 1 in 34,000. New screening tests that shorten the window periods for the four viruses should reduce the risks by 27 to 72 percent.

CONCLUSIONS

The risk of transmitting HIV, HTLV, HCV, or HBV infection by the transfusion of screened blood is very small, and new screening tests will reduce the risk even further.

Transfusion-transmitted disease

Many patients with haemophilia are infected with viruses, due to treatment with blood products--particularly from large pool clotting factor concentrates before 1985. AIDS in haemophilic patients was first described in 1982 and it has significantly reduced the life expectancy of these patients. Although no new sero-conversions have occurred since 1986, management of HIV in haemophilia remains a clinical challenge. Transfusion-associated hepatitis was recognized in 1943, and it is now an important complication of haemophilia treatment. Vaccination against HAV is recommended. Intensively-treated older haemophilic patients usually have serological evidence of HBV infection. HBV transmission has been stopped, but hepatitis B vaccination is still practised, because HDV requires HBV for propagation. Many patients are infected with HCV: before 1985 almost all patients who received clotting factor concentrate developed non-A, non-B hepatitis, now recognized as HCV. Treatment strategies are being developed for HCV in haemophilic patients. Parvo virus can be transmitted by clotting factor concentrate; it is very resistant to sterilization processes, transmission causing severe illness even in immuno-competent individuals. New blood-borne viruses responsible for sero-negative hepatitis include: GBV-A, B and C, and HGV. Although there is no link between CJD and haemophilia, there is concern about possible blood product transmission.

[Estimation of risk of virus transmission in hepatitis B and C and human retrovirus via transfusion of labile blood derivatives]

This study estimates the risk of transmitting human immunodeficiency virus (HIV), human T lymphotropic virus (HTLV), hepatitis C virus (HCV) and hepatitis B virus (HBV) from blood units using a seroconversion incidence model. Data from 13 blood transfusion centers collecting about 1 million donations per year and belonging to the Retrovirus and the Viral Hepatitis study groups were analyzed during the 3 year study period (1992-1994) for HIV, HTLV, and HBV and a 2 year study period for HCV (1993-1994). Seroconversion incidence rates were calculated and multiplied by estimates of the serological window period for each agent to obtain residual risk. The risk that an infectious donation was made during the window period was estimated to be 1 in 2 millions (95% CI: 1/10(7)-1/450000) for HTLV, 1 in 588000 (1/3 300000-1/227000) for HIV, 1 in 217000 (1/714000-1/83000) for HCV and 1 in 112000 (1/333000-1/43500) for HBV. This risk was estimated for the totality of donations collected in France for HIV and HTLV. For HIV it was the same as above (1 in 588000) and for HTLV it was much lower (1 in 7 millions).

Role of hepatitis C virus in dual and triple hepatitis virus infection

Hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis delta virus (HDV) share same transmission routes, thus dual or triple infection may occur and even persist in the same patients. A significant amount of literature has accumulated since the advent of HCV assays. It is pertinent to review and evaluate the clinical and virological significance of HCV in multiple hepatotropic viral infection. The reported series on seroprevalence of HCV indicate that HCV is found in more than 10% of HBV- or HDV-infected patients worldwide. Of the patients with dual or triple infection involving HCV, those having coreplication of viruses tend to have severe and progressive liver disease that is resistant to interferon therapy, in contrast with patients having a single virus infection. Paradoxically, dual or triple hepatitis virus infections are associated with viral interference. In particular, HCV exerts a suppressive effect on HBV and HDV and may enhance seroclearance of HBV antigens or even usurp the role of preexisting virus as the agent for continuing hepatitis. Although HBV and HDV may also suppress HCV, it appears to be less effective. These findings clearly suggest the necessity of monitoring patients with HBV or HDV infections. In view of complex dynamism of viral interaction in multiple hepatotropic virus infection, the importance of HCV assay in the clinical studies can not be overemphasized. The basic mechanisms that regulate the viral interactions, in particular the impact of HCV in dual or triple virus infections, remain to be investigated.

Hepatitis C: progress and problems

The hepatitis C virus (HCV), a single-stranded RNA virus, is the major cause of posttransfusion hepatitis. HCV isolates differ in nucleotide and amino acid sequences. Nucleotide changes are concentrated in hypervariable regions and may be related to immune selection. In most immunocompetent persons, HCV infection is diagnosed serologically, using antigens from conserved regions. Amplification of RNA may be necessary to detect infection in immunosuppressed patients. Transmission by known parenteral routes is frequent; other means of spread are less common and may represent inapparent, percutaneous dissemination. Infection can lead to classical acute hepatitis, but most infected persons have no history of acute disease. Once infected, most individuals apparently remain carriers of the virus, with varying degrees of hepatocyte damage and fibrosis ensuing. Chronic hepatitis may lead to cirrhosis and hepatocellular carcinoma. However, disease progression varies widely, from less than 2 years to cirrhosis in some patients to more than 30 years with only chronic hepatitis in others. Determinants important in deciding outcome are unknown. Alpha interferon, which results in sustained remission in selected patients, is the only available therapy. Long-term benefits from such therapy have not been demonstrated. Prevention of HCV infection by vaccination is likely to be challenging if ongoing viral mutation results in escape from neutralization and clearance.