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.     

Risk of hepatitis C virus (HCV) transmission by anti-HCV-negative blood components in Austria and Germany

In order to estimate the residual risk of transfusion-transmitted HCV infection, we have analyzed data from two transfusion centers in Austria (Vienna) and Germany (G6ttingen) from 1990 to 1995. In Vienna, the seroprevalence (RIBA-confirmed third-generation anti-HCV tests) was 0.28% in first-time donors (FTD) and the incidence of seroconversion in repeat donors (RD) was 0.049 (per 100 person years) from 1994 to 1995. In Göttingen, the prevalence of a PCR-confirmed positive third-generation anti-HCV test was 0.22% in FTDs and the incidence was 0.093 (per 100 person years). A continuous decline of the rate of anti-HCV-positive donations and donors was observed with first- and second-generation anti-HCV tests in the years 1990–1994. The introduction of the third-generation anti-HCV test resulted in increased numbers of anti-HCV positive repeat donors, mainly due to false-positive results. Only 9% of anti-HCV-positive repeat donors were either PCR positive or RIBA positive or indeterminate. Based on a mathematical model which takes (a) the window period, (b) the false-negative rate of anti-HCV tests, and (c) human and operational errors into consideration, we have calculated the residual risk of HCV infection. We used a window period of 74 days, a sensitivity of 98%, and an error rate of 0.1%. The residual risk (for third-generation anti-HCV test-negative blood components) was calculated to be 1:9000 (95% confidence interval 1:16390–1:6210) and 1:4800 (95% confidence interval 1:40000–1:1320) for Vienna and Göttingen, respectively, in 1994 and 1995. Since this conservative approach does not take the impact of ALAT screening into account, the actual risk is probably lower.     

Screening for viral markers in volunteer and replacement blood donors in West Africa

BACKGROUND AND OBJECTIVES: West Africa is a highly endemic area for viral infections. The prevalence of five viral markers was determined in Ghanaian blood donors. MATERIALS AND METHODS: Replacement and volunteer blood donors were screened using enzyme immunoassays (EIAs) for hepatitis B surface antigen (HBsAg), human immunodeficiency virus antibodies (anti-HIV), HIV p24 antigen, human T-cell lymphocytotrophic virus-I and -II antibodies (anti-HTLV-I/II) and hepatitis C virus antibodies (anti-HCV). RESULTS: HBsAg was present at an equally high frequency (15%) in young volunteer (median age 18 years) and older replacement (median age 33 years) blood donors. In contrast, the prevalence of anti-HIV and anti-HCV was significantly higher in replacement blood donors (2.4 and 0.3%, respectively, P < 0.001). HCV RNA was detected in 74 or 55% of seropositive donors, depending on the confirmatory criteria used. No p24 antigen-positive/anti-HIV-negative donations were found. The prevalence of HTLV-I/II was generally low (0.5%). CONCLUSION: All blood donations should be screened for hepatitis B virus (HBV), HIV and HCV markers.     

Variant Creutzfeldt-Jakob disease in Australian blood donors: estimation of risk and the impact of deferral strategies

BACKGROUND AND OBJECTIVES: In Australia, a policy of deferring donors who have lived in the UK for longer than 6 months between 1980 and 1996 has been instituted to reduce the theoretical risk of transmitting variant Creutzfeldt-Jakob disease (vCJD) through the blood supply. The objective of this report was to refine estimates of the possible risks and benefits of donor-deferral strategies that are aimed at avoiding transmission of vCJD. MATERIALS AND METHODS: Estimates of the effect of donor deferral on the blood supply in Australia were based on a 1998 survey of blood donors. The number of donations from donors potentially infected with vCJD and excluded by donor deferral was estimated based on published estimates of the size of the vCJD epidemic in the UK and assuming that the risk of vCJD in Australian blood donors was proportional to the time lived in the UK between 1980 and 1996. The possible increased number of blood donations that were infected with human immunodeficiency virus (HIV), hepatitis C virus (HCV) or hepatitis B virus (HBV) and made during a window period (as a result of increased donations from first-time donors) was estimated using published methods. RESULTS: A strategy of deferring donations in Australia from people who have lived in the UK for 6 months or longer, between 1980 and 1996, was estimated to result in exclusion of 5.3% of all blood donations, corresponding to 50 100 donations in 1998. It was estimated that the annual number of blood donations made by donors potentially infected with vCJD is 1.15 (range 0.02--31.1, based on the uncertainty in the UK prevalence estimate). Donor deferral was estimated to remove 0.92 (range 0.02--25.1) of these donations. Replacement of 33%, 50% and 100% of excluded donations by donations from first-time donors, was estimated to result in an increase of 0.0010, 0.0019 and 0.0044, respectively, of HIV-infected donations per year donated during the window period; in an increase of 0.021, 0.038 and 0.089, respectively, of HCV-infected donations per year; and in an increase of 0.18, 0.33 and 0.76, respectively, of HBV-infected donations per year. CONCLUSIONS: The large uncertainties involved in these analyses mean that estimates must be interpreted cautiously, but the data does suggest that donor deferral may exclude more donations from donors potentially infected with vCJD than the corresponding increase, caused by donor replacement, of window-period donations possibly infected with HIV, HCV or HBV.     

Prevalence of antibodies against hepatitis C virus among blood donors in Lebanon, 1997-2000.

Chronic hepatitis C virus (HCV) infection in many individuals is asymptomatic and the prevalence of antibodies to hepatitis C virus (anti-HCV) among blood donors in Lebanon is scarce. This study aimed to address the prevalence of anti-HCV in 8700 blood donors, the data obtained was compared to other world regions. Between 1997 and 2000, 8700 blood donors were screened for the presence of anti-HCV in their sera. Initially reactive specimens were retested in duplicate, and repeatedly positive samples were subsequently retested by a third generation microplate enzyme immunoassay. Of the 8700 blood donors screened, 51 were confirmed positive for anti-HCV, giving a prevalence rate of 0.6%. While there was no difference in anti-HCV prevalence in relation to age or gender, higher rates were seen in non-Lebanese compared to Lebanese subjects (6.17% vs. 0.48%, P < 0.001). None of the anti-HCV positive individuals had an identifiable risk factor for contracting HCV (intravenous drug user, prior transfusion, etc.), and their transaminases were comparable to anti-HCV-negative donors, suggesting that HCV-positive donors were asymptomatic. These results demonstrate low prevalence of anti-HCV among Lebanese blood donors, which was comparable to those established for Western countries.     

Evidence that anti-HBc but not HBV DNA testing may prevent some HBV transmission by transfusion

Blood donor screening for antibody to hepatitis B core antigen (anti-HBc) implemented in some countries as a surrogate marker for non-A, non-B hepatitis has been superseded by anti-HCV screening. To assess the value of anti-HBc screening for the detection of hepatitis B surface antigen-negative blood donations that might contain infectious HBV, HBV genomic detection and recipient testing were used. Blood donations were screened and confirmed by multiple anti-HBc assays. Donations containing isolated anti-HBc and those with anti-hepatitis B surface antigen (anti-HBs) level < 0.1 IU/ml were tested for the presence of HBV DNA. Recipients of previous donations from the corresponding donors during the previous 5 years were traced and tested for markers of HBV infection. Of 103 869 donations screened, 586 (0.56%) were anti-HBc positive, two of which contained HBsAg, and 413 (0.4%) had protective (>/= 0.1 IU/ml) levels of anti-HBs. Anti-HBs < 0.1 IU/ml was found in 102 of these donations (0.1%) and isolated anti-HBc in 69 (0.07%). No donations with isolated anti-HBc were HBV DNA confirmed positive. Of 278 recipients of previous donations from 171 donors at risk of HBV carriage, 12 had markers of HBV infection. Six recipients had other identified risk factors. An association with blood transfusion was considered probable in two and possible in four recipients. None of the six corresponding donors had detectable HBV DNA 6-40 months after the implicated donation. The frequency of HBV transmission by chronic carriers negative for hepatitis B surface antigen was estimated in this study to be 1 in 52,000 donations (CI 0.3-7.8/100,000) from HBsAg-negative donors. Such HBV infectious donations may not be detected by DNA amplification.     

Human immunodeficiency virus, hepatitis C and hepatitis B infections among blood donors in Germany 2000-2002: risk of virus transmission and the impact of nucleic acid amplification testing

Blood and plasma donations in Germany are collected by several institutions, namely the German Red Cross, community and hospital-based blood services, private blood centres, commercial plasma donation sites and transfusion services of the army. All blood donation centres are required to report quarterly data on infection markers to the Robert Koch Institute, thus providing current and accurate epidemiological data. The prevalence and incidence of relevant viral infections are low in the blood donor population in Germany, with a decreasing trend for hepatitis C infections in new and repeat donors since 1997. The implementation of mandatory nucleic acid amplification technique (NAT) testing for hepatitis C virus (HCV) in 1999 has markedly improved transfusion safety. HIV-NAT became mandatory in 2004 but was done voluntarily by the majority of the blood donation services before then. The potential benefit of hepatitis B virus (HBV) minipool NAT is not as clear because chronic HBV carriers with very low virus levels might donate unidentified. The residual risk of an infectious window period donation inadvertently entering the blood supply can be estimated using a mathematic model which multiplies the incidence rate by the number of days during which an infection may be present but not detectable, i.e. the length of the window period. The risk of an undetected infection without NAT testing was estimated to be 1 in 2,770,000 for HIV, 1 in 670,000 for HCV and 1 in 230,000 for HBV in 2001/2002. This contrasts with 1 in 5,540,000 for HIV, 1 in 4,400,000 for HCV and 1 in 620,000 for HBV with minipool NAT testing. This demonstrates that NAT testing can further reduce the already very small risk of infectious donations entering the blood supply.     

Estimates of the frequency of HBV, HCV, and HIV infectious donations entering the blood supply in the United Kingdom, 1996 to 2003

Several new tests have been recently introduced by the United Kingdom Blood Services to improve safety. The frequency (or risk) of hepatitis B virus (HBV), hepatitis C virus (HCV) and HIV infectious donations entering the UK blood supply during 1996-2003 has been estimated. These years span the introduction of nucleic acid testing (NAT) for HCV, HIV combination antigen and antibody test and NAT for HIV. The frequency of an infectious donation entering the blood supply due to i) the window period, ii) assay failures and iii) human and technical errors in testing and processing, was estimated. The window period risk was estimated using the incidence of infection in donors and the length of the window period for tests in use, with an adjustment for atypical inter-donation intervals in seroconverting donors. The estimated frequency of infectious donations entering the blood supply during 1996-2003 was 1.66, 0.80 and 0.14 per million for HBV, HCV and HIV respectively. HCV NAT resulted in an over 95% fall in the risk of HCV. Current usage of HIV combined antibody-antigen tests and of HIV NAT reduced the estimated risk of HIV by 10%. Since 1996, the risk of transfusion-transmitted HBV, HCV and HIV infection in the UK has been lowered by several improvements to donation testing, although the absolute reduction in risk has been small. Vigilance for errors and the affects of donor selection may be as or more important than further reductions to window periods of tests for improving blood safety with respect to HBV, HCV and HIV.     

HIV,HTLV, and Hepatitis B and C Infection in Blood Donors in Bahia,Brazil from 2008 to 2017

Although blood transfusion is an important therapeutic resource, transfusion-transmitted infections (TTIs) are still a cause for concern. Measures to mitigate this risk involve improvement of donor screening criteria and improvements in laboratory tests, especially the use of nucleic acid test (NAT). In this retrospective study we evaluated HIV, HTLV, HCV and HBV infection rates in blood donors of the Hematology and Hemotherapy Foundation of Bahia (Hemoba), Brazil, through serological and NAT results and the characteristics of donors. From February/2008 to December/2017, 777,446 blood donations were made. Most donors were male, aged 25–44 years, black and mixed race, and single or divorced. The density-type incidence (DTI; per 100,000) for each virus was 91.1 for HBV; 66.5 for HCV; 54.3 for HIV; and 33.9 for HTLV, with a decreasing trend observed over the period studied, except in the last biennium. NAT detected only 1 donor in immunological window for HIV (0.46/100,000 donations) and 3 donors in immunological window for HBV (1.8/100,000 donations). Serological positivity for all viruses studied was higher in the metropolitan region of Salvador, the state capital. Conclusion: DTI rates show a decreasing trend over the years studied, with a predominance of HBV infection. NAT allowed the detection of donors in immunological window periods, having an important role in improving transfusion safety.     

Large-Scale HCV RNA Screening in First-Time Blood Donors: The First Step Towards Genomic Screening of Blood Donations

BACKGROUND AND OBJECTIVES: Individual genomic screening for viruses in blood donations is becoming increasingly pressing as an alternative to pool testing to improve the safety of the blood supply. MATERIALS AND METHODS: To determine the feasibility and, possibly, efficacy of genomic screening for hepatitis C virus (HCV) in the blood service setting, a representative population of first-time blood donors was screened individually with a semi-automated genomic amplification assay for HCV RNA. First-time blood donors in two blood centres in the United Kingdom were screened in parallel for anti-HCV and HCV RNA by RT-PCR. RESULTS: 8, 417 serum samples were screened. A 99.95% specificity was observed and one anti-HCV-positive, HCV-RNA-positive donation was found. No seronegative HCV-RNA-positive donations were detected. CONCLUSIONS: These results are consistent with the low prevalence of HCV infection in blood donors from the London area and demonstrate the high level of performance of the individual genomic screening method used in this study. When fully automated, such a method would be a highly suitable candidate for routine, automated genomic screening of HCV and, subsequently, of other pathogenic blood-borne viruses.     

Transmission of Hepatitis C Virus by Anti-HCV-Negative Blood Transfusion: Case Report

Acute posttransfusion hepatitis C was reported in a recipient of 3 units of red cells. The recipient became acutely icteric 6 weeks after transfusion, and HCV infection was diagnosed. Stored serum samples of the 3 implicated donations, which were negative with ELISA-2, were retested by PCR and 3rd-generation antibody tests. One implicated donation was PCR positive, but anti-HCV negative. Both other donations were negative in all tests. The donor was recalled to the Blood Bank 13 weeks after the implicated donation and was found to be ELISA-3 plus RIBA-3 positive. Eight months after the implicated donation, the donor is still PCR and RIBA-3 positive, whereas the recipient became PCR negative but remained anti-HCV RIBA-3 positive. The case shows that blood products from donors collected during the open window period of an HCV infection can transmit HCV to recipients.     

Efficacy of a hepatitis C virus core antigen enzyme-linked immunosorbent assay for the identification of 'window-phase' blood donations

BACKGROUND AND OBJECTIVES: Recent studies have suggested that potentially infectious donations provided during the antibody-negative 'window' phase of hepatitis C virus (HCV) infection may be identified by testing for viral RNA or HCV core protein. We therefore evaluated the performance of an HCV antigen enzyme-linked immunosorbent assay (ELISA) for identification of window-phase donations and for prospective screening of blood donors. MATERIALS AND METHODS: One-hundred and twenty-eight archived plasma donations containing HCV RNA, but lacking antibody to HCV (anti-HCV), were tested by using the HCV antigen ELISA, together with 9951 freshly collected serum and plasma specimens from blood donors. RESULTS: HCV core antigen was detected in 94% (120/128) of window-phase plasma donations. Overall specificity in freshly collected blood donor specimens was 99.74%. Two putative window-phase donations containing HCV core protein and viral RNA were identified from paid plasma donors by prospective testing with the HCV antigen ELISA. CONCLUSION: These results indicate that an HCV antigen ELISA can identify almost all (94%) of viraemic donations given during the seronegative window phase of infection. The performance of the HCV antigen ELISA appears to be suitable for large-scale screening of blood donations.     

Low prevalence of HCV,HIV, and HTLV-I/II infection markers in northwestern Greece: results of a 3-year prospective donor study (1995-1997)

Background: The risk of infection with transfusion-transmitted viruses has been reduced remarkably. A zero-risk blood supply, however, remains a popular goal. A 3-year prospective donor study was conducted in the Epirus region of Greece to determine the prevalence of human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV), hepatitis B virus, and hepatitis C virus (HCV). Herein, we report the prevalence of HIV, HTLV, and HCV infection markers in this area. Methodology: Between January 1, 1995 and December 31, 1997, 6696 donors were investigated for the presence of anti-HIV, anti-HTLV, and anti-HCV antibodies using standard enzyme immunoassays (EIA). Every sample with anti-HCV reactivity by third-generation EIA was further investigated using a third-generation recombinant immunoblot assay (RIBA 3.0) and HCV-RNA by a combination of polymerase chain reaction (PCR) and DNA EIA. Results: None of the donors tested positive for anti-HIV or anti-HTLV antibodies. In contrast, anti-HCV was detected in 41 donors (0.61%). Using a RIBA 3.0 test, eight donors tested positive and eight had indeterminate results, while 25 tested negative. Seven of the eight donors with both EIA and RIBA 3.0 reactivity had increased levels of aminotransferases and detectable serum HCV-RNA. The remaining 34 donors had repeatedly normal aminotransferases and three times negative HCV-RNA. Liver biopsy was performed in anti-HCV/HCV-RNA-positive donors (7/41). The lesions were compatible with chronic hepatitis C in all of them. Conclusion: A zero prevalence of HIV and HTLV infection markers was found. Although the number of annual donations in this study was relatively low, the negative data for HIV and HTLV clearly indicate that rates of these infections are low in our region and that infected donors will be seen infrequently. HCV infection in blood donors remains very low in our region and is similar to the data reported in other industrialized countries. In fact, the prevalence of definite HCV infection seems to be very low (7/6696; 0.1%). However, a significant proportion of anti-HCV-reactive donors by third-generation EIA (33/41) had indeterminate or negative results by the RIBA 3.0. The latter donors were repeatedly negative for HCV-RNA. This finding may indicate that some donors tested false-positive for anti-HCV, although the possibility of true HCV infection contracted in the distant past cannot be excluded. In our opinion, close attention to mandatory principles of transfusion medicine, along with the screening of plasma donors using nucleic acid amplification technology, are the only methods that can further ensure the safety of our blood supply.     

Prevalence of hepatitis C infection and risk factors in hospitalized diabetic patients: results of a cross-sectional study

OBJECTIVES: Although there may exist a nosocomial risk of hepatitis C virus (HCV) infection in patients with type 1 or type 2 diabetes, this risk has not been fully investigated thus far and its magnitude is unknown. The aim of this multicenter cross-sectional study was to evaluate the prevalence of, and risk factors for, hepatitis C infection in consecutive hospitalized patients with diabetes and to assess the nosocomial risk and magnitude of HCV infection in these patients. PATIENTS AND METHODS: Consecutive hospitalized patients with diabetes seen in 11 French hepatogastroenterology and diabetology departments were studied. The prevalence of anti-HCV antibodies was compared with that observed in healthy blood donors and individuals seen during routine medical checkup. Diabetic patients with anti-HCV antibodies were compared with patients without anti-HCV antibodies for assessment of risk factors. RESULTS: In total 1561 patients were studied. Independent risk factors for HCV infection were assessed through multivariate analysis. Thirty-three patients (2.11%) had anti-HCV antibodies and 21 (63.70%) had HCV identified risk factors. The prevalence of HCV infection was higher in patients with diabetes than in blood donors (0.08%) or healthy controls (0.20%) (P<0.001). Multivariate analysis identified four independent risk factors for HCV infection: blood transfusion before 1991 [odds ratio (OR)=2.88, P=0.033], intravenous drug use (OR=21.37, P=0.012), treatment in a hepatogastroenterology center (OR=4.17, P=0.002) and a high number (>2) of previous admissions since the onset of diabetes (OR=2.52, P=0.039). CONCLUSION: A nosocomial source of HCV infection in hospitalized diabetic patients is suggested by the increased risk of HCV infection associated with the number of hospitalizations. This may account for at least 36% of cases of HCV infection.     

Prevalence and screening costs of hepatitis C virus among Ugandan blood donors

BACKGROUND: Screening donated blood for hepatitis C virus (HCV) is important for HCV prevention and is routinely practiced in North America and Europe. However, in many African countries little is known about HCV prevalence or cost-effectiveness of HCV antibody (anti-HCV) screening. METHODS: We investigated 2592 plasma specimens collected consecutively from blood donors in central Uganda in 1999. Routine screening by the blood bank included human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), and syphilis. To assess HCV prevalence and cost-effectiveness of testing, specimens were additionally tested for anti-HCV IgG by enzyme immunosorbent assay (EIA). Specimens repeatedly reactive (RR) on EIA were tested with a recombinant immunoblot assay (RIBA). RESULTS: Overall, 107 (4.1%) specimens were HCV EIA RR. Fifteen EIA RR specimens (0.6%, 95% confidence interval = 0.3-0.9%) were RIBA positive and 47 (1.8%) were RIBA indeterminate. Most (80%) RIBA-positive specimens were non-reactive for HIV, HBsAg, and syphilis. RIBA positivity was not associated with donor age, sex, number of donations, HIV, or HBsAg positivity. Costs of screening donors for anti-HCV by using EIA were estimated at US Dollars 782 per potential transfusion-associated HCV infection (exposure to RIBA-positive blood) averted. CONCLUSIONS: Current screening tests for other infections are ineffective in removing HCV-positive donations. Testing costs are considerable; cost-effectiveness of identifying HCV-infected donors will be critical in decision making about HCV screening in Uganda.     

HBV,HCV and HIV seroprevalence among blood donors in Istanbul,Turkey: how effective are the changes in the national blood transfusion policies?

The national blood transfusion policies have been changed significantly in recent years in Turkey. The purpose of this study was to determine the prevalence of HBV, HCV, and HIV in blood donors at the Red Crescent Center in Istanbul and to evaluate the effect of changes in the national blood transfusion policies on the prevalence of these infections. The screening results of 72695 blood donations at the Red Crescent Center in Istanbul between January and December 2007 were evaluated retrospectively. HBsAg, anti-HCV, and anti-HIV-1/2 were screened by microparticle enzyme immunoassay (MEIA) method. Samples found to be positive for anti-HIV 1/2 and anti-HCV were confirmed by Inno-Lia HCV Ab III and Inno-Lia HIV I/II Score, respectively. The seropositivity rates for HBsAg, anti-HCV, and anti-HIV-1/2 were determined as 1.76%, 0.07%, and 0.008%, respectively. Compared to the previously published data from Red Crescent Centers in Turkey, it was found that HBV and HCV seroprevalances decreased and HIV seroprevalance increased in recent years. In conclusion, we believe that the drop in HBV and HCV prevalence rates are likely multifactorial and may have resulted from more diligent donor questioning upon screening, a higher level of public awareness on viral hepatitis as well as the expansion of HBV vaccination coverage in Turkey. Another factor to contribute to the decreased prevalence of HCV stems from the use of more sensitive confirmation testing on all reactive results, thereby eliminating a fair amount of false positive cases. Despite similar transmission routes, the increase in HIV prevalence in contrast to HBV and HCV may be linked to the increase in AIDS cases in Turkey in recent years.     

Current incidence and residual risk of HIV, HBV and HCV at Canadian Blood Services

Estimates of the viral residual risk should be updated to reflect current incidence of infection in blood donors. Incidence rates were estimated for allogeneic whole‐blood donations made to Canadian Blood Services from 2006 to 2009 based on transmissible disease conversions of repeat donations within a 3‐year period. Residual risk was estimated as the incidence multiplied by the window period. The residual risk of HIV was 1 per 8 million donations, HCV 1 per 6·7 million donations and HBV 1 per 1·7 million donations. The residual risk remains low and has decreased for HCV since our previous estimates due to reduced incidence.     

Impact of nucleic acid amplification technology (NAT) in Italy in the three years following implementation (2001-2003)

The use of NAT technology to screen blood donations in Italy became mandatory on 28 June 2002, but had been available experimentally since 2001. During the transition period, an EIA test to detect hepatitis C core antigen (HCVcoreAg) had also been permitted. Considering the large number of blood transfusion centres in Italy, an initial reorganisation of the biological validation of blood units was necessary, with a partial centralisation of NAT testing. The Gruppo Italiano per lo Studio delle Malattie Trasmissibili con la Trasfusione (Italian Group for the Study of Transfusion-Transmissible Diseases) conducted a national survey evaluating NAT testing, based on an annual collection of data through a questionnaire sent to all centres. In the first three years of the investigation, 219 blood transfusion centres returned the questionnaires. In the period between January 2001 and December 2003, 3,894,894 blood donations were investigated for HCV RNA and 2,186,468 for HIV RNA. Of these, 12 were found to be HCV RNA positive and four HIV RNA positive, with an observed NAT versus antibody-based assay yield of 3.1/106 donations for HCV and 1.8/106 donations for HIV, respectively. Five of the 12 HCV RNA positive and anti-HCV negative donors had abnormal ALT values and their donations would have been discarded even in absence of NAT testing. Thus the final NAT yield for HCV is 1.79/106. The residual risk for HCV or HIV transmission by blood transfusion after NAT implementation is currently estimated to be extremely low in Italy.     

Hepatitis C virus and blood transfusion: past and present risks

The risk of HCV transmission by blood and blood products has been greatly reduced since the early 1980's. Selection of non-remunerated donors, donor selection to prevent HIV transmission, initial surrogate testing in some regions, and introduction of anti-HCV testing have all contributed to this. ALT surrogate testing has become obsolete since the introduction of anti-HCV testing. The residual risk of HCV transmission due to donations in the anti-HCV window period at present is about 1 in 100 000 transfusions of cellular products, and transmission of HCV by plasma products treated with modern inactivation methods such as solvent-detergent treatment, has not been reported. Hemovigilance programmes, which are presently being installed, will provide more data on the safety of blood transfusion. Introduction of HCV nucleic amplification technology (NAT) as a quality control of manufacturing pools for plasma products or as a form of blood donor screening by minipools is anticipated in many European countries for the coming year. Given industrial developments, NAT testing of individual blood donations may become available within the next 2 years. HCV NAT testing will further annihilate the residual risk, and the cost-effectiveness will become relatively low in comparison with other public health measures.     

Prevalence of Anti-Hepatitis C Virus in the Blood Donor Population of Rio de Janeiro

The prevalence of hepatitis C virus (HCV) antibodies in 2,557 asymptomatic volunteer Brazilian blood donors is reported. Using the line immunoassay (Inno-LIA) as a confirmatory test on ELISA anti-HCV-positive reacting sera, a prevalence rate of 2.7% for anti-HCV positivity was found. By comparison, prevalences of 1.6% for hepatitis B surface antigen, 0.9% for Treponema pallidum , 0.4% for human immunodeficiency virus and 0,04% for Trypanosoma cruzi were observed. Only 57% of the HCV-positive donors had elevated alanine aminotransferase (ALT) levels. Using previous criteria, based on surrogate markers (ALT ≥ 50 IU/1 and for anti-hepatitis B core antibody), for HCV infection at that time, only 25% of the HCV-positive donations would have been eliminated. In view of the high prevalence of anti-HCV reactivity among the Brazilian blood donor population and the poor reliability of surrogate markers, it is recommended that routine screening for anti-HCV in Brazilian blood donors is introduced.