Prevalence of anti-HCV and HCV viremia in hemodialysis patients in Taiwan.

Hepatitis C viral infection in 125 hemodialysis patients from Taiwan was studied using a second-generation anti-HCV immunoassay (EIA II) (Abbott HCV 2.0 EIA) and the polymerase chain reaction (PCR) to detect the HCV RNA in the serum. A total of 59 patients (47.2%) were positive by EIA II. In comparison, the conventional C100-3 anti-HCV assay was positive in 40 (32.0%). HCV RNA was found in 47 patients (37.6%). Patients with elevated serum transaminase level had a higher positive rate of anti-HCV and HCV RNA. The dialysis time was longer for those patients positive for anti-HCV than for those who were negative. A total of 57 of the 59 EIA II-positive cases had a history of blood transfusion. The HBsAg status did not influence the anti-HCV positivity. Among the 59 EIA II-positive patients, 66.1% were also positive for HCV RNA, and of the 47 HCV RNA-positive cases 83.0% were positive for EIA II. It is concluded that the high prevalence of specific HCV infection and HCV viremia was present in these patients. Prevention of cross-contamination during dialysis and blood screening before transfusion are important for the control of HCV infection in these patients.     

The detection of hepatitis C virus in South Hungary.

BACKGROUND: More than 100 million people are infected with hepatitis C virus (HCV) worldwide. The prevalence of HCV infection varies from country to country and the natural history of hepatitis C infection is not well understood. OBJECTIVES: The prevalence of anti-HCV positive blood donors in South Hungary was determined. Potential risk factors of HCV transmission were investigated and compared to anti-HCV-negative blood donors. Furthermore, the rate of anti-HCV positivity in children who had received one or more blood transfusions prior to the implementation of anti-HCV blood donor screening was evaluated. STUDY DESIGN: A total of 45719 blood donors and 120 children were tested for the presence of anti-HCV antibodies by second- and third-generation enzyme immunoassays. Positive results were confirmed by a recombinant immunoblot assay. Data on potential sources of HCV transmission were obtained by interviews. RESULTS: Among blood donors, the rate of confirmed HCV antibody-positives was 0.4% (195 of 45719 donors). Previous surgery, transfusion, more than three pregnancies, and tattoos were significantly correlated with confirmed anti-HCV positivity. Two of 120 children (1.7%) were confirmed anti-HCV positives. In both of them, serum HCV RNA could be detected. CONCLUSIONS: The prevalence of anti-HCV positive blood donors in South Hungary is low. Nosocomial infections and tattooing were found to be the most important risk factors for transmission of HCV. Because of the low prevalence of anti-HCV positive blood donors, only a small number of children, who received blood transfusions prior to the implementation of anti-HCV blood donor screening, are infected with HCV.     

15688名献血员抗-HIV、抗-HCV、HBsAg、梅毒检测结果研究

目的了解我市HIV、HCV、HBsAg、梅毒在一般献血人群的感染情况，确保输血安全。方法采用酶联免疫吸附试验检测抗-HIV、抗-HCV、HBsAg、RPR和TRUST试验检测梅毒。结果在献血人群中HBsAg阳性率为5．36％；抗-HCV阳性率为1．35％；梅毒阳性率为0．42％。结论多次献血者HBsAg检测阳性率较低；有献血浆史的献血者抗-HCV检测阳性显著高于一般人群。     

Epidemiology of hepatitis B and C in Croatia

The incidence of HBV and HCV infection is hard to determine because of the high number of asymptomatic infections. According to data of the Croatian Institute of Public Health, there are 200 newly infected persons with hepatitis B and approximately the same number of newly identified HBsAg carriers occur each year. Accordingly, Croatia is among the countries with less than 2% of HBsAg carriers in the general population. In these circumstances, HBV infection is most often spread among adolescents and younger adults. The route of transmission is most often sexual (semen) or through the skin in high-risk groups. An increased risk of infection is found in newborns of HBsAg positive mothers, i.v. addicts, promiscuous individuals, male homosexuals, person in close contact with acutely ill or chronic HBsAg carriers, persons that come in contact with blood and other potentially contaminated body fluids, dialysis patients, patients with multiple blood transfusions, patients with transplanted organ or tissue, patients treated for hematologic malignancies and hemophilia, and persons who undergo acupuncture, tattooing or piercing, or travel to areas with a high prevalence of HBV infection. The estimated prevalence of HCV infection marker (anti-HCV) in the Croatian general population is more than 1% and the number of yearly infected with hepatitis C reported to the Croatian Institute of Public Health is around 200 cases. The highest incidence is found in the 20-40 age groups at a high risk of infection by the use of drug injection. At risk are persons who received transfusion of blood or blood products prior to the availability of blood screening of voluntary blood donors.     

GB virus-C/hepatitis G virus infection in prostitutes: Possible role of sexual transmission

The modes of transmission of GB virus-C/hepatitis G virus (GBV-C/HGV) other than by blood transfusion are largely unknown. The prevalence of GBV-C/HGV viremia and the associated risk factors in 145 female prostitutes were examined. The seroprevalence of hepatitis B surface antigen (HBsAg), antibodies to hepatitis C virus (anti-HCV), and GBV-C/HGV RNA were 14%, 18%, and 11%, respectively. The demographic characteristics were similar between subjects with and without HBsAg. In contrast, those with HCV or GBV-C/HGV infection had practised longer as prostitutes and received blood transfusion more frequently. Moreover, the prevalence of GBV-C/HGV RNA and anti-HCV tended to increase in parallel with the duration of prostitution. These results suggest that like HCV, sexual transmission of GBV-C/HGV occurs and the risk increased with prolonged duration of exposure. The transmission efficiency between GBV-C/HGV and HCV appears to be similar. J. Med. Virol. 52:381–384, 1997 , © 1997 Wiley-Liss, Inc.     

Familial clustering of hepatitis B and C viruses in Korea.

In order to evaluate the familial clustering of hepatitis B virus(HBV) and hepatitis C virus(HCV) infections and to elucidate the possible routes of HCV transmission among Korean adults with chronic liver disease, 137 household contacts of 51 chronic carriers of HBsAg and 111 household contacts of 38 controls, and 181 household contacts of 96 anti-HCV positives and 102 household contacts of 76 anti-HCV negatives were tested from July 1990 to March 1994. Of 71 non-vaccinated household contacts of HBsAg carriers, 10 gave positive result for HBsAg(14.1%), but none of the household contacts of the controls were positive for HBsAg(p < 0.05). Familial clustering of HBV infection was found, when the offspring of carriers and controls were compared. A significantly higher percentage of the offspring of carriers were positive for HBV infection(54.6% vs 15.4%, p < 0.05) with OR of 6.6(95% Cl; 1.3-34.5). No evidence of familial clustering of HCV infection was found with 2.2%(4/181) anti-HCV positivity among the household contacts of index cases, similar to 1.0%(1/102) among those of controls. History of acute hepatitis(OR 3.2), transfusion(OR 3.2), and acupuncture(OR 2.5) were associated with an increased risk of HCV infection. In conclusion, HBV has strong familial clustering whereas HCV does not in Korea.     

Prevalence of hepatitis C virus antibody among Korean adults.

To estimate the prevalence of hepatitis C virus (HCV) infection among Korean adults and to present the putative route of HCV transmission among them, serum samples from 4917 adults older than 20 years of age were tested for antibody to HCV (anti-HCV), and histories of blood transfusion and other pertinent information were obtained by self-administered questionnaires. The overall prevalence of anti-HCV was 1.7%; prevalence was 1.4% in subjects with normal levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), 3.3% in those with slightly elevated and 5.9% in those with markedly elevated levels of the enzymes. The prevalence of anti-HCV increased with increasing age (P < 0.01), but was not associated with blood transfusion. The present study suggests that the prevalence of HCV infection was 1.4% and that the major routes of HCV transmission may be other than blood transfusion in healthy Korean adults.     

2450例患者输血前感染性指标检测结果分析

目的 检测与分析患者输血前的感染性指标水平,为临床血液传染病的预防控制提供参考.方法 选取2013年6月至2016年1月期间我院收治的2450例拟接受输血的患者作为研究对象,采用酶联免疫吸附法(enzyme linked immunosorbent assay,ELISA)测定患者输血前的感染性指标检测,包括乙型肝炎五项标志物、抗丙型肝炎病毒抗体(hepatitis c virus antibody,抗-HCV)、抗人类免疫缺陷病毒抗体(human immunodeficiency virus antibody,抗-HIV)以及抗梅毒螺旋体抗体(treponema pallidum antibody,抗-TP),结果 2450例患者输血前感染性指标检测中,乙肝表面抗体(hepatitis B surface antibody,HBsAb)的阳性率最高,为23.18%,其次为乙型肝炎病毒表面抗原(hepatitis B surface antigen,HBsAg),阳性率为11.27%;患者存在2~3重感染模式,其中以乙型肝炎E抗体(hepatitis B e antibody,HBeAb)+HBsAb模式的阳性率最高,为1.18%,其次是HBsAg+HBsAb+乙肝表面核心抗体(hepatitis B core antibody,HBcAb)模式的,为1.06%;男性患者乙型肝炎e抗原(hepatitis B e antigen,HBeAg)、HBeAb、HBsAg、HBsAb、HBcAb、抗-HCV、抗-HIV和抗-TP阳性率均高于女性患者的,但差异无统计学意义;年龄>60岁患者的HBeAg、HBeAb、HBsAg、抗-HCV和抗-TP阳性率明显低于年龄<30岁和年龄为30~60岁患者(P<0.05).而各年龄段间的HBsAb、HBcAb和抗-HIV阳性率比较,差异无统计学意义(P>0.05).结论 输血患者输血前感染性指标的检测均具有一定比例的阳性检出率.加强输血前感染性指标的检测,可保证临床用血安全,减少医疗纠纷.     

Seroprevalence of HBsAg, anti-HCV, and anti-HIV among haemophiliac patients in Shiraz, Iran

A study was performed during 1999-2000 on multi-transfused patients with haemophilia who are registered by the Shiraz Haemophilia Society. HBsAg, anti-HCV, and anti-HIV were checked using a second-generation enzyme-linked immunosorbent assay (ELISA). Positive tests for anti-HCV and anti-HIV were confirmed by a western blot test. Healthy blood donors were used for the control group. HBsAg, anti-HCV, and anti-HIV were positive in two (0.71%, 95% CI = 0.12-2.33), 44 (15.65%, 95% CI = 11.76-20.26), and one (0.36%, 95% CI = 0.02-1.74) of the patients, respectively. Positive sera for HBsAg, anti-HCV, and anti-HIV were found in 85 (1.07%), 47 (0.59%), and 27 (0.34%) of the control group, respectively. The rate of anti-HCV was significantly higher in the patients than in the control group (p < 0.0001). The rate of positive anti-HCV was significantly higher than that of positive HBsAg in the patients (p < 0.0001). The reverse was correct for the control group (p = 0.0008). It is concluded that HCV is the current major problem in multi-transfused haemophiliac patients and more careful pre-transfusion screening of blood for anti-HCV must be introduced in all blood banks.     

Hepatitis C virus in sickle cell disease

PURPOSE: To determine the prevalence of hepatitis C virus antibodies (anti-HCV) in patients with sickle cell disease. PATIENTS AND METHODS: Between 1983 and 2001, 150 patients from the Howard University Hospital Center for Sickle Cell Disease were screened for HCV antibody (52% women, 48% men, mean age 34 years). Frozen serum samples from 56 adult sickle cell patients who had participated in previous surveys (1983-92) of HIV and HTLV-1 serology and who were tested in 1992 for anti-HCV antibody--when commercial ELISA test (Ortho) became available--were included in this paper. Of the 150 patients in the study, 132 had sickle cell anemia genotype (SS), 15 had sickle cell hemoglobin-C disease (SC) and three had sickle beta thalassemia. Clinical charts were reviewed for history of blood transfusion, IV drug abuse, homosexuality, tattooing, iron overload, and alcohol abuse. RESULTS: Antibodies to HCV were detected in 53 patients (35.3%). Of the 55 patients who had frozen serum samples tested in 1992, 32 (58%) were reactive for anti-HCV, while only 21 of the 95 patients (22%) tested after 1992 were positive for HCV antibodies (P<0.001). Thirty-nine of 77 patients (51%) who received more than 10 units of packed red blood cells were positive for HCV antibody, and only 14 of 61 patients (23%) who received less than 10 units of packed red blood cells transfusion were positive for HCV antibodies (P<0.001). None of the 12 patients who never received transfusion were positive for HCV antibody. In the 53 anti-HCV positive patients, the mean alanine amino-transferase (ALT) value was 98- and 81 U/L, respectively, for males and females. These values were normal for the HCV-antibody negative patients. The aspartate amino-transferase (AST) and the total bilirubin were also higher in the anti-HCV positive patients compared to patients in the anti-HCV negative group. Forty-four patients (57.1%) who were transfused more than 10 units developed iron overload defined by a serum ferritin level higher than 1,000 ng/ml. A total of 20 of the patients with iron overload underwent liver biopsies. Seven of these 20 patients (35%) were HCV positive. These patients often had more severe liver disease and higher degree of iron deposition. CONCLUSION: The prevalence of HCV antibody and iron overload is directly related to the number of blood transfusions in patients with sickle cell disease. The prevalence of HCV infection has decreased significantly, since blood donor screening for HCV became available. Chronic HCV infection and iron overload place sickle cell patients at risk for significant liver disease.     

Prevalence of viral hepatitis markers in Korean patients with hepatocellular carcinoma.

The positive rates of hepatitis B surface antigen (HBsAg) and antibody to hepatitis C virus (anti-HCV) were analyzed according to year, sex, age, and serum ALT levels in 1,370 patients with hepatocellular carcinoma (HCC) who visited the Korea Cancer Center Hospital between January 1989 and December 1994. The positive rate of HBsAg was 68.8 to 76.0% per year in patients with HCC, while that of anti-HCV was 3.2 to 9.8% per year. No sex predominance was found in the positive rates of HBsAg and anti-HCV. HBsAg positivity was distributed mostly in the 41 to 50 age group, whereas anti-HCV positivity was distributed mostly in the over 50 age group. Higher positive rate of anti-HCV was observed in HCC patients with serum ALT levels above the normal range than in those with serum ALT levels within the normal range. However, elevated serum ALT levels above the normal range was not related to the positive rate of HBsAg. The relatively low prevalence of anti-HCV in patients with HCC suggests that the role of HCV infection in the development of HCC lower than that of HBV infection in Korea. However, our results suggest that HCV is another potent risk factor for HCC even in HBV endemic areas.     

Evaluation of antibodies to hepatitis C virus in a study of transfusion-associated hepatitis

BACKGROUND. The hepatitis C virus (HCV) is now known to be the chief cause of transfusion-associated non-A, non-B hepatitis, but the prevalence of HCV among blood donors and the frequency of transmission by blood transfusion are unknown. METHODS. To assess the sensitivity and specificity of a test for antibody to HCV, we tested serum samples from participants in a large study of transfusion-associated hepatitis. Samples were obtained prospectively from consecutive adults undergoing open-heart surgery in Spain, but were tested retrospectively, after the antibody enzyme immunoassay for anti-HCV became available. RESULTS. Of 280 transfusion recipients given a total of 1109 units of blood, 27 (9.6 percent) had transfusion-associated non-A, non-B hepatitis (mean follow-up, 52 weeks) and 24 of the 27 seroconverted to anti-HCV-positive, whereas only 2 (0.8 percent) of the remaining transfusion recipients seroconverted. Among the 1044 donor specimens available for testing, 16 (1.5 percent) had anti-HCV antibody. Only 1 additional seropositive donor was found when 44 implicated donors who had been seronegative were retested 9 to 12 months later. Of the 16 recipients of anti-HCV-positive blood, 14 (88 percent) had transfusion-associated hepatitis and seroconverted to anti-HCV-positive. The remaining two recipients had neither hepatitis nor anti-HCV antibody. Among 25 patients with non-A, non-B hepatitis for whom all transfused blood was tested, 14 had received blood positive for anti-HCV. CONCLUSIONS. About 90 percent of blood donors with antibody to HCV have infectious virus in their blood. The screening of blood donors for anti-HCV antibody should prevent about half the cases of transfusion-associated hepatitis, but the donors with infectious virus who are anti-HCV-negative may remain seronegative for prolonged periods.     

Importance of sexual transmission of hepatitis C virus in seropositive pregnant women: A case-control study

The mode of hepatitis C virus (HCV) transmission in patients who deny parenteral exposure is still not understood. Seroprevalence studies of anti-HCV in sexually promiscuous populations and in spouses of infected patients have given contradictory results. We investigated the role of sexual transmission of HCV in a case-control study of risk factors for infection in a series of 43 anti-HCV positive pregnant women and 172 matched controls (4 for each case). In the univariate analysis, the following factors were associated significantly with anti-HCV seropositivity: low social class, unmarried, history of abortion, wounds which were sutured, tattooes, sharing toiletries with the partner, sexual contact outside the partnership without condom use, blood transfusion, and intravenous drug abuse, but only the last 3 factors remained significantly associated with HCV infection in multiple logistic regression analysis. The relative risk of HCV infection increased according to the increased number of sexual partners. Thus sexual transmission must be considered a possible mode of infection in HCV infected persons without parenteral exposures. J. Med. Virol. 52:164–167, 1997. © 1997 Wiley-Liss, Inc.     

Analysis of integrated hepatitis B virus DNA and flanking cellular sequences in a childhood hepatocellular carcinoma

Hepatitis C virus (HCV) is transmitted mainly by the parenteral route after percutaneous exposure to virus-infected products or body fluids. Thus, HCV shares with hepatitis B and D (HBV, HDV) viruses this common transmission route. The prevalence of antibody against HCV (anti-HCV) was studied in 1155 serum samples from individuals at risk of infection by bloodborne or sexually transmitted agents, as well as from others lacking such risk factors, from the city of Maracaibo, Venezuela. Anti-HCV and serological markers of infection by HBV and HDV were also studied in further 550 samples taken from Bari Indians living in different communities in the Perija mountains. State of Zulia, Venezuela. The results obtained showed that recipients of blood or blood products are at increased risk of HCV infection in Maracaibo, whereas sexual transmission plays only a minor role if any. Both HBV and HDV infections were highly prevalent among Bari Indians (64.4% positive for anti-HBc; 11.1% of HBsAg carriers; 15.3% positive for anti-HDV among HBsAg carriers). No anti-HCV positive samples were, however, detected among them, thus suggesting either that HCV has not still reached this population or that HBV and HDV are transmitted by routes unshared by HCV. Anti-HCV was also absent among samples from mentally retarded patients from Maracaibo, thus confirming similar findings from other countries and supporting the existence of specific transmission mechanisms for HBV and HDV which are not working for HCV. © 1994 Wiley-Liss, Inc.     

Endemic hepatitis C virus infection in a Sicilian town: further evidence for iatrogenic transmission

The prevalence of and risk factors for HCV and HBV infections in the general population and the predictive value of ALT screening in identifying anti-HCV positive subjects have been evaluated in a small Sicilian town. A random 1:4 sampling from the census of the general population was performed. Anti-HCV, HCV-RNA, HCV genotype, HBsAg, and anti-HBc were tested. The linkage between HCV infection and potential risk factors was evaluated by multiple logistic regression analysis. Among 721 subjects studied, 75 (10.4%) were anti-HCV positive. The HCV infection rate increased from 0.4% in subjects 10-29 years of age to 34% in those > 60 years of age. Among the 75 anti-HCV positive subjects, 66.7% were HCV-RNA positive and 36% had abnormal ALT, in contrast abnormal ALT levels were found in 4.3% of the 646 anti-HCV negative subjects (P < 0.01). HCV genotype 1b infected the majority (88.0%) of viremic subjects. Exposure to HBV infection (anti-HBc positivity) was found in 11.2% of subjects; HBsAg positivity was 0.7%. At multivariate analysis, two variables were associated with HCV infection: age > or = 45 years (OR 27.8; CI 95% = 11.0-70.2) and previous hospitalization (OR 2.5; CI 95% = 1.3-4.7). ALT testing had low positive predictive value (PPV = 49.1%) for HCV infection. The positive predictive value was good (88%) in people > or = 60 years of age, but minimal (16.7%) in those below 60. These findings indicate that HCV infection is common in the elderly, perhaps as a result of past iatrogenic transmission. The present low rate of HCV infection among the younger generations coupled with the low progression of the viral related liver damage does not support the projection of a future increasing incidence in the next decades of the burden of HCV-related chronic disease. HBV infection, formerly common in this area, is already in sharp decline. In an area of high HCV endemicity, screening of the general population by ALT cannot be used a surrogate marker to detect HCV infection in those susceptible to treatment.     

Tattooing as a risk of hepatitis C virus infection.

The association of hepatitis C virus (HCV) infection and tattooing was studied in 87 tattooed and 126 tattoo free healthy young men who did not engage in intravenous drug use or multiple sexual activity. Antibody against HCV (anti-HCV) was tested in serum specimens by enzyme immunoassay with C100-3, NS3, and core antigens; 11 of the 87 (12.6%) tattooed and 3 of the 126 (2.4%) tattoo free subjects were positive for anti-HCV (odds ratio = 5.9, 95% CI = 1.6-22.0). A relationship was demonstrated by an increased risk for HCV infection with an increasing number of tattooed site (P(trend) = 0.002). All but one of the 87 tattooed subjects had been infected by hepatitis B virus (HBV) and 25 were carriers of hepatitis B surface antigen (HBsAg). None of the 25 HBsAg carriers was positive for anti-HCV whereas 11 of the 62 HBsAg non-carriers had anti-HCV, suggesting a negative association between the HBsAg carriage and the long lasting anti-HCV (P = 0.02, Fisher's exact). The status of the tattooer was also an important determinant for HCV infection; the risk was higher if tattooing was done by a non-professional friend than by a professional tattooist. Tattooing, probably with improperly sterilized needles, can clearly pose an increased risk for HCV infection in Taiwan. This study indicates the need for legal standards for hygienic tattooing as part of preventive measures for the control of parenterally transmitted infections.     

粤东地区不同人群丙型肝炎病毒感染情况分析

目的 :了解粤东地区不同人群丙型肝炎病毒 (HCV)感染情况 ,探讨HCV感染途径。方法 :运用酶联免疫吸附试验 (ELISA)及荧光定量聚合酶链式反应 (FQ -PCR)检测不同人群血清中抗 -HCV及HCV -RNA。结果 :抗 -HCV阳性率在一般人群中为 0 89% (5 8/ 6 4 6 8) ;医护人员 2 93% (5 / 171) ;乙型肝炎病人11 5 % (47/ 4 10 ) ;普通孕妇 0 93% (17/ 1836 ) ,其中 12例HCV -RNA阳性 ,所生 12名婴儿 2名阳性 ,母婴传播率 16 7% ;血液透析病人 5 1 4 % (5 4 / 10 5 ) ,其中有输血史的 5 8% (5 1/ 88) ,无输血史的 17 7% (3/ 17) ,两者有极显著性差异 (χ2 =7.72 ,P <0 .0 1)。结论 :血途径是HCV感染的主要传播途径。母婴传播及医务人员的被感染值得重视。     

Intrafamilial transmission of hepatitis C virus in hemodialysis patients

The prevalence of hepatitis C virus (HCV) infection in chronic hemodialysis patients ranges from 20 to 50% and these patients may serve as a reservoir of infection for their household contacts. The aim of this study was to investigate the prevalence of anti-HCV in hemodialysis patients and their families, and to evaluate possible routes of infection. One hundred eighty-six family members of 84 hemodialysis patients and 529 healthy adults were enrolled. The family members consisted of 50 spouses, 96 children, 11 parents, 29 siblings, and other relatives living together with the patients. Serum samples were collected for testing anti-HCV. Exposure to risk factors was obtained by a questionnaire and an interview. The results showed that prevalence of anti-HCV in hemodialysis patients was 44%, whereas in family members it was 5.4%, not significantly different from that of age-matched healthy adults (standardized morbidity rate = 1.51, P = 0.390). The anti-HCV rate in family members tended to increase with age, and a spouse of an infected hemodialysis patient had a higher risk of HCV infection than other family members (15% vs. 2.6%, odds ratio 6.6, P = 0.058). Except for the age factor, no difference was found between seropositive and se-ronegative family members with respect to risk factors such as blood transfusion, surgery, frequent injections, dental procedures, or acupuncture. It was concluded that, although the anti-HCV positivity of hemodialysis patients is high, the risk of HCV infection for their family members is not higher than that of the general population. Among family members, spouses of seropositive hemodialysis patients have the highest risk of HCV infection. These data imply that long-term intimate contact between spouses plays a key role in the intrafamilial transmission of HCV. © 1995 Wiley-Liss, inc.     

Hepatitis C virus infection in post-transfusion hepatitis. An analysis with first- and second-generation assays.

BACKGROUND. The causes of post-transfusion non-A, non-B hepatitis are still not fully defined, nor is it clear how accurate the tests are that are used to screen blood donors for hepatitis C virus (HCV) and to diagnose post-transfusion hepatitis caused by infected blood. METHODS. We used two first-generation enzyme-linked immunoassays (EIAs) and one second-generation immunoassay to test for anti-HCV antibodies in serum samples collected between 1976 and 1979 in the Transfusion-Transmitted Viruses Study (from 1247 patients who underwent transfusion and 1235 matched control subjects who did not receive transfusions). We tested serum collected before and after infection from the patients in whom non-A, non-B hepatitis developed, serum from their blood donors, and serum from 41 of the control subjects who had hepatitis unrelated to transfusion. RESULTS. Of the 115 patients in whom post-transfusion non-A, non-B hepatitis developed, the initial serum samples of 111 were anti-HCV-negative; after hepatitis developed in these 111 patients, the first-generation EIAs detected anti-HCV in 51 (46 percent), and the second-generation assay detected anti-HCV in an additional 16 (14 percent), for a total of 60 percent. Of 40 controls, 37 were anti-HCV-negative initially, and none seroconverted after hepatitis developed. If the 3 percent rate of non-A, non-B, non-C hepatitis among the controls (37 of 1235) was applied to the 1247 transfusion recipients, only 74 of the 111 cases of hepatitis were attributable to the transfusion. Thus, 91 percent (67 of 74) of the cases of post-transfusion hepatitis were caused by HCV. Of the 99 donors, 60 were HCV-positive (9 on second-generation tests only) and 39 were not. CONCLUSIONS. Nearly all cases of non-A, non-B post-transfusion hepatitis are caused by HCV. Screening with a second-generation assay improves the rate of detection of HCV infection in patients with post-transfusion hepatitis and in blood donors. The use of this test showed a 3.6 percent risk of non-A, non-B, non-C hepatitis, which was not significantly different from the rate in the controls (3.0 percent).