Hepatitis C virus antibodies among different groups at risk and patients with suspected non-A, non-B hepatitis.

4000 sera were tested for antibodies against hepatitis C virus (HCV) by means of an ELISA using the C100-3 antigen. 38.9% of patients with non-A, non-B hepatitis following blood transfusion (n = 108) had HCV antibodies. Among patients with chronic liver damage of unknown origin (n = 316) 30.4% were anti-HCV positive, and in 2,506 patients with transitional or chronic elevation of transaminases 14.8% showed HCV antibodies. Haemophiliacs (n = 26) with 65.4% anti-HCV positives and drug addicts (n = 46) with 56.5% anti-HCV positives had the highest prevalence among high risk groups. Addicts dying from drug abuse (n = 216) and HIV 1 positives (n = 127) were anti-HCV positive in 37.5% and 26.0%, respectively. Patients on haemodialysis (n = 331) had antibodies against HCV in 12.4%. Health care workers (n = 217) appear to be at a comparably low risk with only 2.8% anti-HCV positives. Up to now we could not find a single case of intrafamilial spread of HCV in 46 examined cases. We suggest that HCV infectivity of contaminated body fluids and blood is lower than that of hepatitis B virus or human immunodeficiency virus type 1 carriers. In suspected non-A, non-B hepatitis negative test results should be confirmed in a second sample because it may take three to six months after infection before HCV antibodies occur. However, about 10% of chronic HCV infections are not detectable with the presently available test. This may change when new tests become available using HCV specific antigens other than C100-3.