Failure to detect hepatitis C virus genome in human secretions with the polymerase chain reaction

Although hepatitis C infection has been clearly demonstrated to be transmitted through blood products or blood contamination, most cases of sporadic hepatitis C infection are unassociated with parenteral risk factors, and it is unclear how infection might be acquired by nonparenteral means. One potential mode of nonparenteral transmission is through body secretions. We used a highly sensitive and specific polymerase chain reaction assay to determine whether hepatitis C viral genomic RNA could be detected in secretions obtained from nineteen individuals with chronic hepatitis C virus infection. Although hepatitis C genomic RNA was found in all 19 sera, hepatitis C virus RNA was not detected in any samples of saliva, semen, urine, stool or vaginal secretions from these patients. Viral titers in serum ranged from 10(2) to 10(7) polymerase chain reaction units/ml. The sensitivity of our polymerase chain reaction assay indicates that, if hepatitis C virus were in secretions, it would be present in amounts less than 1 to 4 polymerase chain reaction units/ml. This contrasts with hepatitis B virus infection, in which serum titers frequently are in excess of 10(9) copies of hepatitis B genomes/ml. Body secretions have been found to contain up to 10(6) copies of hepatitis B genomes/ml. Our findings support seroepidemiological studies indicating that nonparenteral transmission of hepatitis C through secretions is uncommon and probably much less efficient than hepatitis B virus infection.