Investigating the source of hepatitis C virus infection among individuals whose route of infection is undefined: a study of ten cases.

Hepatitis C virus (HCV) transmission is predominantly parenteral via infected blood products or shared injecting equipment. Many infected individuals, however, deny these risk factors. This study set out to determine whether an in-depth interview would determine the likely source of infection for those whose route of infection was undefined. Between May 1999 and July 1999, risk factor information was sought, through in-depth interview, from 10 patients whose source of hepatitis C infection was undefined. The clinical notes of the patients were scrutinized to complement the information provided through the questionnaire. Despite undertaking an in-depth interview, it was not possible to establish the likely route of infection for 9 of the 10 individuals studied as they reported several risk events. There is little benefit to interviewing routinely those HCV-infected people who have no history of injecting drugs or having received a contaminated blood/blood product transfusion, to ascertain their likely source or time of infection; at best, such effort might only increase one's confidence that infection was acquired through means other than these 2 routes.