Hepatitis C transmission on the north coast of New South Wales: explaining the unexplained.

OBJECTIVE: To determine the routes of hepatitis C virus (HCV) transmission in an Australian community.

DESIGN: Questionnaire-based, cross-sectional survey of notified HCV cases.

SUBJECTS AND SETTING: All cases notified to the New South Wales North Coast Public Health Unit between 1 January 1993 and 30 September 1994.

OUTCOME MEASURES: Frequency of potential transmission exposures (parenteral and sexual); most likely primary exposure; HCV infection rates in sexual partners and offspring.

RESULTS: 467 subjects responded (47% of resident cases). Of these, all but one reported actual or potential blood exposures (injecting drug user [IDU], 85%; IDU with sharing of injection equipment, 76%; pre-1990 blood transfusions, 6%; other blood exposures, 8%). Most subjects reported multiple exposures and none reported sexual contact as the only potential exposure. Of 233 sexual partners tested for HCV, 83 were positive; 54 of these were questioned and all had other parenteral exposures. Only three children out of 91 children tested were positive for HCV (two expressing maternal antibodies).

CONCLUSIONS: In contrast with previous studies, possible HCV transmission modes were identified for almost all respondents. Most respondents in this community were IDUs. Non-parenteral transmission appeared minimal. Novel approaches to preventing HCV transmission in IDUs are needed.