Hepatitis A, B, and C in Canada. Results from the National Sentinel Health Unit Surveillance System, 1993-1995.

Objectives: To estimate the incidence of and to describe the risk factors that were associated with the acquisition of hepatitis A, B, and C in well-defined Canadian populations from the Sentinel Health Unit Surveillance System (SHUSS).

Methods: We used the 1993 to 1995 data on hepatitis A, B, and C infection in Canada, collected by SHUSS, a national surveillance system established by the Laboratory Centre for Disease Control in Health Canada in 1993, through consultation and collaboration with provincial partners. We calculated the rates of, and described and discussed the risk factors that were associated with, hepatitis A, B, and C infection, based on the SHUSS surveillance data.

Results: From 1993 to 1995, SHUSS reported 92 cases of hepatitis A, 89 hepatitis B, and 720 hepatitis C, yielding a rate of 3.9, 3.8, and 30.3 per 100,000, respectively. The reported rates varied substantially among participating health units, ranging from 0.8 to 8.1 per 100,000 for hepatitis A, 0.0 to 9.0 for hepatitis B, and 5.4 to 73.3 for hepatitis C. The most frequently reported risk factor for hepatitis A was a history of street drug use, followed by recent international travel and household contact with a hepatitis A case, household crowding, and a history of raw or undercooked shellfish consumption. The most frequently reported risk factors for the acquisition of hepatitis B included history of street drug use and occupational exposure. The most frequently reported risk factor for the acquisition of hepatitis C was a history of street drug use, followed by health care exposure and occupational exposure. Only 5% of persons with hepatitis B infection had a history of hepatitis B immunization.

Interpretation: Despite the limitations of possible bias due to selective participation of SHUSS and the lack of information on risk factors among controls, the high exposure to known risk factors and the low rate of vaccination among hepatitis patients can provide useful information for the development of public health policies to control hepatitis A, B, and C infection in Canada.