A population-based study of the epidemiology of hepatitis C in a North American population

Background & aims: Chronic hepatitis C virus (HCV) infection is a major public health problem with approximately 3% of the world's population thought to be chronically infected. However, population-based data regarding HCV incidence rates, prevalence, residence, age, and gender distributions within North America are limited. We aimed at providing a detailed descriptive epidemiology of HCV infection in a North American population with a focus on time trends in incidence rates and prevalence of newly diagnosed HCV infection since 1991, the time when laboratory testing for HCV infections became first available.

Methods: A Research Database was developed linking records from multiple administrative sources. HCV positive residents of the Canadian province of Manitoba were identified during a twelve-year period (1991-2002). The cumulative and annual incidence rates and the prevalence of newly diagnosed HCV infection in Manitoba were examined and compared between different demographic groups and urban vs. rural residents.

Results: A total of 5018 HCV positive cases were identified over a 12-year period. The annual number of newly diagnosed HCV infections peaked in 1998 (59.2/100,000). On the other hand, the known prevalence of HCV continued to increase (4.6-fold during the 12-year study period) among both men and women reflecting the chronic nature of the disease. Males were 1.7 times more often infected than females. HCV infections were more common in urban centers.

Conclusions: Between 1995 and 2002, there was a fairly constant trend for newly diagnosed HCV infection, ranging from approximately 500 to 600 new cases annually. Hence, with a stable population size, and a low case fatality rate, the prevalence of HCV infected persons in our population has been steadily rising. There is no evidence to suggest that the incidence of HCV infection will raise, however, the burden of chronic HCV infection will continue to increase, particularly amongst older males and those residing in urban centers.