Characterization of Acute and Chronic Hepatitis B Virus Genotypes in Canada.

OBJECTIVE: The prevalence and distribution of hepatitis B virus (HBV) genotypes in Canada is not known. Genotypic analysis may contribute to a better understanding of HBV strain distribution and transmission risk. METHODS: HBV surface antigen (HBsAg) positive samples of acute (n = 152) and chronic (n = 1533) HBV submitted for strain analysis or reference genotype testing between 2006 and 2012 were analyzed. The HBsAg coding region was amplified to determine the HBV genotype by INNO-LiPA assay or sequence analysis. Single and multivariate analyses were used to describe genotypes' associations with known demographic and behavioral risk factors for 126 linked cases of acute HBV. RESULTS: Nine genotypes were detected (A to I), including mixed infections. Genotype C (HBV/C) dominated within chronic infections while HBV/D and A prevailed among acute HBV cases. History of incarceration and residing with a chronic HBV carrier or injection drug user were the most frequently reported risks for acute HBV infection. Over time, HBV/A increased among both acute and chronic infections, and HBV/C and HBV/D decreased among chronic infections. CONCLUSION: Chronic and acute HBV genotypes in Canada differ in the relative distribution and their associations with known risk factors, suggesting different routes of transmission and clinical progression of infection.

Identifying and describing a cohort effect in the national database of reported cases of hepatitis C virus infection in Canada (1991-2010): an age-period-cohort analysis.

BACKGROUND: Hepatitis C virus (HCV) infection has a high likelihood of becoming chronic and lead to a range of conditions with poor health outcomes. Identifying birth groups highly affected by HCV infection may better focus public health interventions and ensure their cost-effectiveness. Our analysis focused on studying the association of the birth year and reporting period with rates of cases of HCV infection reported in Canada over a 20-year period. METHODS: Laboratory-confirmed acute or chronic HCV cases with information on sex, age and year of report from 6 provinces and territories that reported line-listed data to the Canadian Notifiable Diseases Surveillance System from 1991 to 2010 were used. Sex-specific infection rates for 5-year birth groups born between 1921 and 1990 were calculated. Rates of HCV infection were log-logit transformed and underwent mean polish analysis and panel linear regression. Rate ratios of HCV infection in the 5-year age groups and their 95% confidence intervals were calculated, with rates in males and females born in 1941-1945 used as references. RESULTS: Males born between 1946 and 1970 had 21%-40% higher reported rates of HCV infection, whereas females born between 1946 and 1975 had 12%-43% higher reported rates compared with rates in the respective sexes who were born in 1941-1945. INTERPRETATION: Individuals born between 1946 and 1965 contributed the most to the rates of HCV infection reported in Canada between 1991 and 2010. The cohort effect was present in male and female cases of HCV infection with birth year up to 1970 and 1975, respectively. Our findings will support the development of HCV prevention programs and policies in Canada.