Hepatitis C virus infection among First Nation and non-First Nation people in Manitoba, Canada — a public health laboratory study

Abstract

Demographic information and laboratory test results on 136 169 clinical serum specimens submitted to the public health laboratory in Manitoba, Canada, for hepatitis C virus (HCV) testing between January 1995 and December 2003 were analyzed. The difference in the clearance rates of HCV infection, without therapeutic intervention, and the HCV genotypes infecting First Nation and non-First Nation people were studied. The rates of co-infection of HCV-positive individuals with other hepatitis viruses were also compared between the two study groups. The results of the analyses of the data indicated that there was a 4.4-fold increase in the number of specimens tested and a 4.9-fold decrease in HCV antibody (anti-HCV) positive cases during the study period. The proportion of specimens submitted for testing from First Nation individuals was lower than their proportion in the Manitoba population. Our study also indicated that there was a significantly higher proportion of First Nation patients who had self-limiting infection (patients cleared the infection and became HCV RNA negative without anti-HCV treatment) in comparison to non-First Nation patients. The proportion of First Nation females who had self-limiting infection was significantly higher than non-First Nation females. HCV genotype 1 infection represented more than 60% of HCV infection in Manitoba. The rate of individuals positive for the hepatitis A virus antibody in the HCV-positive population was higher among First Nation than non-First Nation individuals. On the other hand, there were more HCV-infected First Nation patients than non-First Nation patients who were not immune to the hepatitis B virus. The data indicate that fewer First Nation patients seek anti-HCV therapy in comparison to non-First Nation. In conclusion, the differences in the rates of HCV self-limiting infection between First Nation and non-First Nation individuals in Manitoba may reflect the genetic differences between the two cohorts, which may consequently affect the immune response to the HCV infection.Key words: hepatitis A virus, hepatitis B virus, genotyping, mixed infection, self-limiting infection.