Human Immunodeficiency Virus (HIV) and Hepatitis C Virus (HCV) in a Northern Alberta Population
Bowker, Samantha L., Soskolne, Colin L., Houston, Stan C., Newman, Stephen C., Jhangri, Gian S., Canadian Journal of Public Health
Objective: To describe the demographics and estimate the prevalence of hepatitis C virus (HCV) in a cohort of Human Immunodeficiency Virus (HIV) positive patients in Northern Alberta.
Methods: A cross-sectional (prevalence) study was performed on a cohort of HIV-positive patients. HCV testing was not widely available until December 1989, and the more sensitive, second generation immunoassay was not available until 1992. To reduce the effect of testing bias, we restricted consideration of HCV status to patients first seen January 1, 1992 onward.
Results: Forty-four percent of patients in the whole cohort were tested for HCV (564/1,276) and 62% (505/809) of patients entered since January 1, 1992 were tested for HCV. During the period January 1, 1 992-December 31, 1 999, the prevalence of HCV in our cohort of northern Alberta HIV-positive patients was at least 37.9% (307/809) and was 60.8% (307/505) among those who were tested for HCV in 1 992 or later. The mean age of the coinfected group was 33.6 years, 66.1% were male, 91.2% were injection drug users (IDUs), 56.8% were Caucasian, and 40.0% were Aboriginal. A statistically significant difference was found between the HCV-negative cohort, the HCV co-infected cohort, and the HCVuntested cohort for the following variables: risk behaviour, gender, ethnic status, death, occurrence of an AIDS-defining illness (p<0.0001), and mean baseline CD4 cell count (p=0.002).
Conclusion: A high proportion of the HIV-infected IDUs was co-infected with HCV. Compared to the HCV-negative group, the co-infected group appears to have had less advanced HIV disease. This is likely a reflection of more recent HIV infection in the HCV co-infected group.
Since the early 1980s, when the Human Immunodeficiency Virus (HIV) pandemic began in Canada, there has been a steady decline in the proportion of incident HlV infections nationally among men who have sex with men (MSM), from over 80% during 19811983, to 29.5% in 1996, followed by an increase once again in 1999 to 38.4%. In contrast, there has been a substantial increase in the proportion of incident HIV infections among injection drug users (IDUs), from less than 10% before 1986, to 24% in 1987-1990, and to 46.9% in 1996.1 However, there has been a recent decline in the proportion of newly-infected IDUs to 34.1% in 1999. Thus, a large proportion of new HIV infections in Canada are occurring in IDUs, explaining the substantial and growing importance of HIV and hepatitis C virus (HCV) coinfection. In the Montreal drug user cohort study, the cumulative probability of HIV seroconversion was 33% for needle exchange program (NEP) users and 13% for non-users.2 Furthermore, as treatment for HIV improves, liver disease accounts for an increasing proportion of morbidity and mortality in the HIV-infected.
HCV was first cloned in December 1989, and is the cause of more than 90% of parenterally-acquired non-A, non-B hepatitis.3 Prior to 1990, there was no test commercially available to detect HCV
antibody in the population. Although a very small percentage of patients with histories of sexual exposure (1-10%), household exposure (1-10%), occupational exposure (1-2%), or hemodialysis (20%) have become infected with HCV, the highest rates of transmission are via parenteral routes.3,9 In Canada, transfusion of blood or blood products, transplantation of organs from infected donors, and sharing of contaminated needles among IDUs were the most efficient means for transmitting HCV.9" Since 1990, all blood donors in Canada have been screened for antiHCV, virtually eliminating the possibility of infection via this route.12 IDU now represents the risk behaviour associated with the great majority of incident HCV infections in Canada.9,13,11
The prevalence of HCV in Canada is currently estimated to be approximately 0.8% (0.68%-0.94%), with 0.96% in males and 0.53% in females.15Those in age groups <5 years, 6-14 years, 15-19 years, 20-39 years, 40-64 years, and 65+ were estimated to have a prevalence of 0. …