No abstract

To assess the risk of hepatitis C in Canada and to predict the burden that this disease may pose to the Canadian society in the near future, expected numbers of persons at different stages of the disease currently and in the next decade were estimated by simulation using a published hepatitis C natural history model with no treatment effect being applied. Based on the estimate of 240,000 persons who are currently infected with the hepatitis C virus in Canada, the simulation analysis demonstrated that the number of hepatitis C cirrhosis cases would likely increase by 92% from 1998 to the year 2008. It was also projected that the number of liver failures and hepatocellular carcinomas related to hepatitis C would increase by 126% and 102%, respectively, in the next decade. The number of liver-related deaths associated with hepatitis C is expected to increase by 126% in 10 years. The medical and social care systems in Canada may not be ready to support these large increases. These results highlight the importance of both the control of disease progression of hepatitis C virus-infected persons and the primary prevention of hepatitis C infections in Canada.

OBJECTIVE:To assess the incidence and risk factors for acute hepatitis B and acute hepatitis C in a defined Canadian population. PATIENTS AND METHODS: An enhanced surveillance system was established in October 1998 to identify cases of acute hepatitis B and C infections in four regions in Canada, with a total population of approximately 3.2 million people. Information on demographic and clinical characteristics, laboratory results and potential risk factors was collected using predefined questionnaires. RESULTS: A total of 79 cases of acute hepatitis B and 102 cases of acute hepatitis C were identified from October 1998 to December 1999, resulting in an incidence rate of 2.3 and 2.9/100,000 person-years, respectively. Males had higher incidence rates than females. The incidence of acute hepatitis B peaked at age 30 to 39 years for both males and females, whereas acute hepatitis C peaked at 30 to 39 years for males and 15 to 29 years for females. At least 34% of acute hepatitis B and 63% of acute hepatitis C were associated with injection drug use. Persons who were 15 to 39 years of age were more likely to report injection drug use as a risk factor. Heterosexual contact was reported to be a risk factor for 36.6% of acute hepatitis B cases and 3.5% of acute hepatitis C cases. CONCLUSIONS: The surveillance provides national incidence estimates of clinically recognized acute hepatitis B and C. Both hepatitis B and C are important public health threats to Canadians. Prevention efforts for both diseases should focus on injection drug use, especially for people aged 15 to 39 years. Risky sexual behaviour is also a major concern in prevention of hepatitis B in Canada.

Between December 2016 and April 2017, two cases of invasive Group A Streptococcus (GAS) infections were reported at a Canadian military training facility. An outbreak was declared and a field investigation was launched to characterize the outbreak and identify associated risk factors to limit transmission. Throat culture data from military personnel at the garrison were analyzed. Investigators tracked invasive GAS cases and non-invasive hospitalized GAS cases, and conducted site visits and case interviews. Sensitivity and specificity for a rapid antigen detection test were evaluated. Molecular typing and phylogenomic relationships of outbreak isolates were analyzed using whole-genome sequencing. During this outbreak, four invasive cases were reported and six non-invasive cases were hospitalized. In a sample of 705 throat cultures examined, 35.2% were GAS-positive. Among 65 platoon contacts of one invasive case, 30.2% were GAS-positive. Reluctance to seek medical care, challenges in following cough etiquette, and low compliance with antibiotics were identified among recruits. The rapid antigen detection test had low sensitivity (31.6%) during the outbreak. The outbreak sequence type was emm6.4 and outbreak isolates were highly related phylogenetically, differing by 0-4 single nucleotide variants. This is the first report of a GAS outbreak among Canadian military trainees. Increased surveillance of GAS infections, increased control measures and outbreak-specific clinical guidelines were implemented in-garrison. No further invasive GAS cases were identified. A GAS surveillance system was implemented and efforts to improve antibiotic compliance and medical consultation were recommended.

In a sentinel hepatitis surveillance study conducted by sentinel health units, 1469 patients were enrolled, and 959 (65.3%) were positive for antibody to hepatitis C virus (HCV). Samples from 387 patients (40.4%) were tested for HCV RNA, and 289 (74.7%) were positive for RNA. The major risk factor for HCV infection was injection drug use, reported in 71% of cases. The genotyping of HCV isolates showed that subtype 1a (48%) was predominant in Canada. The other subtypes detected were 1b (19%), 2a (6%), 2b (3%), 3a (22%) and 4a (1%). In Winnipeg, Manitoba, subtype 3a (47%) was more prevalent than subtype 1a (37%), and, in Guelph, Ontario, both subtypes 1a and 3a had equal (40%) distribution. The prevalence of subtype 3a was significantly higher in injection drug users (27%) than in nonusers (10%) (P<0.005). In Canada, injection drug use is the major risk factor for HCV infections, and subtype 1a is more prevalent.