This graph shows the annual number of IMD cases in columns, the annual age-standardized incidence rate in solid lines, and the annual crude incidence rate in dash lines. From 2006 to 2011, a total of 1174 IMD cases were reported in Canada, ranging from 154 to 229 cases. The incidence rates are per 100,000 population. Although age-standardized incidence rates are relatively higher than the corresponding crude rates, age-standardization does not change the order of magnitude of the rates. The mean crude and age-standardized incidence rates were 0.58 and 0.60, respectively. The age-standardized incidence rate of IMD in 2010 (0.47, CI: 0.39-0.54) was significantly lower than in 2006 (0.70, CI: 0.61-0.80), 2007 (0.73, CI: 0.63-0.82) and 2009 (0.67, CI: 0.58-0.76). There were no significant differences identified in other year comparisons.
The graphs shows annual age-standardized incidence rate of IMD by province/territory and year in columns and mean age-standardized incidence rate by province/territory in dots. IMD cases were reported in all provinces and territories in Canada, but not every year during the study period. Prince Edward Island and Yukon Territory only reported IMD cases in 2009 and 2010, respectively. Nunavut and Northwest Territory only reported IMD cases in 2006 and 2011. Although Nunavut had the highest incidence rate of 4.09 in 2006, the mean age-standardized incidence rate for Quebec (1.12, CI: 0.95-1.29) was significantly higher than any other province/territory except Newfoundland & Labrador (1.08, CI: 0.0.53-1.64) during the study period. Among other province comparisons, the mean age-standardized incidence rates varied but not significantly.
The graph shows age distribution of IMD cases overall and IMD cases by serogroup (B, C, W-135 and Y) in 100% stacked columns. The median age for serogroups B, W-135, and C and Y shifted from age groups 15-19 years to 30-39 years to 40-59, respectively. While only accounting for 6% of the total population, children under 5 years accounted for 37% of serogroup B cases, 31% of serogroup W-135 cases, but only 9% of serogroup C and 10% Y cases. Among children under than 5 years, Infants less than 1 year accounted for more than half of the serogroup B, C and Y cases but only 16% of serogroup W-135 cases. People over 40 years accounted for the majority of serogroup C (51%) and Y (59%) cases, near half of serogroup W-135 (48%), but only 21% of serogroup B cases.
The graph shows IMD serogroup proportions by year. From 2006 to 2011, the proportion of serogroup B cases among all IMD cases was the highest every year during the study period, and ranged from 50% to 62% of cases. The proportion of serogroup C cases decreased from 20% in 2006 to 2% in 2011. It was significantly higher than serogroup W-135 from 2006 (p<0.001) to 2008 (p=0.02); the difference was no longer significant from 2009 to 2011. Conversely, the proportion of serogroup C cases became significantly lower than serogroup Y in 2010 (p=0.004) and 2011 (p<0.0001). The proportion of serogroup Y cases increased gradually from 13% in 2006 to 21% in 2011, the age-standardized incidence rates for this group did not change significantly over the study period (range 0.07 to 0.10). The proportion of serogroup Y remained significantly higher than that of serogroup W-135 from 2006-2011. Serogroup W-135 cases accounted for 3% to 7% during the study period.