Appendix A: Report on Sexually Transmitted Infections in Canada: 2012 – Technical notes

Appendix A: Technical Notes

Case definitions

Case definitions for communicable diseases under national surveillance can be found online at Case definitions for communicable diseases under national surveillance.

Reporting formats

Currently, some jurisdictions report to the Agency using aggregate counts instead of case reporting. The following selected variables are submitted by all 13 jurisdictions: age at diagnosis, year of diagnosis, province/territory of diagnosis, and sex. National reporting is therefore limited to analysis of these variables.

Underreporting

The number of reported cases likely underestimates the true burden of infection in a given population for a variety of reasons. For example, many people who are infected with STIs do not have symptoms and therefore may not go to a health care practitioner for testing.

Data sources

Canadian Notifiable Disease Surveillance System (CNDSS): The CNDSS contains data on nationally notifiable infectious diseases reported by provincial and territorial health authorities. The content of the various data submissions depends on each jurisdiction's ability to collect the data elements, privacy legislation, and technological capacity. Data are submitted in a variety of formats (e.g., line-listed electronic, paper-based case reports, or aggregate data) and are verified and loaded into the national Canadian Notifiable Disease Surveillance System (CNDSS) by Agency personnel. Extracts from CNDSS are used as the basis of national data tables and surveillance reports. In cases for which there are discrepancies between data reported by the Agency and those reported by individual provinces and territories, provincial/territorial data should be considered to be more accurate as they are the most current.

LGV enhanced surveillance system: In response to the emergence of LGV in Europe, Canada initiated enhanced surveillance of this STI in 2005. Confirmatory testing for suspected LGV cases is performed by the National Microbiology Laboratory (NML). Where possible, provincial/territorial health authorities use a standardized national case report form to collect enhanced epidemiological data on each case and submit the data to the Agency.

National Neisseria gonorrhoeae Surveillance Program: Provincial public health laboratories voluntarily submit N. gonorrhoeae isolates to the NML when the provincial laboratories identify resistance to at least one antibiotic or if the provincial laboratories do not perform any antimicrobial susceptibility testing. The total number of isolates cultured in each province is used as the denominator for proportion resistance calculations.

Population denominators: Statistics Canada, Demography Division, Demographic Estimates Section, July Population Estimates, 1997-2005 final intercensal estimates, 2006-2008 final postcensal estimates, 2009-2010 updated postcensal estimates, 2011 preliminary postcensal estimates.

Live birth data: Statistics Canada, Canadian Vital Statistics, Birth Database, 2005-2012.