Brief Report on Sexually Transmitted Infections in Canada: 2006

Technical Notes:

Case reporting: Currently, some jurisdictions report to PHAC using aggregate case counts rather than through case by case reporting. Furthermore, only the following variables are submitted by all 13 jurisdictions: age of diagnosis, year of diagnosis, province/territory of diagnosis, and sex. National reporting is therefore limited to analyses of the variables that are submitted to PHAC.

Reporting delay: There may be a delay between the time when a person tests positive for an STI and when the report is received at PHAC. This time lag is referred to as reporting delay.  In cases where there are discrepancies between data reported by PHAC and those reported by individual provinces and territories, provincial/territorial data should be considered to be more accurate as they are the most current.  Also note that 2006 data are preliminary and subject to change. 

Underreporting:  The number of reported cases likely underestimates the true burden of infection in a given population because:

• many people who are infected with STIs do not exhibit symptoms; and
• an infected individual must interact with the medical system in order to get tested and have a positive laboratory results for a bacterial STI.

Annual trends: Observed trends must be interpreted with caution since there are number of factors that contribute to changes:

• rates based on small numbers are more prone to fluctuation over time; and
• there may be changes to testing patterns due to improved diagnostic capabilities, improved duplicate removal, and reporting delay. 

2005 data:  Reported cases for Ontario in 2005 are underestimates due to transition in the provincial reporting system. Decreases for 2005 are likely an artifact of reporting delay, not a true reduction in disease incidence. Canadian cases and rates for 2005 are affected.

Population data:  Statistics Canada, Demography Division, Demographic Estimates Section, July Population Estimates, 1997-2000 final intercensal estimates, 2001-2003 final postcensal estimates, 2004-2005 updated postcensal estimates, 2006 preliminary postcensal estimates.)

References

1. Public Health Agency of Canada. Canadian Guidelines on Sexually Transmitted Infections (STI) 2008 Edition: PHAC, 2008. http://www.phac-aspc.gc.ca/std-mts/sti_2006/sti_intro2006-eng.php
2. Fleming DT, Wasserheit JN. From epidemiological synergy to public health policy and practice: the contribution of other sexually transmitted diseases to sexual transmission of HIV infection. Sex Transm Infect 1999;75:3-17.
3. Holmes KK, Mardh PA, Sparling PF et al. Sexually transmitted diseases 3rd ed. Mcgraw-Hill
4. Manitoba Health. The descriptive epidemiology of sexually transmitted infections (STI) and blood-borne pathogens in Manitoba: 2002-2003. Manitoba Health . 2008.
5. Gratix J, Honish L, Mashinter L, et al. Case series descriptive analysis of a primary syphilis outbreak in Edmonton, Alberta, July 2004-April 2006. Can Commun Dis Rep 2007 Mar;33(6):61-7.
6. Jayaraman GC, Read RR, Singh A. Characteristics of individuals with male-to-male and heterosexually acquired infectious syphilis during an outbreak in Calgary, Alberta, Canada. Sex Transm Dis 2003 Apr;30(4):315-9.
7. Ogilvie G, Knowles L, Wong E, et al. Incorporating a social networking approach to enhance contact tracing in a heterosexual outbreak of syphilis. Sex Transm Infect 2005 Apr;81(2):124-7.
8. Singh AE, Sutherland K, Lee B, et al. Resurgence of early congenital syphilis in Alberta. CMAJ 2007 Jul;177(1):33-6.
9. Patrick DM, Rekart ML, Jolly A, Mak S, Tyndall M, Maginley J, Wong E, Wong T, Jones H, Montgomery C, Brunham RC. Heterosexual outbreak of infectious syphilis: epidemiological and ethnographic analysis and implications for control. Sex Transm Infect 2002 Apr;78 Suppl 1:i164-i169.
10. Régie Régionale de la Santé et des Services Sociaux de Montréal-Centre. Bacterial STIs make a comeback! Prévention en practique médicale . 2002. 9-24-0080.
11. Toronto Public Health. Infectious syphilis on the rise in Toronto - information for health care providers. Toronto Public Health . 2005.
12. Wheeler C. Surge in syphilis prompts warning: disease breaks out among users of gay bathhouses. Ottawa Citizen 2001 Mar 28.