Supplement

2004 Canadian Sexually Transmitted Infections Surveillance Report

Canada Communicable Disease Report
Volume: 33S1 - May 2007

Full version: PDF Version
69 pages (7.93 MB)

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Table of Contents

• Forward
• Acknowledgements
• Executive Summary
• Introduction
• Editorial - What if it all means something? The consequences of high rates of chlamydia in Canada
  • Pelvic Inflamatory Disease
  • Ectopic pregnancy
  • Infertility
  • Mental health
  • Prevention
• STI in the International Context
  • Comparison of international STI trends
  • STI strategies in the UK, the US and Canada
  • Emerging International STI issues
• Genital Chlamydia (Chlamydia trachomatis)
  • Sex and age distribution
  • Geographic distribution
  • Geographic and sex distribution
  • Discussion
• Gonorrhea (Neisseria gonorrhoeae)
  • Sex and age distribution
  • Geographic distribution
  • Geographic and sex distribtution
  • Neisseria gonorrhoeae antimicrobial resistance
  • Discussion
• Infectious Syphilis (Treponema pallidum)
  • Sex and age distribution
  • Geographic distribution
  • Geographic and sex distribution
  • Congenital syphilis
  • Discussion
• Viral STIs and Enhanced Surveillance
  • Viral STI
  • Enhanced surveillance
  • STI in street youth: Enhanced Surveillance of Canadian Street Youth (E-SYS)
• Projected Trends of STI in Canada
  • Methods
  • Results
  • Discussion
• Technical Notes
  • Commonly used terms/definitions
  • National surveillance of sexually transmitted infections (STIs)
• References
• Appendix I

Table 1.1	Reported Genital Chlamydia Cases and Rates in Canada by Age Group and Sex, 1991-2004
Table 1.2	Reported Genital Chlamydia Cases and Rates in Canada by Province/Territory and Sex, 1991-2004
Table 2.1	Report Gonorrhea Cases and Rates in Canada by Age Group and Sex, 1980-2004
Table 2.2	Reported Gonorrhea Cases and Rates in Canada by Province/Territory and Sex, 1980-2004
Table 3.1	Reported Infectious Syphilis Cases and Rates in Canada by Age Group and Sex, 1993-2004
Table 3.2	Reported Infectious Syphilis Cases and Rates in Canada by Province/Territory and Sex, 1993-2004

• Appendix II
  • Canada Map

Foreword

The Surveillance and Epidemiology Section of the Public Health Agency of Canada is pleased to provide you with the latest version of the Sexually Transmitted Infections (STI) Surveillance Report. This report summarizes trends in the three nationally notifiable bacterial STIs (genital chlamydia, gonorrhea and infectious syphilis) using data reported to the Public Health Agency of Canada by the provinces and territories. To provide a more complete picture of the burden of STIs in Canada, viral STI rates and the results of enhanced surveillance initiatives are included in the report. Finally, Canadian STI rates are given some context through a comparison with the rates of similar countries.

Although there have been efforts towards improving prevention, education and health promotion surrounding STIs in this country, clearly, transmission is not being controlled. Over 60,000 cases of genital chlamydia are reported every year in Canada, and young women are disproportionately affected, for many of whom infertility is a consequence. Syphilis and lymphogranuloma venereum have infected hundreds of Canadians so far, including a large proportion that are also infected with HIV. This is but one example of how many STIs increase the transmission and acquisition of HIV. The challenges faced in targeting the most vulnerable populations and a failure to properly educate our youth about sexual risks related to STIs adds further fuel to the fire.

In addition to the efforts made to avert new STI infections, STI prevention and control needs to be a key tool for preventing the spread of HIV. Investment in a comprehensive national strategy to address sexually transmitted and bloodborne infections will be needed to curb the escalating STI epidemic and save health care dollars downstream. Most importantly, efforts that result in averted infections and reduced morbidity will ultimately improve the health of Canadians.

Acknowledgements

This report was prepared by the Surveillance and Epidemiology Section, Community Acquired Infections Division, Centre for Infectious Disease Prevention and Control, Public Health Agency of Canada (PHAC). Many others contributed to its development and publication:

• the Sexual Health and Sexually Transmitted Infections Section through its thorough review of the document and valuable input and suggestions;
  
• other members of the Community Acquired Infections Division through their administrative and technical assistance;
  
• the Scientific Publications and Multimedia Services Division, PHAC, which edited and published the report;
  
• Dena Schanzer, who developed the projections;
  
• Janice Mann, who eloquently addressed the broad implications of rising chlamydia rates; and,
  
• the Public Health Library staff of Health Canada through their assistance with the literature review.

The ongoing national surveillance of sexually transmitted infections (STIs) requires the cooperation and commitment of many individuals and organizations:

• provincial and territorial ministries of health. We gratefully acknowledge them for the timely manner in which they provide data to the PHAC and their continued expert contributions to the national STI program;
  
• local public health units across the country with their continued commitment to collecting the data that form the basis of national surveillance;
  
• the Surveillance and Risk Assessment Division within the PHAC, which is responsible for national surveillance of HIV and AIDS and which maintains the Infectious Disease Reporting System from which counts of bacterial STI are derived;
  
• the National Microbiology Laboratory in Winnipeg, which provides data on antibiotic-resistant gonorrhea and also contributed to sections of this report; and
  
• the Field Surveillance Officers, located in several provinces and territories, who assist with data quality improvement and provide ongoing support to the Community Acquired Infections Division.

Executive Summary

This report confirms that sexually transmitted infections (STIs) are an escalating public health concern and challenge in Canada. Since 1997, reported rates of genital chlamydia and gonorrhea have been steadily increasing. Rates of infectious syphilis began to increase slowly in 1997 and then rose rapidly from 2000 onwards. As of 2004, all three reportable bacterial STIs are continuing their upward climb, affecting more and more Canadians.

The observed increase in the number of reported bacterial STI cases is not unique to Canada: there are some similarities between our country and both the United Kingdom and the United States in this respect. Chlamydia is the most commonly reported STI in each country, affecting similar age groups between the sexes, and it is on the rise. With respect to syphilis, a common epidemiologic factor among these countries is the occurrence of outbreaks among men who have sex with men (MSM). Unlike the first two infections, however, gonorrhea appears to be increasing only in Canada.

Genital chlamydia remains the most commonly reported STI and notifiable disease in Canada. The overall chlamydia rate in 2004 demonstrated a 70% increase from 1997; the rate of gonorrhea rose by 94%. Gonococcal resistance to first-line treatment options is an emerging problem. Infectious syphilis has seen the most staggering increase with a 9-fold rise in rates for this same period (Table 1).

Table 1. Reported cases and rates of bacterial STIs in Canada

	Genital chlamydia		Gonorrhea		Infectious syphilis1
	Cases	Rate2	Cases	Rate2	Cases	Rate2
1997	34,144	113.9	4,477	14.9	115	0.4
2002	56,266	179.4	7,365	23.5	482	1.5
20043	62,971	197.1	9,233	28.9	1,127	3.5
1 Infectious syphilis: primary, secondary and early latent stages 2 Rate per 100,000 population 3 2004 numbers are preliminary, and changes are anticipated; Nunavut data unavailable.

The burden of STIs in Canada is not uniformly distributed throughout the population. Young women continue to be disproportionately affected by genital chlamydia, and gonorrhea infection is concentrated in males aged 20 to 29 years. Males over the age of 30 account for the majority of infectious syphilis cases. Marked geographic differences are also seen with rates of genital chlamydia and gonorrhea being highest in the north, followed by Manitoba and Saskatchewan. Infectious syphilis rates are highest in British Columbia. Ontario, not surprisingly given its large population, reports the greatest number of cases for all three notifiable STIs.

These three infections account for over half of all notifiable diseases reported to the Public Health Agency of Canada (Figure 1). This comparison paints a clear picture of the burden of disease directly attributable to STIs, which is further augmented by the significant morbidity and sequelae of some other sexually transmissible infections.

• Sexual transmission accounts for a significant proportion of reported cases of HIV. The number of positive test reports has remained relatively constant, at around 2,500 per year, with almost half of these diagnoses occurring in MSM.
  
• Human papillomavirus (HPV) and herpes simplex virus are both considered highly prevalent infections in the Canadian population. High-risk strains of HPV may cause abnormal Pap smears in women, are the major cause of cervical cancer, and may lead to anogenital cancers in both men and women. Some non-oncogenic HPV strains may cause anogenital warts. The presence of herpetic ulcers facilitates the transmission of HIV.
  
• Lymphogranuloma venereum, an emerging STI in Canada, may lead to significant sequelae. All reported cases have been male, with high rates of HIV co-infection.

Some high-risk populations may not be captured in routinely reported STI numbers. Enhanced surveillance initiatives provide an indication of the specific burden of disease in such populations, helping to guide prevention and control efforts. For example, the Enhanced Surveillance of Canadian Street Youth (E-SYS) demonstrates that street youth have much higher rates of bacterial STIs than youth in the general Canadian population.

Rates of chlamydia and gonorrhea were projected for the years 2005 to 2010 to provide a concrete example of what STI rates in Canada may look like in the absence of a substantive shift in the epidemic. If current trends persist, rates will reach even more daunting heights by the end of this decade. Since co-infection with multiple viral or bacterial STIs is common, especially in high-risk populations, factors that cut across infections need to be taken into consideration when developing public health interventions.

These figures have tangible implications for the Canadian population. An increasing proportion of the population is at risk of acquiring (or transmitting) an STI. The emotional and social consequences of a diagnosed infection may present significant challenges for an individual. The repercussions of an untreated infection may be even more serious, given that long-term health concerns may develop as a result. These infections are entirely preventable but are also easily diagnosed and treated. Factors such as these favour the control of STIs in Canada and must be used to our advantage as we look towards the future.

Figure 1. Reported cases of bacterial STI as a proportion of all notifiable diseases in Canada, 2004*

* 2004 numbers are preliminary and changes are anticipated; Nunavut data unavailable.
Source: Notifiable Diseases, Surveillance and Risk Assessment Division, Public Health Agency of Canada, 2006.

Introduction

This publication focuses on basic epidemiologic information about bacterial infections that are transmitted predominantly through sexual contact and that are nationally reportable to the Public Health Agency of Canada (PHAC). The list of nationally reportable diseases is determined by a federal/provincial/territorial committee using a prioritysetting process to determine which diseases should be routinely monitored. Criteria were developed with the objective of establishing the most efficient allocation of resources in the prevention and control of diseases that pose a threat to Canadians. The sexually transmitted infections (STIs)¹ included on this list are genital chlamydia, gonorrhea and infectious syphilis. Other infections, such as genital herpes and human papillomavirus (HPV), are not nationally reportable. To provide a more complete picture of the burden of STIs in Canada, some non-reportable infections have been incorporated into this report, citing various research studies as a data source.

As the most commonly reported notifiable disease in Canada, chlamydia is responsible for a considerable proportion of the burden of disease. An invited commentary entitled "What If It All Means Something? The Consequences of High Rates of Chlamydia in Canada" further explores the implications of this seemingly innocuous and easily combatable bacterial infection.

This report on Canadian trends in STIs is intended for governments, health professionals, researchers and voluntary agencies that are involved in service provision and planning, as well as the general public. The goal is to provide information that can be used to support and guide decision-making and programs aimed at improving the health of Canadians. To further support this endeavour, a section projecting trends has been added.

Technical notes are provided to assist with data interpretation and to provide more detail on the surveillance system from which our data are extracted. The appendix contains data tables for each reportable STI and provides a breakdown of reported infection by age and sex, and province and sex.

All surveillance systems have limitations, and the following are those specifically noted for our system. Many STIs are asymptomatic, therefore some infections may go unnoticed, undiagnosed and unreported. Furthermore, contact tracing is a critical activity in the prevention and control of STIs, but recent increases in risky sexual behaviour, such as anonymous sex partnering, make contact tracing difficult. As a result, infections among anonymous contacts of cases may go unrecognized and therefore may not be captured by the surveillance system. Among symptomatic individuals, only those who seek testing or medical care will be counted. Because of these limitations, the counts in this report are likely an underestimate of the true burden of disease. However, the report does provide an estimate of the scope and trends of STIs in Canada over time. Data are subject to change as a result of reporting delays and other constraints common to surveillance systems.

When reading this report, please keep in mind that small variability may exist between data reported by the PHAC and data reported by individual provinces and territories. In such circumstances, provincial/territorial data are definitive, as these data are the most up to date.

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1. The term STI (sexually transmitted infection), now commonly used in place of STD (sexually transmitted disease), is more encompassing and includes infections that may be asymptomatic.

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Full version: PDF Version
79 pages (9.55 MB)