HIV and AIDS in Canada

Surveillance Report to December 31, 2000

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Information to the readers of HIV and AIDS in Canada

The Divisions of HIV/AIDS Epidemiology and Surveillance and of Retrovirus Surveillance from the Bureau of HIV/AIDS, STD and TB at the Centre for Infectious Disease Prevention and Control (CIDPC), Health Canada, are pleased to provide you with HIV and AIDS in Canada: Surveillance Report to December 31, 2000.

The Division of HIV/AIDS Epidemiology and Surveillance is responsible for all data analyses, writing and coordination of the publication of this report. This Division works in close collaboration with the Division of Retrovirus Surveillance, which collects HIV and AIDS surveillance data.

Since our last edition, we have made significant changes to the report. Some of these changes include i) the merging of both official languages into one report; ii) an expanded commentary section, entitled At a Glance, highlighting trends in HIV/AIDS in Canada; iii) a simplified Technical Notes section; iv) a glossary of useful epidemiology and surveillance terminology; and v) 5-year age groupings for AIDS data to be consistent with age groups used by UNAIDS.

A significant finding in this surveillance report is that, after adjustment for reporting delay, the annual number of reported AIDS cases increased in 2000 for the first time since 1994. We will be watching this trend carefully to see whether it continues when further data are available and a more precise adjustment for reporting delay is possible. Another finding to note in this report is the increase in both the reported number and relative proportion of positive HIV tests attributed to men who have sex with men. This confirms the trend observed in the semi-annual report to June 30, 2000 and in part corroborates the increase in HIV incidence seen in this group in the 1999 national HIV estimates produced by the Bureau.

It is hoped that the improvements noted above will make the report more understandable and easier to use. We continue to welcome and appreciate your comments and suggestions.

Yours sincerely,

Chris Archibald, MDCM, MHSc, FRCPC Chief Division of HIV/AIDS Epidemiology and Surveillance

Peter Uhthoff, MD, MSc Acting Chief Division of Retrovirus Surveillance

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Table of Contents

HIV/AIDS Surveillance - At a glance
TABLES
SECTION I HIV in Canada: Positive HIV Test Reports to December 31, 2000, and Reported to CIDPC up to March 2, 2001
1.	Number of positive HIV test reports by year of test
2.	Cumulative number of positive HIV test reports occurring in adults and children by gender between November 1, 1985, and December 31, 2000
3A.	Number of positive HIV test reports among males by age group and year of test
3B.	Number of positive HIV test reports among females by age group and year of test
3C.	Number of positive HIV test reports by age group and year of test
4A.	Number of positive HIV test reports among adult males (>= 15 years) by exposure category and year of test
4B.	Number of positive HIV test reports among adult females (>= 15 years) by exposure category and year of test
4C.	Number of positive HIV test reports among adults (>= 15 years) by exposure category and year of test
4D.	Number of positive HIV test reports among children (< 15 years) by exposure category and year of test
4E.	Number of positive HIV test reports by exposure category and age group between January 1, 2000, and December 31, 2000
5A.	Number of positive HIV test reports by province/territory and gender between November 1, 1985, and December 31, 2000
5B.	Number of positive HIV test reports by province/territory and year of test
6.	Number of positive HIV test reports by exposure category and province/territory between January 1, 2000, and December 31, 2000
SECTION II Report of the Canadian Perinatal HIV Surveillance Program, 1984-2000
7.	Cumulative number of perinatal HIV-exposed infants by geographic region and current status, 1984-2000
SECTION III AIDS in Canada: AIDS Surveillance to December 31, 2000, and reported to CIDPC up to March 2, 2001
8.	Number of reported AIDS cases by year of diagnosis and adjusted for reporting delay to December 31, 2000
9.	Number of reported adult AIDS cases (>= 15 years) by year of diagnosis and gender
10.	Cumulative number of reported AIDS cases occurring in adults and children by gender up to December 31, 2000
11A.	Number of male AIDS cases by age group and year of diagnosis
11B.	Number of female AIDS cases by age group and year of diagnosis
11C.	Number of AIDS cases by age group and year of diagnosis
12A.	Number and percentage distribution of adult male AIDS cases (>= 15 years) by exposure category and year of diagnosis
12B.	Number and percentage distribution of adult female AIDS cases (>= 15 years) by exposure category and year of diagnosis
12C.	Number and percentage distribution of adult AIDS cases (>= 15 years) by exposure category and year of diagnosis
12D.	Number and percentage distribution of AIDS cases among children by exposure category and year of diagnosis
12E.	Total number of AIDS cases among adults (>= 15 years), by exposure category and age group up to December 31, 2000
12F.	Total number of AIDS cases in children by exposure category and age group up to December 31, 2000
13A.	Number of AIDS cases by province/territory and gender up to December 31, 2000
13B.	Number of male AIDS cases (all ages) by province/territory and year of diagnosis
13C.	Number of female AIDS cases (all ages) by province/territory and year of diagnosis
13D.	Number of AIDS cases (all ages) by province/territory and year of diagnosis
14.	Number and percentage distribution of all AIDS cases by province/territory and exposure category to December 31, 2000
15.	Number of AIDS cases by year of diagnosis and ethnic status
16.	Number of deaths due to AIDS among adults and children by year of death
SECTION IV International Statistics on AIDS
APPENDICES
Appendix 1. Technical Notes Appendix 2. Data Limitations Appendix 3. Terminology Appendix 4. References Appendix 5. Data Sources

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At a Glance

Introduction

This section highlights the main findings observed in the HIV and AIDS surveillance data reported by Canadian provinces and territories to the Centre for Infectious Disease Prevention and Control (CIDPC) up to December 31, 2000. It is important to note that reported positive HIV tests and AIDS cases as presented in this surveillance report represent only those individuals who seek testing and/or medical care. The number of positive HIV test reports provides a description of those who came forward for testing, were diagnosed and reported HIV positive. It does not, however, represent the total number of individuals living with HIV (prevalence) or newly infected each year (incidence). Similarly, the number of reported AIDS cases represents those who sought medical care, were diagnosed with AIDS and were reported to CIDPC. The number of reported AIDS cases, therefore, does not represent true AIDS incidence.

The Bureau of HIV/AIDS, STD and TB has produced estimates of HIV prevalence to the end of 1999 and HIV incidence in 1999. These estimates were produced using a combination of methods, incorporating data from a wide variety of sources, including HIV test reports, AIDS case reports, population-based surveys, targeted epidemiological studies and census data^1,2. It is estimated that at the end of 1999 there were approximately 49,800 people in Canada living with HIV (including those living with AIDS) and 4,190 newly infected with HIV in 1999. Furthermore, an estimated 15,000 were living with HIV but were unaware that they were infected and are consequently not represented in the HIV surveillance data³. Further information on the methodology and results of these estimates are available in the referenced reports.

HIV Surveillance Data

There have been 48,014 positive HIV tests reported to CIDPC since such reporting to Health Canada began, in November 1985 (Table 1).

There were 2,104 positive HIV tests reported to CIDPC in 2000. The number reported has slowly declined each year from 2,983 positive reports in 1995 to 2,772, 2,537, 2,330, and 2,240 in 1996, 1997, 1998 and 1999 respectively. Figure 1 outlines the trend in the number of positive HIV tests reported by province and region as well as at the national level (Table 5b).

FIGURE 1
Number of positive HIV test reports by province/region and year of test

Adult females account for 13.8% of reported positive HIV tests with known age and gender up to December 31, 2000. The proportion of females among adult positive HIV test reports with known gender increased from 18.8% in 1995 to about 24% in 1999 and 2000 (Tables 3A and 3B).

With regard to HIV surveillance data by age, the largest proportion of positive HIV tests are consistently reported in the 30-39 year age group (Tables 3C). In 2000, this age group represented 41.1% of positive HIV test reports with known age. It is important to note, however,  that positive HIV test reports represent new HIV diagnoses and not new infections. Consequently, the largest proportion of new infections will be among a younger age group.

There was a steady increase in the proportion of positive HIV test reports among the heterosexual exposure category up to 1999. This proportion increased from 7.5% of all positive HIV test reports among adults with known exposure in 1985-1994 to 28.5% in 1999. There was a slight decrease, to 25.4%, in the proportion attributed to heterosexual contact in 2000 (Table 4C).

Among adults 15 years old and over, the number of positive test reports attributed to the exposure category men who have sex with men (MSM) decreased by 38.0% from 677 test reports in 1995 to 420 in 1999, and increased by 10.2% to 463 positive HIV tests in 2000 (Table 4C). The proportion of positive reports decreased from 74.6% during the period 1985-1994 to about 37% during 1997-1999 and  increased to 42.3% in 2000.

Positive HIV test reports among adults attributed to injecting drug use (IDU) increased from 450 in 1995 to 496 in 1996 and decreased by 42.7% to 284 test reports in 2000. The proportion attributed to IDU increased from 8.9% in 1985-1994 to a peak of 33.8% in 1996. This proportion decreased in 2000 to 26.0% (Table 4C).

The increase in both the reported number and the relative proportion of positive HIV tests attributed to MSM in part corroborates the increase in HIV incidence seen in this group in the 1999 national HIV estimates produced by the Bureau. Similarly, the decrease in reported positive HIV tests and relative proportion represented by IDU substantiates the finding from the recent estimates that incidence among IDUs has decreased slightly since 1996.

AIDS Surveillance Data

There have been 17,594 AIDS cases reported to CIDPC since the beginning of the epidemic in the early 1980s (Table 8). The annual number of AIDS diagnoses, after adjustment for reporting delay, reached a peak in the early 1990s and steadily declined between 1994 and 1999 (Figure 2 and Table 8). The rate of decline slowed in 1997, and in 2000 the number of AIDS diagnoses adjusted for reporting delay increased again. A more detailed description of the trends in reported AIDS cases (not adjusted for reporting delay) by province or region over the last decade is seen in Figure 3.

FIGURE 2
Reported AIDS cases and AIDS cases adjusted for reporting delay by year of diagnosis

FIGURE 3
Reported AIDS cases (not adjusted for reporting delay) by province or region and year of diagnosis

A major factor in the decline in AIDS cases (as seen in Figure 2) during the late 1990s was the delayed or prevented onset of AIDS opportunistic infections with the use of highly effective antiretroviral therapy since 1996. Other possible factors include delayed and under-reporting of AIDS diagnoses. Reasons for the declining rate of decrease from 1997 to 1999 and the increase in AIDS cases adjusted for reporting delay in 2000 remain unclear. Possible issues include the development of resistance to antiretrovirals and the uncertain duration of the drug effects. The Bureau will continue to monitor whether this trend continues as further data become available and a more precise adjustment for reporting delay is possible.

Adult females account for 7.7% of the total cumulative reported AIDS cases with known age and gender up to December 31, 2000. The proportion of females among adult AIDS cases increased from 5% during the period 1979-1990 to 16% in 1999, and dropped to 11% in 2000 (Table 11). The proportion of AIDS case among Aboriginal ethnic groups has been increasing since 1992 (1.7%) and reached a peak in 1999 (11.0%). In 2000, this proportion decreased slightly to 9.2% of all AIDS cases (Figure 4 and Table 15). Similarly, Black ethnic groups represented 6.9% of all AIDS cases with ethnic group reported in 1991, and rose to 15.0% in 1999 followed by a decrease to 8.3% in 2000.

FIGURE 4
Proportion of reported AIDS cases by selected ethnic group

Many AIDS cases for 2000 have not yet been reported. Therefore, the data are too preliminary to know whether the decreases seen in 2000 in the proportion of reported AIDS cases among Aboriginal persons, Black ethnic groups and females are genuine. These findings will require further monitoring as more surveillance data become available.

The trends observed in the distribution of exposure categories of diagnosed AIDS cases are similar to those of positive HIV test reports and are presented in Figure 5.

FIGURE 5
Exposure categories as a percentage of adult AIDS cases

Interpretation

These current findings underscore the importance of monitoring the changing HIV/AIDS epidemic. As the epidemic continues to evolve, so does the need for HIV and AIDS surveillance. The Bureau continues to work in close collaboration with its partners in the provinces and territories to improve the quality of the data. Furthermore, the Bureau of HIV/AIDS, STD and TB appreciates the increasing need to broaden the scope of surveillance through enhancement of the collection of relevant data related to HIV infection and risk behaviour.

Note: Please refer to the Appendices for an explanation of the exposure categories (Appendix 1), a discussion of the limitations of the data (Appendix 2) and the terminology (Appendix 3) used in this report.

References

1 Geduld J, Archibald C. National trends of AIDS and HIV in Canada.CCDR 2000;26:193-201.

2 Health Canada. HIV/AIDS Epi Update. National HIV prevalence and incidence estimates for 1999: no evidence of a decline in overall incidence. Bureau of HIV/AIDS, STD and TB, Centre for Infectious Disease Prevention and Control, Health Canada, May 2001.

3 Health Canada. HIV/AIDS Epi Update. Prevalent HIV infections in Canada: up to one-third may not be diagnosed. Bureau of HIV/AIDS, STD and TB, Centre for Infectious Disease Prevention and Control, Health Canada, May 2001.