The Epidemiology of HIV in gay men and other men who have sex with men

This fact sheet provides a summary of the HIV epidemic in Canada among gay men and other men who have sex with men (MSM). It is one of a series of fact sheets that provide easy to use epidemiological information on the state of HIV infection in Canada.

All epidemiological information is approximate, based on the best available data. Most of the data in this fact sheet come from research studies, population-specific surveillance or national HIV estimates. More information about these data sources can be found in the section “Where do these numbers come from?” at the end of the fact sheet.

Like other populations, gay men and other men who have sex with men are at risk of HIV if they:

• have unprotected anal or oral sex (sex without a condom); and/or
• use non-sterile syringes/needles/equipment to inject drugs.

Based on a national health survey, approximately 2.1% of Canadian men self-identify as gay or bisexual.^[1]

In a nationally representative health survey, 2.1% of Canadian men aged 18 to 59 self-identified as gay or bisexual.^[1] If applied to the number of men in Canada aged 18 and older,^[2] this means that approximately 247,000 Canadian men identify as gay or bisexual. However, it is important to note that there may be additional men who engage in sex with men but do not consider themselves to be either gay or bisexual. Therefore, this number may under-represent the actual number of MSM in Canada.

Based on population-specific surveillance conducted in Canada, many gay men and other men who have sex with men engage in unsafe sexual practices that put them at risk of acquiring HIV.

It is difficult to know how many MSM engage in sexual behaviours that place them at risk of acquiring HIV because for many people, their sexual practices are private matters. The best evidence we have comes from population-specific surveillance that has been conducted in specific regions of Canada. However, it should be noted that sweeping generalizations cannot be made from studies that took place in different time periods and select locations.

Various studies have been done to evaluate one risky sexual behaviour: unprotected sex with a casual partner. These found that between 22% and 31% of MSM surveyed reported having unprotected anal sex with a casual partner in the six months prior to the survey.

• In a study in Victoria in 2007, 30% of MSM reported having unprotected anal sex with a casual male partner at least once in the six months prior to the survey.^[3]
• In a study in Vancouver in 2008, 31% of MSM reported having unprotected anal sex with a casual male partner at least once in the six months prior to the survey.^[4]
• In a study in Toronto in 2007, 28% of MSM reported having unprotected anal sex with a casual male partner at least once in the six months prior to the survey.^[5]
• In a study in Ottawa in 2007, 22% of MSM reported having unprotected anal sex with a casual male partner at least once in the six months prior to the survey.^[5]
• In a study in Montreal in 2005, 21% of MSM reported having unprotected anal sex with a casual male partner at least once in the six months prior to the survey.^[6]

Based on 2008 national HIV estimates, sex between men may have accounted for the HIV infection of 33,360 men (prevalence).^[7]

According to 2008 national estimates, sex between men may have accounted for the HIV infection of an estimated 33,360 MSM. This represents 51% of all people living with HIV.^[7] This estimate includes 31,330 men whose HIV infection was attributed to sex between men and an additional 2,030 men whose HIV infection may have been due to either sex between men or injection drug use as they reported a history of both behaviours at testing (Figure 1).^[7]

Figure 1. Estimated percentage of people living with HIV in Canada in 2008 by type of exposure to HIV

Based on national HIV estimates, an estimated 19% of gay men and other men who have sex with men who were living with HIV in 2008 were unaware they had it.^[7]

At the end of 2008, an estimated 19% of MSM living with HIV (or 6,000 MSM) remained undiagnosed.^[7]

Based on available research studies and population-specific surveillance in Canada, HIV prevalence among gay men and other men who have sex with men may range geographically from 3% to 24%.

It is hard to know exactly how many MSM in Canada are living with HIV. If we assume that there really are only 247,000 gay men in Canada and that the estimate of 33,360 MSM living with HIV is accurate (or at least approximate), then we can calculate that approximately 13.5% of MSM are living with HIV in Canada.

Another way to calculate how many MSM are HIV-positive is to examine research studies and population-specific surveillance that collect information from participants about their HIV status, either through self-report or through testing for HIV. These studies can tell us the approximate percentage of MSM living with HIV. Based on information from research and population-specific surveillance, HIV prevalence among MSM in Canadian cities may range from 11% to 24%.

• 18% of MSM who participated in a research study in Vancouver in 2008 tested positive for HIV.^[4]
• 13% of MSM who participated in a research study in Victoria in 2007 tested positive for HIV.^[3]
• 24% of MSM who participated in a research study in Toronto in 2007 tested positive for HIV.^[5]
• 12% of MSM who participated in a research study in Ottawa in 2007 tested positive for HIV.^[5]
• 13% of MSM who participated in a research study in Montreal in 2005 tested positive for HIV.^[6]
• 11% of MSM who participated in a research study in Halifax in 2005 self-reported being HIV-positive.^[8]

Based on national HIV estimates, an estimated 47% of all new cases of HIV in Canada in 2008 were in men who have sex with men.^[7]

An estimated 1,000 to 1,900 new HIV infections in 2008 were attributed to sex between men (44% of all new infections). The number of new infections in MSM has been stable since 2005.^[7]

An estimated 50 to 130 additional new HIV infections were attributed to either sex between men or injection drug use (3% of all new infections). This is similar to the estimated 40 to 130 new infections attributed to sex between men or injection drug use in 2005.^[7]

Key definitions

HIV prevalence

The total number of people who are living with HIV at a point in time. Prevalence tells us how many people have HIV.

HIV incidence

The number of new HIV infections in a defined period of time (usually one year). Incidence tells us how many people are getting HIV.

Where do these numbers come from?

Research studies

Studies that are undertaken as part of a research project to investigate the prevalence of HIV risk behaviours and/or HIV status are important tools to help us understand the epidemic within specific at-risk populations. These are conducted in various locations across Canada, usually spearheaded by researchers or community groups.

Population-specific surveillance

As part of the Federal Initiative to Address HIV/AIDS in Canada, PHAC monitors trends in HIV prevalence and associated risk behaviour indicators among key vulnerable populations identified in Canada through population-specific surveillance systems. These surveillance systems, also known as the “Track” systems, are comprised of periodic cross-sectional surveys conducted at selected sites within Canada.

M-Track is a national surveillance system of gay, bisexual and other men who have sex with men (MSM). Through this surveillance system, MSM participants complete a questionnaire and are tested for antibodies against HIV, hepatitis C and syphilis. As of December 31, 2009, a total of six sites had participated in M-Track across Canada. M-Track was first implemented in Montreal in 2005 (via linkage with the Argus Survey). Between 2006 and 2007, four additional sites joined M-Track: Toronto and Ottawa (Lambda Survey), Winnipeg and Victoria. More than 4,500 men participated in M-Track between 2005 and 2007. In 2008, Vancouver also implemented M-Track (ManCount Survey).

Limitations—For all the research studies referred to in this fact sheet, MSM from selected urban sites participated on a volunteer basis; therefore, the information presented does not represent all men who have sex with men in Canada.

Estimates of HIV prevalence and incidence

PHAC uses mathematical modeling techniques to provide an overall picture of the epidemic among both diagnosed and undiagnosed Canadians. These models combine statistics from many sources, including routine surveillance, population-specific surveillance and information about HIV-testing behaviours, data from treatment programs, and educated assumptions. PHAC publishes estimates of national HIV prevalence and incidence every three years. This fact sheet cites estimates for the year 2008. These are available at: www.phac-aspc.gc.ca/aids-sida/publication/index-eng.php

Acknowledgements

We would like to thank the Surveillance and Risk Assessment Division of the Centre for Communicable Diseases and Infection Control, Public Health Agency of Canada and Robert Remis, MDCM, MPH, Dalla Lana School of Public Health, University of Toronto for their helpful comments.

References

Tjepkema M. Health care use among gay, lesbian and bisexual Canadians. Health Reports, Volume 19, No. 1; 2008. Statistics Canada. Catalogue No. 82-003-X. Available at: www.statcan.gc.ca/pub/82-003-x/82-003-x2008001-eng.pdf [accessed Dec 1, 2010].

Statistics Canada. Profile of Age and Sex for Canada, Provinces, Territories, Census Divisions and Census Subdivisions, 2006 Census. 2006. Available at: www12.statcan.gc.ca/census-recensement/2006

Public and Population Health Observatory Vancouver Island Health Authority. M-Track Victoria: Monitoring trends in the prevalence of HIV, viral hepatitis, other sexually transmitted infections, and associated risk behaviours among gay, bisexual, transgendered and other men who have sex with men. Phase I–Final report. May 2008. Available at: www.viha.ca/NR/rdonlyres/FBBE9AFA-313C-46B4-A017-6730FEEA1865/0/MTrack_V... [accessed December 1, 2010].

ManCount: Sizes up the Gap. A sexual health survey of gay men in Vancouver, 2010. Available at: www.mancount.ca/files/ManCount_Report2010.pdf [accessed January, 2011].

Myers T, Remis S, Husbands W, Taleski SJ, Liu J, Allman D and Adam B. Technical report: Lambda survey: M-Track Ontario second generation surveillance. Available at www.lambdasurvey.ca [accessed December 1, 2010].

Argus Survey Summary 2005. Available at www.argusquebec.ca/resultats/SummaryArgus2005.pdf [accessed December 1, 2010].

Public Health Agency of Canada. HIV/AIDS Epi Updates, July 2010, Surveillance and Risk Assessment Division, Centre for Communicable Diseases and Infection Control, Public Health Agency of Canada, 2010.

Westhaver R, Allan R. The Nova Scotia Sex Now Survey 2005: Continuity, change and HIV/AIDS. Available at www.cbrc.net/attachments/135_SexNowSurveyHalifaxReport.pdf [accessed January 11, 2011].

Additional resources

BC Centre for Disease Control
Government of Alberta
Government of Saskatchewan
Government of Manitoba
Ontario HIV Epidemiologic Monitoring Unit
Gouvernement du Québec (in French only)
Government of New Brunswick
Government of Nunavut