AIDS IN CANADA

National HIV Prevalence and Incidence Estimates for 2005

More Canadians are living with HIV infection: an estimated 58,000 at the end of 2005 compared with 50,000 at the end of 2002.  This number will likely increase as new infections continue and survival improves due to new treatments, which will mean increased future care requirements.

An estimated 2,300 to 4,500 new HIV infections occurred in 2005 compared with 2,100 to 4,000 in 2002. However, the increase cannot be stated with certainty because of the level of precision associated with the estimates; a firmer conclusion is that overall incidence is not decreasing.


Prevalent HIV Infections in Canada: More Than a Quarter May Not Be Diagnosed

There were an estimated 58,000 people living with HIV infection (including AIDS) in Canada at the end of 2005.

Of these, approximately 15,800 or 27% are not aware of their infection.

Given the new treatments for HIV, it is more important than ever that all Canadians are able to access HIV testing.

HIV Testing and Infection Reporting in Canada

There were 20,669 AIDS cases reported to the Public Health Agency of Canada (PHAC) between 1979 and December 31, 2006, and 62,561 positive HIV tests reported between 1985 and the end of December 2006.

Nominal, non-nominal, and anonymous HIV tests are available in Canada.

Although anonymous testing may encourage testing, it is not available in all provinces and territories.

HIV infection is notifiable in all provinces and territories as of May 1, 2003.

New Developments:  New issues and developments related to HIV testing and counselling have arisen in recent years. These include rapid testing technologies; provider-initiated testing and counselling; nucleic acid amplification testing; the availability of home testing kits in the United States and United Kingdom; and issues related to human rights.

HIV/AIDS Among Youth in Canada

Youth represent a small proportion of the total number of reported HIV and AIDS cases in Canada.

Individuals between the ages of 10 and 24 account for 3.5% of cumulative AIDS cases. For positive HIV test reports, youth between the ages of 15 and 19 account for
1.5% of all reports. In spite of these low proportions, risk behaviour data on young Canadians show the potential for HIV transmission.

A national study found that approximately 50% to 60% of grade 9 and 11 students think
there is a vaccine available to prevent HIV/AIDS. The same survey found that 36% of grade 11 students think that there is a cure for HIV/AIDS.

Data from targeted studies show that street-involved youth, youth who inject drugs, and young men who have sex with men are particularly vulnerable to HIV.

A wide range of prevention activities needs to be implemented to help minimize the risk of HIV transmission among youth.

As of December 31, 2006, there were 20,669 AIDS cases with information
about age reported to the Public Health Agency of Canada (PHAC). Of these, 729 (3.5%) were among youth aged 10 to 24 years.

HIV/AIDS Among Women in Canada

In Canada, a total of 1,866 AIDS cases and 9,569 positive HIV tests were reported in adult women up to December 31, 2006.

Women represent an increasing proportion of those with positive HIV test reports in Canada and in 2006 accounted for 27.8% of such reports.

Heterosexual contact and injecting drug use are the two main risk factors for HIV infection in women.

HIV/AIDS Among Older Canadians

As of December 31, 2006, 12.2% (2,525) of all reported AIDS cases were persons 50 years of age or older.

The proportion of annual positive HIV test reports among those aged 50 years or older increased from 7.6% for the 1985-1998 period to a high of 13.8% in 2006.

Sexual contact is the major risk factor for HIV infection in older Canadians. In 2006, the MSM category accounted for 35.1% and the heterosexual contact exposure category for 31.6% of positive HIV test reports in those 50 years of age or older.

Men account for most of the reported AIDS cases and positive HIV test reports among older Canadians: 90.3% and 82.4%, respectively.

Perinatal Transmission of HIV

The HIV prevalence rate among pregnant women in Canada between 1994 and 2006 ranged from approximately 2 per 10,000 to 9 per 10,000.

The use of antiretroviral therapy by HIV-positive pregnant women is increasing.

Antiretroviral therapy is effective in reducing the risk of mother-to-child transmission of HIV.

All women should have access to prenatal care that includes an offer of HIV testing.

HIV/AIDS Among Aboriginal Persons in Canada: A Continuing Concern

Aboriginal people remain overrepresented in the HIV/AIDS epidemic in Canada.

Among Aboriginal Canadians, the proportion of new HIV infections in 2005 attributed to IDU (53%) was much higher than among all Canadians (14%).

HIV/AIDS has a significant impact on Aboriginal women. During 1998-2006, women represented 48.1% of all positive HIV test reports among Aboriginal persons as compared with 20.7% of reports among non-Aboriginal persons.

Aboriginal persons with a diagnosis of HIV tend to be younger than non-Aboriginal persons. Almost a third (32.4%) of the positive HIV test reports from Aboriginal persons from 1998 to the end of 2006 were younger than 30 years as compared with 21.0% of this age among infected non-Aboriginal persons.

HIV/AIDS Among MSM (Men who have sex with men) in Canada

In Canada, MSM account for 76.1% of cumulative reported AIDS cases among adult males.

MSM have accounted for 68.1% of positive HIV test reports among adult males since testing began in 1985 to the present.

The estimated number of new HIV infections among MSM in 2005 did not decrease and may have increased slightly compared with 2002.

HIV/AIDS Among People Who Inject Drugs (IDU) in Canada

Injecting drug use accounted for 8.0% of cumulative adult AIDS cases and 17.0% of cumulative adult positive HIV test reports up to December 31, 2006.

The 2005 national HIV estimates indicate that the proportion of new HIV infections attributed to injecting drug use decreased from 19% in 2002 to 14% in 2005.

The estimated number of new HIV infections among IDU in 2005 (350- 650) remains unacceptably high.

An enhanced surveillance system, I-Track, has been under way at sentinel sites across Canada to monitor HIV-associated risk behaviours, and HIV and HCV (Hepatitis C virus) prevalence among IDU.

Risk Behaviours Among People Who Inject Drugs (IDU) in Canada

Available data indicate high levels of risky injecting and sexual behaviours among people who inject drugs (IDU), suggesting that the potential for the transmission of HIV in these populations continues to be significant.

The sharing of needles and other injecting equipment among IDU has shown a decreasing trend across various cities in Canada.

Marked differences in injecting drug use risk behaviour and in HIV prevalence across several cities in Canada reflect the need to increase the geographic coverage of surveillance of risky behaviours among IDU.

HIV/AIDS in Canada Among Persons from Countries where HIV is Endemic

Persons from countries where HIV is endemic are over-represented in the HIV/AIDS epidemic in Canada.

HIV infection in persons belonging to the HIV-endemic exposure subcategory is diagnosed at a younger age than in other heterosexual exposure subcategories. Almost 80% of positive HIV test reports assigned to the HIV-endemic exposure subcategory are for individuals under the age of 40.

HIV/AIDS has a significant impact on women from countries where HIV is endemic. Women represented 54.2% of positive HIV test reports attributed to the HIV endemic exposure category between 1998 and 2006 and 41.8% of AIDS cases during this same time period.

HIV-1 Strain Surveillance in Canada

The Canadian HIV Strain and Drug Resistance Surveillance Program (SDR program) monitors and assesses HIV strains and the transmission of drug resistance among individuals with newly diagnosed but untreated HIV infection in Canada.

Although HIV-1 strain B continues to predominate in Canada (88.4% of samples analysed), a wide variety of non-B strains have also been identified (11.6% of samples analysed).

On the basis of results from the SDR program, the likelihood of a non-B strain infection is greater among individuals of African/Caribbean origin than Caucasians and greater among those whose primary risk exposure is heterosexual sex than among those with male-to-male sex as the primary risk exposure.

HIV strain variation is part of the changing evolution of the HIV epidemic in Canada. It is therefore important to implement the systematic collection and analysis of data related to strain surveillance across the country.

Primary HIV Antiretroviral Drug Resistance in Canada

The Canadian HIV Strain and Drug Resistance Surveillance Program (SDR
program) monitors and assesses HIV strains and the transmission of HIV drug resistance among individuals with newly diagnosed but untreated HIV infection in Canada.

Preliminary observations from the SDR program of HIV drug resistance among treatment-naïve individuals with newly diagnosed HIV infection in Canada (i.e. primary drug resistance) are as follows:

- The overall prevalence of primary
drug resistance to at least one
antiretroviral drug is 9.1%.

- The overall prevalence of multidrug
resistance to two or more
classes of antiretroviral drugs
is 1.1%.

- Primary drug resistance has been
observed in both females and
males, across different age groups,
ethnicities, and exposure categories,
in HIV-1 subtype A, B, C, D and
recombinant subtype infections,
and among recent and established
HIV infections.

The prevalence of primary drug resistance is similar to that observed in other countries where highly active antiretroviral treatment is widely used.

HIV/AIDS in Canadian Prisons

HIV prevalence among offenders in Canadian correctional facilities has remained at about 2% over the last 5 years.

Recent prevalence estimates are as follows: 1.6% (males) and 2.8% (females) in federal prisons;  2.1% (males) and 1.8% (females) in Ontario provincial prisons; and 2.3% (males) and 8.8% (females) in Quebec provincial prisons.

HIV infection in Canadian prisons is strongly associated with a history of injecting drugs: roughly one-third of offenders report a history of injecting drug use, and some continue while incarcerated.

Offender populations report very high-risk sexual practices in the community, which may continue or resume after incarceration.

HIV/AIDS and Associated Co-infections

Because of common routes of transmission, decreased immune function, and increased survival due to highly active antiretroviral therapy, individuals infected with HIV are at risk of becoming co-infected with other diseases, such as hepatitis C and sexually transmitted infections.

A significant proportion of HIVinfected individuals also have hepatitis C virus infection; among HIVinfected individuals with a history of injecting drug use, the prevalence is 50% to 90%.

The presence of a sexually transmitted infection, such as syphilis, gonorrhea, or chlamydia, increases the risk of acquiring HIV through sexual contact.

For HIV-infected individuals, the presence of another sexually transmitted infection increases the infectiousness and risk of HIV transmission.

HIV is the most potent risk factor for progression to active disease among individuals infected with Mycobacterium tuberculosis and, globally, TB is one of the leading causes of death among HIV-positive individuals.

A comprehensive approach to prevention, screening, and treatment has been demonstrated to successfully reduce the co-infection disease burden in HIV-infected
individuals.

ACRONYMS/ABBREVIATIONS
AIDS - acquired immunodeficiency syndrome
HIV - human immunodeficiency virus
IDU - people who inject drugs
MSM - men who have sex with men
NEP - needle exchange program
WHO - World Health Organization

Source:

Public Health Agency of Canada . HIV/AIDS Epi Updates, November 2007, Surveillance
and Risk Assessment Division, Centre for Infectious Disease Prevention and Control,
Public Health Agency of Canada, 2007.

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