Chapter 3: Population-specific HIV/AIDS status report: Women - Status of HIV/AIDS

Chapter 3 - Status of HIV/AIDS among Women in Canada

3.1 Information on Surveillance Data

The purpose of this chapter is to present the most recent data available on HIV infection and AIDS diagnoses among Canadian women.  This chapter provides information on positive HIV test reports, reported AIDS cases, routes of transmission, age, pregnancy and perinatal transmission, HIV/AIDS data on specific population segments of women in Canada, and co-infection with other sexually transmitted and blood-borne infections (STBBI).

PHAC uses various types of epidemiological information, including surveillance data, research data and estimates, to monitor HIV infections and AIDS cases in Canada. There are benefits and limitations to each type of information, but multiple sources are required to create a comprehensive picture of HIV/AIDS in Canada.

Surveillance data are provided to PHAC voluntarily by the provinces and territories and consist of positive HIV test reports and reported AIDS diagnoses.  As HIV and AIDS cases are reportable in all Canadian jurisdictions, PHAC has developed case reporting standards to facilitate data-sharing at the national level. While a minimum amount of information is provided for each case^{Footnote 30}, the amount of supplementary data provided varies by province or territory [1]. Supplementary data may include country of birth, ethnicity and exposure category. Supplementary data on ethnicity are important as they help to identify infection patterns among Aboriginal peoples, people from HIV-endemic countries^{Footnote 31}>, and other ethno-cultural groups. Supplementary data on exposure category are also important as they identify the most likely route by which an individual became infected.

Most reported HIV cases and AIDS diagnoses include one or more risk factors. For the purpose of national reporting, HIV/AIDS cases must be assigned to a single identified exposure category (as presented in Figure 4), according to a hierarchy of risk factors.  Figure 4 lists the first six exposure categories in the hierarchy as follows: 1) Perinatal transmission; 2) MSM-IDU: men who have sex with men and have also injected drugs; 3) MSM: men who have sex with men; 4) IDU: people who use injection drugs; 5) Blood/blood products: recipient of blood or clotting factor; 6) Heterosexual contact (which includes “origin from an HIV-endemic country”, “sexual contact with a person at risk” and “NIR-Het”).  Remaining exposure categories include Occupational exposure, Other, and No identified risk (NIR).

If more than one risk factor is reported, the case will be classified by the exposure category listed first (or highest) in the hierarchy. For example, if a case is received citing risk factors as IDU and heterosexual contact, the case would be attributed to the IDU exposure category for the purpose of national data collection, as IDU is accepted as the higher risk activity [3].

Figure 4: HIV Infection Exposure Categories

Source: [4] p.102

The following three exposure categories, by hierarchy, are not included in the diagram: Occupational exposure, Other, and No identified risk (NIR).

Surveillance data alone do not reflect absolute numbers of HIV infections and AIDS cases in Canada at any given time due to considerations listed above, reporting delays, individuals’ reluctance to report risk factors, and lack of routine testing for HIV in the general Canadian population. Consequently, mathematical modeling is used to estimate this data in Canada. By using statistical formulas, which incorporate secondary sources of data, estimates of the number of new infections (incidence^{Footnote 32}) and the number of people living with HIV infection (prevalence^{Footnote 33}) can be obtained. PHAC is responsible for reporting Canadian estimates of national HIV incidence and prevalence rates to the Joint United Nations Programme on HIV/AIDS (UNAIDS) [5].

All available and pertinent forms of data, including national surveillance data, estimates, and provincial/territorial or local studies, will be used in this chapter to present relevant information on HIV and AIDS among women in Canada.

3.2 HIV Strains

Human Immunodeficiency Virus, commonly known as HIV, is a virus that attacks the immune system and can lead to Acquired Immunodeficiency Syndrome, also known as AIDS.  HIV destroys CD4 blood cells that help the body fight off the disease. 

Two types of HIV, HIV-1 and HIV-2, cause illness in humans. HIV-1 is responsible for the majority of HIV/AIDS cases worldwide. HIV-2 is much rarer, much less lethal, and currently is mostly limited to Western Africa. Different subtypes or “clades” of HIV-1 have been discovered and exist worldwide. The most common strain of HIV in Canada is HIV-1, group M, subtype B, representing 88.3% of infections (Figure 5).

Figure 5: HIV Strains

Legend: Group M=main; Group N=new, non-M, non-O; Group O=outlier, CRFs=circulating recumbent forms i.e.:subtype AB, BD, or AG.

Source [1] p.3

Figure 6: Number and Distribution of HIV-1 Subtype by Sex

The distribution of HIV-1 strains differs between men and women. Figure 6 illustrates the distribution of HIV-1 subtypes by sex.

While the differences in HIV-1 sub-type are not vastly different by sex, data from the HIV-1 strain surveillance reports show that the prevalence of non-B subtypes is somewhat greater among females (22.2%) than among males (8.0%). The heterosexual exposure category is associated with higher proportions of HIV-1 non-B subtypes (due to the HET: HIV-endemic exposure subcategory). Since a greater percentage of females have heterosexual contact as their primary exposure category, this is not surprising [2]. Virus subtypes greatly affect future prevention efforts, such as vaccine and microbicides development, which will likely be strain specific [2].

3.3 Overview of HIV/AIDS among Canadian Women

When positive HIV test reports and AIDS diagnoses first started being reported, the majority of HIV infection cases were attributed to the men who have sex with men (MSM) exposure category. While the greatest proportion of new HIV reports continue to be attributed to MSM, the number of positive test reports attributed to adult women has increased significantly since the beginning of HIV in Canada.

Surveillance data tell us that from 1985 to 2009 a total of 11,403 positive HIV test reports among adults (≥ 15 years of age) with information on gender were attributed to women. This makes up 17.7% of the cumulative national total (n=64,335) of adult cases with known gender. In 2009 alone, 609 HIV-positive test reports were attributed to women, accounting for 25.7% of the national total of positive tests with known gender (n=2,368) for that year.

As shown in Figure 7, the proportion of HIV infection attributed to adult women has remained relatively stable over the last 10 years, accounting for roughly one quarter of annual HIV test reports. Consequently, while the annual number of positive HIV tests among women has fluctuated slightly in recent years, the overall trend illustrates that the number of reported HIV cases among women is not declining.

Figure 7: Number of Positive HIV Test Reports among Adults (≥ 15 yrs of age) with Proportion (%) Attributed to Women, 2000-2009 (N = 23,763)

Source: [6] p.19

Although the number of newly reported AIDS cases has dropped in recent years, the proportion (%) of AIDS cases attributed to women does not mirror this trend. Women accounted for just 11.7% of reported AIDS diagnoses in 2000, to a high of 23.2% in 2008 (Figure 8). Cumulatively, from 1979 to 2009, 2,050 adult women were reported as having AIDS.  This number represents 9.6% of the total number of reported AIDS cases among adults with information on gender in Canada (n=21,433) [6]. 

Figure 8: Number of Reported Adult AIDS Cases (≥ 15 yrs of age) with Proportion (%) Attributed to Women, 2000-2009 (N = 3,571)

Source: [6] p.46

With the increased use of antiretroviral drugs (ARVs) to treat people living with HIV, statistics used to describe AIDS cases are becoming increasingly difficult to interpret. While it appears that the proportion of women represented in AIDS cases in Canada is growing, caution must be used in interpreting these data, as they do not address issues which may leave women vulnerable to AIDS, such as access to treatment or treatment failure.

Estimates of national HIV prevalence suggest that at the end of 2008 there were 14,300 (12,200-16,400) women living with HIV, including AIDS, in Canada. This indicates a 17.2% increase from the estimated 12,200 (10,400-14,000) prevalent HIV infections among women in Canada at the end of 2005 [7].

3.4 Geographic Distribution

Across Canada, women are not uniformly infected with HIV (Figure 9). Ontario has the largest number of women affected by HIV, as determined by cumulative positive HIV test reports, representing 38.5% of the total number of positive test reports for women in Canada. Ontario is followed by Québec (25.3%) and British Columbia (17.0%). As Canada’s three largest cities are based in these provinces (Toronto, Montreal, and Vancouver, respectively), these numbers are not surprising.

While the greatest number of women living with HIV, are located in the above three provinces, women from other areas of Canada are more likely to be affected. Women in Saskatchewan form the largest proportion of cumulative HIV case reports by province, representing 39.6% of all test reports in that province. In other words, the male-to-female ratio for HIV reports is approaching 1:1 in the province of Saskatchewan. Women in Manitoba are the next disproportionately affected, comprising 26.4% of HIV test reports in the province. The combined average of the three territories finds that 25.3% of HIV test reports are among women. Geographically, women are least represented in HIV test reports in the provinces of New Brunswick (13.7%) and Nova Scotia (13.9%). The proportion of HIV tests attributed to women reflects patterns evidenced in exposure category data.  The MSM exposure category is the most commonly reported exposure category in British Columbia and Ontario, while IDU and heterosexual contact are the most commonly reported exposure categories in Saskatchewan, Manitoba, and the Territories.

Figure 9: Distribution of Positive HIV Test Reports Attributed to Sex and Women Only by Province/Territory, Cumulative to December 2009 (N = 65,674)

Source: SRAD, personal communiation (2010)| Legend: M:Men; W:Women; U: unknown

Note: Percentages are based on the total number of cases reported by sex, minus reports for which sex was not reported or was reported as transgender.

3.5 Exposure Categories

As previously discussed, exposure categories are used to identify the most likely route by which transmission of HIV infection occurred. The two most common exposure categories for women are heterosexual transmission and injection drug use (IDU) [6]. Refer to Figure 10.

Figure 10: Proportion of Positive HIV Test Reports among Adult Women (≥ 15 yrs of age) by Exposure Category, 1985-2009 (N = 5,643)

Source: [6] p.25

* Heterosexual contact includes a) Origin from an HIV-endemic country (11.1%), b) Sexual contact with a person at risk (25.3%), and c) No identified risk (NIR) – Heterosexual (17.5%). “Other” includes positive HIV test reports in which the mode of HIV transmission is known but cannot be classified into any of the major exposure categories listed here.

3.5.1 Heterosexual Transmission

Heterosexual transmission is the most common route of HIV infection in women, representing 53.9% of cumulative HIV infections (with known exposure category) among adult females [6]. Data are collected and collated using the three following subcategories to further specify risks and routes of transmission: origin from an HIV-endemic country (Het-Endemic), sexual contact with a person at risk (Het-risk), or No identified risk - heterosexual (NIR – Het). Data reveal that the most commonly reported heterosexual exposure subcategory among women is sexual contact with a person at risk, accounting for 46.9% between 1985 and 2009.  Refer to Figure 11 for the cumulative distribution by heterosexual exposure subcategories from 1985 to 2009.

Figure 11: Proportion of Positive HIV Test Reports among Adult Women (≥ 15 yrs of age) Attributed to Heterosexual Exposure Categories, 1985-2009 (N = 3,041)

Source: [6] p.25

a) Sexual Contact with a Person at Risk

Women may identify a sexual partner who is HIV positive or who engages in risk behaviour, such as using injection drugs or having sex with men, as their most likely route of transmission. Within the heterosexual exposure category, this ‘Het-risk’ exposure subcategory has frequently accounted for the highest number of HIV case reports among women in Canada. In 2009, sexual contact with a person at risk represented 36.2% of HIV reports in the heterosexual exposure category, and 21.6% of all HIV reports among women with known exposure category [6]. Refer to Figure 12 for proportions of positive HIV test reports attributed to the six most common exposure categories (including subcategories) among women by year.

Figure 12: Proportions (%) of Positive HIV Test Reports Attributed to Select Exposure Categories in Women (≥ 15 yrs of age), by Year

Source: [6] p.25

* “Blood/blood products include collapsed data from 1) recipient of blood or 2) recipient of clotting factor.
** “Other” includes positive HIV test reports in which the mode of HIV transmission is known but cannot be classified into any of the major exposure categories listed here.

b) No Identified Risk – Heterosexual (NIR-HET)

As shown in Figures 11 and 12, No Identified Risk – Heterosexual (NIR-Het) constitutes a predominant risk category for women in Canada. This category captures individuals for whom heterosexual contact is the only risk factor reported and nothing is known about the HIV-related factors associated with the sexual partner or one’s country of origin.  In 2009, this exposure subcategory represented 38.7% of all HIV reports attributed to the heterosexual exposure category among women, and 23.1% of all HIV reports among women with known exposure category [6].

c) Origin from an HIV-Endemic Country

While Canada does test for HIV during the Immigrant Medical Examination (IME), a diagnosis of HIV does not automatically preclude an immigrant from entering Canada [8].  Positive HIV tests from IMEs performed in Canada are reported to the provinces and territories and shared at the national level like all other positive HIV test reporting [6]. Thus, the data presented as “origin from an HIV-endemic country” from Surveillance Reports include a combination of test reports from routine medical testing (i.e., prenatal), IMEs and other sources.  Due to the reporting system, it is not always possible to determine whether infections attributed to the HIV-endemic subcategory actually occurred in another country before the newcomer arrived to Canada, or if the infection occurred post-arrival.

In 2009, the HIV-endemic exposure subcategory represented 5.5% of all HIV reports in adults, 15.0% of reports among women, and 25.1% of reports among women in the heterosexual exposure category [6]. Women who come from countries where HIV is endemic are largely exposed to HIV through heterosexual contact and cumulatively (from 1985-2009) have represented roughly half (51.8%) of the positive HIV test reports attributed to the HIV-endemic exposure subcategory [6]. Since 2004, there have been year-to-year fluctuations in the annual proportion of cases attributed to this subcategory, with a peak of 22.7% in 2006 and a low of 15.0% in 2009. Refer to Figure 13.

Figure 13: Number of Positive HIV Test Reports among Adult Women (≥ 15 yrs of age) and Proportion (%) Attributed to the Het-Endemic Exposure Subcategory, 2004-2009 (N = 3,838)

Source: [6] p.25

In Canada, the vast majority of individuals (95.8%) associated with the HIV-endemic exposure subcategory identify as being of Black ethnicity [6]^{Footnote 34}. As HIV surveillance and research are two of the few disciplines that collect data specifically on people who come from HIV-endemic countries, information on Black Canadians is used – when available – to help situate epidemiologic data in the Canadian context. This will be further explored in Chapter 4.

d) Sex Work

Women involved in sex work are at greater risk of acquiring and/or transmitting HIV. Sex work is not an HIV exposure category that is routinely collected by provinces or territories in Canada.  Consequently, it is not included as an exposure category in national HIV/AIDS surveillance reports.  However, the prevalence of HIV and associated risk factors (such as high-risk injecting behaviours) among women involved in sex work in Canada has been examined in several research studies.

The Vancouver Injection Drug Users Study (VIDUS) reported that in a cohort of young IDUs (≤ 24 years) there was an HIV prevalence rate of 10%. Of the 117 young female injectors, 20 were HIV positive at baseline, suggesting a prevalence rate of 17.1%. HIV-positive female youth were more likely to work in commercial sex trade, to have had more than 20 lifetime partners, and to inject speedballs (i.e., an injection mixture of heroin and cocaine) daily [10].

Another study, The Maka Project, examined HIV prevalence and risk factors among female sex workers in Vancouver using an interview-administered questionnaire.  Baseline HIV prevalence was 26% and HIV infection was associated with early age of sex work initiation (< 18 years), Aboriginal ethnicity, daily cocaine injection, intensive/daily crack smoking, and unprotected sex with an intimate partner [11].

3.5.2 Injection Drug Use

Injection drug use is the second most reported HIV exposure category among women in Canada. Where exposure category information was reported, the proportion of positive HIV test reports in adult women who inject drugs was 32.8% in 2004.  This proportion increased to 38.5% in 2005 before decreasing again to 33.7% in 2008 [6]. In 2009, the IDU exposure category accounted for 35.4% of HIV case reports among women. 

People who use injection drugs also have an increased risk of contracting the hepatitis C virus (HCV), as the sharing of used needles and injection equipment provides the route of transmission for both HIV and HCV infections. As a result, HCV infection can be used as a marker to indicate risk behaviour among IDU.  Many studies on people who use injection drugs collect epidemiologic data for both.

PHAC’s national enhanced surveillance system, I-Track, which monitors HIV risk behaviours among people who use injection drugs in Canada, has been in place in sentinel sites since 2002.  Using interview-administered surveys and blood or oral fluid samples, researchers collect information regarding drug use, injecting and sexual practices, HIV and HCV testing patterns, and the prevalence of HIV and HCV^{Footnote 35}.

Results from Phase 1 I-Track (2003-2005) revealed 12.2% of female participants to be HIV positive, as compared with 16.3% of male participants.  Moreover, 11.1% of female participants were both HIV and HCV positive, as compared with 14.9% of males who were co-infected [12].  Data also showed HIV/HCV co-infection to be more than two times higher among female participants who self-identified as Aboriginal (First Nations, Inuit or Métis), as compared to  HIV/HCV co-infection prevalence among female non-Aboriginal participants (17.1% vs. 7.4%, respectively) [12].

Similarly, results from Phase 2 I-Track (2005-2008) revealed that 11.4% of female participants to be HIV positive, as compared with 13.9% of male participants.  Moreover, 9.9% of female participants were both HIV and HCV positive as compared with 12.0% of males who were co-infected [12].  Data also showed HIV/HCV co-infection to be higher among female participants who self-identified as Aboriginal (First Nations, Inuit or Métis) as compared to HIV/HCV co-infection prevalence among female non-Aboriginal participants (12.3% vs. 8.5%, respectively) [13].

3.6 Age

HIV affects women of all ages. Cumulative surveillance data from 1985 to 2009 show that the largest proportion of HIV positive test reports – 37.6% of the total number of adult women cases (n=11,403) – occurred in women aged 30-39 years (where age group was reported) [6]. Women aged 20-29 represented the second greatest proportion of HIV positive test reports at 32.5% (Figure 14) [6]. While these data are useful, it is important to keep in mind that the latent nature of HIV infection can delay testing, and age at time of diagnosis is not necessarily an indicator of when the virus was contracted.

Women tend to be diagnosed with HIV at an earlier age than men. Figure 14 presents the cumulative proportions of positive HIV test reports stratified by sex. A greater proportion of positive HIV test reports in women than men are found among the 15-19 year and 20-29 year age categories [6]. There are many reasons to explain this trend. Some argue women access health services more often than men (e.g., for sexual health services or prenatal care) so their likelihood of testing positive at a younger age is greater.  Others maintain that this trend is a result of women’s increased vulnerability to HIV as a result of age-related power differentials in sexual relationships or gender-power dynamics in injection drug use (i.e., women are more likely to requiring help injecting) [14;15]. These vulnerabilities are explored in Chapter 4.

Figure 14: Proportion (%) of HIV Positive Test Reports Attributed to Men and Women by Age Category, 1985-2009

Source: [6] pp.21-22

As the majority of women living with HIV in Canada are of reproductive age, it is important to consider women’s desire to have children and related fertility issues, mother-to-child transmission (MTCT), and post-pregnancy vertical transmission risks (e.g., risks related to breastfeeding).

3.7 Perinatal Transmission

HIV may be transmitted vertically from mother-to-child during pregnancy, childbirth, or breastfeeding. Since 1994, advances in testing and treatment technology have shown marked declines in the rates of MTCT [16].  In 2009, for example, 3 out of 177 exposed infants (1.7%) were confirmed HIV infected [16].

Data on perinatal transmission rates for Canada are available but do not necessarily give us a clear picture of the situation. The numbers reported to PHAC reflect only those infants who were perinatally exposed to HIV and are currently receiving care [6]. As not all women are aware of their HIV infection, test for HIV infection during pregnancy, or know how HIV presents in young infants, cases may go unreported.  Surveillance data do tell us that since 2000, there were between 140 and 240 Canadian perinatally HIV-exposed infants annually. In 2009, 177 HIV-exposed infants were reported; however, not all of these infants later tested positive for HIV. Of the 15 infants born without the use of antiretroviral (ART) prophylaxis in 2009, 1 was confirmed HIV positive. Of the 162 perinatally HIV-exposed infants born with the use of ART prophylaxis that same year, 2 were confirmed HIV positive [6]. According to surveillance data, while the number of infants exposed to HIV has increased over time, the proportion of infants confirmed to be HIV-infected has decreased from 10.7% in 2001 to 1.7% in 2009 [6].

Provinces and territories have developed strategies around pregnancy and HIV testing to reduce the risks of MTCT in Canada. All routine prenatal care in Canada employs one of two HIV testing approaches.  The “opt-in” approach involves pre- and post-test counselling and a mandatory offer of HIV testing that a woman can choose to accept or reject.  The “opt-out” approach includes HIV testing as a standard prenatal procedure, unless a woman specifically declines the test [16].  Currently, fives provinces/territories use the opt-in approach (British Columbia, Yukon, Ontario, Québec, Nova Scotia), while the remainder use the opt-out approach. 

Reference: SRAD, Epi Updates 2010

As shown in Figure 15, both opt-in and opt-out approaches result in high HIV test rates for pregnant women (note that data are only available for select regions).  Further, HIV prevalence among pregnant women who receive prenatal care and who are tested for HIV is low (less than 1%).  However, these data do not capture women who do not receive prenatal care and go untested.  This is of concern because this group of women may be the same group who are at greatest risk of HIV infection.

It should be noted that the Canadian Medical Association [17], along with the Society for Obstetricians and Gynecologists of Canada, the College of Family Physicians of Canada and the Canadian Paediatric Society [18], have endorsed the routine offering of HIV testing to pregnant women unless an individual actively opts-out.

3.8 HIV/AIDS in Diverse Female Populations in Canada

Studies have shown that women who are subject to compound discrimination^{Footnote 36}, such as women from certain ethnocultural groups, women who use injection drugs, and women in prison, are at increased risk of HIV/AIDS [19-24]. Current data describing HIV infections and AIDS cases among certain populations of women are presented in this chapter (Chapter 4 takes a closer look at the reasons why certain populations of women have an increased likelihood of HIV infection).

3.8.1 Aboriginal Women

As previously discussed, women have consistently comprised between 23% and 28% of the proportion of positive HIV test reports over the last 10 years. However, among Aboriginal peoples, women make up a substantially larger proportion. HIV surveillance data indicate that of the positive HIV test reports with Aboriginal ethnicity reported, women and men are almost equally represented. The average proportion of women among positive HIV test reports in Aboriginal persons was 48.6% during the time period 1998 to 2009 (Figure 16). For non-Aboriginal test reports, the corresponding proportion was 20.4%.

Figure 16: Proportion (%) of Positive HIV Test Reports by Sex and Aboriginal / Non-Aboriginal Ethnicity, 1998-2009

Source: [6]

The proportion of reported AIDS cases among Aboriginal peoples attributed to women was 29.5% from 1979 to 2009, reaching a peak of 50.0% in 2008. Non-Aboriginal women made up 14.3% of AIDS cases for the same time period^{Footnote 37}. Refer to Figure 17 for a breakdown of AIDS cases in First Nations, Inuit and Métis women.

Figure 17: Distribution of Reported AIDS Cases, 1979-2009 in Women Who Self-Identified as First Nations, Inuit, Métis or Unspecified Aboriginal Heritage (N = 208)

Source: [6]

As referenced in Figure 18, between 1998 and 2009 the main exposure category for HIV in Aboriginal women was IDU, representing 66.3% of total positive HIV test reports. The second most common exposure category was heterosexual contact, representing 32.4% of all reports. Recipient of blood or blood products, “Other” categories accounted for few of all the total reported positive HIV tests among Aboriginal women [6].

Figure 18: Distribution of Exposure Categories among Positive HIV Test Reports of Aboriginal Women 1998-2009 (N = 1,044)

Source: [6]

Of the total number of perinatally HIV-exposed infants from 1984 to 2009 with reported ethnicity data (n=3,053), 16.2% were Aboriginal. This number is disproportionately high as Aboriginal peoples make up approximately 3.8% of the population of Canada [25]. A three-year study conducted in Vancouver suggested that Aboriginal women were seven times more likely to be HIV positive than their non-Aboriginal counterparts [26]. Of those Aboriginal infants exposed from 1984 to 2009, 10.4% have been confirmed HIV positive [6].

It should be noted there are some limitations with ethnicity reporting at the national level. Specifically, Canada’s two largest provinces, Ontario and Québec, do not provide information on ethnic origin to PHAC when reporting data. This hinders Aboriginal-centred national policy, prevention, and program planning, as the two provinces account for over two thirds of all positive HIV test reports in Canada and includes three large urban centres (Toronto, Montreal and Ottawa) with large multicultural and off-reserve Aboriginal populations [6]. However, Québec’s provincial surveillance report does include data which show that Aboriginal women make up 2.7% of new diagnoses in women in Québec, the majority of which (1.8%) are First Nations women [27].

3.8.2 Women in prison^{Footnote 38}

The population of women in prison in Canada is not static. Constant movement of women in and out of the prison system makes it difficult to track epidemiologic data. However, available data indicate that HIV and HCV rates are higher in prisons than in the general population [4].

The 2007 National Inmate Infectious Diseases and Risk-Behaviours Survey conducted by Correctional Service of Canada (CSC) puts women’s self-reported HIV rate at 7.9%.  The self-reported HIV prevalence rate for men in prison during the same period was 4.5% [28].  A closer examination of data on women in prison reveals that Aboriginal women in prison reported the highest rates of HIV infection (11.7%) [28].

CSC surveillance from 2002-2004 for new admissions to federal prison who took part in voluntary testing indicates that although the estimated HIV prevalence among women fell from 5.0% in 2000 to 3.4% in 2004, women continued to have a higher rate compared to men.  Further, the same report identified Québec and the Pacific Region as having the highest regional prevalence among women in federal prison [29].

The following studies also provide information on HIV infection rates in federal and provincial or territorial penitentiaries:

• In a study of Ontario remand facilities in 2007, women were found to have an HIV prevalence rate of 1.8%, an HCV prevalence rate of 30.2%, and an HIV/HCV co-infection rate of 1.5% [30].
• Results from a Québec study reveal that women in federal penitentiaries had an HIV prevalence rate of 4.7% as compared to 1.7% for men [31].
• In 2007, a study conducted in Québec provincial prisons identified HIV prevalence in women to be significantly higher than in men, at 8.8% compared to 2.4%. HCV infection was 18.5% in women [32]. 
• A survey of women at the Burnaby Correctional Centre for Women in British Columbia had a self-reported HIV prevalence rate of 7.7%. The self-reported HCV prevalence rate was 51.9% [33].

3.8.3 Transwomen^{Footnote 39}

Limited data indicate that transwomen have particularly high HIV prevalence rates.  While no Canadian-specific data were found, a recent meta-analysis estimated an HIV prevalence rate of 27.7% for male-to-female transgender persons (MTF) in North America [34].  Other studies show that transgender persons living in specific regions in Canada, specifically Vancouver (DTES) and Montreal, have a higher prevalence of HIV infection [35].  Further, certain groups of transgender persons have higher HIV prevalence rates than others.  These groups include transgender persons who are also ethnic minorities, sex workers and people who use injection drugs [35].

However, it is difficult to track epidemiological data on this population since MTF HIV test reports are likely included among women’s responses given that transwomen identify and live as women. 

3.8.4 Women who Have Sex with Women ^{Footnote 40}

A growing body of evidence shows that women who have sex with women (WSW) are at increased risk of HIV [36-40]. While sexual transmission of HIV between two female partners is theoretically possible (HIV has been isolated in vaginal secretions, menstrual blood, and cervical biopsies), as of 2005 the Centers for Disease Control and Prevention (CDC) in the U.S. had reported no such confirmed cases ^{Footnote 41}.

British Columbia includes WSW as an exposure category for HIV transmission and reported a total of 21 positive HIV test reports among this population between 1985 and 2007 [41]. While this province routinely collects information on WSW on HIV test reports, neither these data nor supplementary data (i.e., other potential risk behaviours / exposure categories) are reported to PHAC.  More national data are required to identify trends and vulnerabilities in this female population.

3.9 Co-infections with HIV

Other sexually transmitted and blood-borne infections (STBBIs) are often concomitant with HIV as these diseases share common transmission routes, and populations affected by these diseases share common vulnerabilities and common risk behaviours [42;43].  Co-infections also impact on treatment, health management options, and eventual health outcomes.  For instance, women who are co-infected with HIV and another STBBI may experience altered clinical outcomes or accelerated disease progression.

3.9.1 Tuberculosis

Tuberculosis (TB) is a bacterial infection that, if active, generally displays symptoms in the chest and lungs (pulmonary) and can extend to the lymph nodes, organs or brain of the host. HIV weakens the immune system resulting in increased chances of active TB if exposed to the TB-causing microbe [43]. It is reported that adults with latent TB infection have approximately a 10% chance of developing active TB disease in their lifetime [43]. In addition, if exposed, people living with HIV (PHAs) have a higher risk of contracting TB. 

The World Health Organization (WHO) has estimated HIV prevalence in incident TB cases in 2007 to be 5.7% [43].  Also, an estimated 2% to 6% of PHAs have active TB [44].  Rates reveal that the populations vulnerable to TB infection overlap with those vulnerable to the HIV infection, including people who come from countries with higher rates of TB and HIV, Aboriginal peoples, homeless people and people in prisons [44].  

In relation to gender, Canadian surveillance data reflect the following results [45]:

• Women represent 44.1% (N=683) of total TB cases (N=1547) in Canada
• Foreign-born females represent 77.6% (N=510) of total female TB cases
• For known HIV status, 2.5% (N=17) of females with TB are infected with HIV
• For known HIV status, 2% (N=10) of foreign-born women with TB are infected with HIV

Although these data offer some indication of TB/HIV co-infection among women in Canada, they fail to depict the “true picture” of co-infection among this population as 77.6% (N=530) of female TB cases fall under the category “unknown HIV status.” This, therefore, leads to an underestimation of HIV prevalence in women also infected with TB in Canada. 

3.9.2 Sexually Transmitted Infections

Studies have shown that women are more susceptible to being infected with a sexually transmitted infection (STI) than men and that the presence of a STI can increase the risk of contracting HIV.  The likelihood of being infected may be explained in part by female hormonal factors which may alter the thickness of the cervical lining, making women more susceptible to STIs than men [46].  For example, women are four times more likely to get HSV-2 (Herpes simplex virus 2) than men, and, depending on outbreak frequency and severity, being infected with HSV-2 is shown to increase susceptibility to HIV by two to eight times [47].

Chlamydia is the most common notifiable disease and STI in Canada. In 2008, females accounted for over two thirds (N=54,967) of the 82,919 chlamydia cases reported in Canada [48;49].  Young women are disproportionately affected by chlamydia. Between 1999 and 2008, the greatest absolute increase in reported rates of chlamydia infections was seen in 20- to 24-year-old females from 1064.6 to 1824.3 per 100,000 [48;49].

Chlamydia infections are increasing in Canada.  This indicates that unprotected sex in young women is on the rise and unprotected sex places women at increased risk of HIV and other STI transmission. Complications from untreated infection can include pelvic inflammatory disease, which can lead to chronic pelvic pain, ectopic pregnancy and infertility; and transmission from pregnant women to infants during childbirth, resulting in neonatal conjunctivitis or pneumonia. Complications can also include increased HIV acquisition due to inflammation in the genital tract, which increases susceptibility to HIV; and increased HIV transmission as a result of increased shedding of HIV-infected cells [50]. 

Although data show that men are more affected by gonorrhea and syphilis in Canada, like chlamydia, the number of reported gonorrhea and syphilis infections in females has been on the rise since the late 1990s [50].

The Enhanced Street Youth Surveillance System (E-SYS) for street-youth aged 15 to 24 years, reported a prevalence rate for HIV of 1.2%, Chlamydia of 11.3%, Gonorrhea of 2.4%, Syphilis of 0.7% and an HSV-2 of 24.5% among female youth in 2005 [51]:

While not a notifiable disease in Canada, the Human Papilloma Virus (HPV) is described as the most common STI [51].  HPV is known to increase the risk of HIV infection, and, for those who are co-infected, HIV increases the progression of HPV to cervical cancer [51]. While there is a lack of published general population studies in Canada on HPV, data reveal that the prevalence rate of HPV in any given population in Canada is between 10.8% and 29.0% [51]. All published epidemiological studies in Canada have been conducted on women displaying varied prevalence rates by age, ethnicity and place of residence. The National Advisory Committee on Immunization (NACI) recommends HPV vaccination of HIV-positive individuals. NACI also cautions that immune response to the vaccine might be less than that of HIV-negative individuals since the immune response and efficacy in seropositive individuals are unknown [52].

3.9.3 Hepatitis B and Hepatitis C

As hepatitis B virus (HBV) and hepatitis C virus (HCV) are blood-borne, they share similar routes of transmission as HIV. For HBV, high-risk activities can include sharing of injection drug equipment or having unprotected sex with multiple partners. Data on HIV/HBV co-infection are limited; however, since the advent of an HBV vaccine, reported rates of HBV infection have been declining. Overall, the national reported rates of HBV significantly declined from 10.8 per 100,000 population (95% CI 6.0-18.1) in 1990, to 3.3 per 100,000 (95% CI 1.6-4.8) in 2007. The greatest declines have occurred among the cohort of children to whom the recommendations for routine HBV vaccination have applied [53]. However, throughout this time period, the reported HBV rates have been twice as high among men as among women [53]. The E-SYS data suggest that overall, 65.2% of the participating street youth were age-eligible for the school-based HBV immunization program.  Among these youth, only 63.8% were vaccinated against HBV [54]. 

Women who come from countries where HBV is endemicFootnote 42 are also considered at risk for infection or co-infection with HIV; however, data are limited for this subpopulation. As referenced in Section 3.5.2, women who use injection drugs are particularly vulnerable to HIV/HCV co-infection. The use of contaminated needles for tattooing can also increase the risk to contract both HBV and HCV, further placing women at risk.

The I-Track Survey (Phase-2, surveys conducted in 2005-2008) offers the following HIV prevalence and HCV positivity rates among participants who use injection drugs [12]:

• 9.9% of female participants tested positive in HIV/HCV antibody (compared with 12% of male participants); and
• 12.3% of Aboriginal female participants tested positive in HIV/HCV antibody (compared with 8.5% of their non-Aboriginal counterparts).

Results from the Enhanced Street Youth Surveillance (E-SYS) suggest among survey participants who are HIV positive, 37.1% are co-infected with HCV. Among HCV-positive participants, 6.5% were HIV co-infected [51].

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