Chapter 3: Population-specific status report: HIV/AIDS and other sexually transmitted and blood borne infections among youth in Canada – Epidemiology

Chapter 3 – The Epidemiology of HIV and Other Sexually Transmitted and Blood Borne Infections among Youth in Canada

3.1 Introduction and context

This chapter summarizes data on the epidemiology of human immunodeficiency virus (HIV) ^{Footnote i}, acquired immune deficiency syndrome (AIDS) and other sexually transmitted and blood borne infections (STBBIs) among youth in Canada.

The Public Health Agency of Canada (the Agency) gathers data from multiple sources to provide a picture of HIV, AIDS and other STBBIs among people living in Canada, and to describe trends in infection among specific sub-groups of the population. The data help inform efforts to prevent, test and treat these illnesses.

Routine HIV surveillance data describe the number of positive HIV tests reported to provincial and territorial health authorities. In fact, every positive HIV test result obtained by a laboratory or health care provider must be reported to the appropriate health authority in that jurisdiction. These authorities provide the data to the Agency twice a year on a voluntary basis. The routine surveillance data only represent individuals who are tested for and diagnosed with HIV for the first time; follow-up tests among individuals who have previously tested positive are not reported in subsequent surveillance data. The case reports provided to the Agency do not identify individuals; instead, a core set of data accompanies each positive HIV test report, such as age, sex and diagnosis date. Additional information, such as race/ethnicity, country of birth, or modes of HIV transmission known as “exposure categories” may also be included in the case report, but the completeness of such data varies by province and territory.

AIDS refers to the most advanced stage of HIV infection. It is marked by the deterioration of the body’s immune system and inability to fight off infections. Since there is no specific laboratory test for AIDS, cases reported to the Agency as part of routine AIDS surveillance are identified by a positive HIV test report and an AIDS-defining illness such as recurrent bacterial pneumonia or Kaposi’s sarcoma. Unlike HIV, AIDS is only a reportable condition in certain provinces and territories, although physicians are required to report the occurrence of AIDS-defining illnesses. The Agency uses these data on HIV and AIDS to produce annual surveillance reports.

Since routine HIV/AIDS surveillance data are limited to people who have been tested and diagnosed, the Agency also produces national estimates of the total new number of HIV infections in Canada in a given year (known as incidence estimates) and the total number of people living with HIV in Canada (known as prevalence estimates). The estimates are produced using mathematical models based on data from a number of sources. Incidence and prevalence estimates offer a more accurate understanding of trends in HIV infection, since they account for individuals who have been diagnosed as well as those who have not and are therefore unaware of their infection. However, while estimates include information on all Canadians aged 15 and over, no specific analysis of incidence and prevalence among youth is available. Therefore, no estimates are presented in this chapter. 

The Agency also collects routine surveillance data on other STBBIs in Canada. Chlamydia, gonorrhea, hepatitis B (HBV), hepatitis C (HCV), and all forms of syphilis are reportable STBBIs, meaning that every positive test result for these infections obtained by a laboratory or health care provider must be reported to the provincial or territorial health authority. With each positive test report, the provincial and territorial health authorities provide the Agency with a set of core data elements (e.g. age, sex) which it uses to develop annual national surveillance reports. These data only reflect the number of people who have been tested and diagnosed with these infections; there is no mathematical model to indicate the true burden of these infections, as there is with HIV.

Enhanced surveillance data provide more detailed information on factors associated with HIV and other STBBIs. They use surveys to collect behavioural data from vulnerable populations, along with tests for HIV and other STBBIs. Types of behavioural data collected include sexual practices (such as number of partners and condom use), HIV testing behaviours, previous diagnosis with HIV and other STBBIs, substance use (such as injection drug use, sharing of needles, etc.), knowledge about how HIV is transmitted and other determinants of health.  The Agency currently conducts enhanced surveillance surveys on street-involved youth through the Enhanced Street Youth Surveillance system(E-SYS); gay, bisexual and other men who have sex with men through the M-Track surveillance system; and people who inject drugs through the I-Track surveillance system. Two other enhanced surveillance systems have been pilot-tested and are undergoing further development. The concept for the E-Track system, which focuses on people originating from countries where HIV is endemic, was piloted in Quebec in 2008 in collaboration with local researchers.  The A-Track surveillance system focuses on Aboriginal (First Nations, Inuit and Métis) people in Canada, and was piloted in Regina, Saskatchewan in 2011-2012.

3.1.1 Data limitations

While information from routine and enhanced surveillance provides crucial insights into HIV, AIDS and other STBBIs, as well as an understanding of risk factors in key populations, it does have limitations which must be kept in mind when interpreting the data. For example, HIV and STBBIs are under-reported in routine surveillance data because they only represent people who have been tested and diagnosed at the time of reporting. In addition, some STBBIs can be asymptomatic (e.g. chlamydia) and others have symptoms that may not develop immediately (e.g.  hepatitis C), with the result that many people do not get tested and remain undiagnosed. Other limitations can include reporting delays, duplicate reporting and missing information.

Data from enhanced surveillance systems must also be interpreted with caution. The information is gathered through cross-sectional surveys at one specific point in time.  While this method is useful for exploring risk factors associated with infection, it does not allow for analyses of cause and effect or changes in individual risk factors over time.  In addition, cross-sectional surveys use primarily venue-based sampling.  For example, in the M-Track surveillance system participants are recruited through venues such as bars, clubs, festivals or social organizations. While this method of recruitment makes it easier to access hard-to-reach populations, it results in data that may not be representative of the entire target population (e.g. in the case of M-Track, it may not be representative of all gay, bisexual or other men who have sex with men in Canada). Finally, the use of self-report surveys in enhanced surveillance systems may result in the underreporting of some risk behaviours because of social desirability bias (i.e. the desire to “say the right thing” to the person administering the survey).

Despite their limitations, both routine and enhanced surveillance data offer a valuable source of information on HIV and other STBBIs and of risk factors associated with infection. Understanding and identifying trends and risk factors is essential to developing effective strategies to prevent, treat and care for these illnesses.

3.2 National data: reported number of positive HIV test reports

Between 1985, when HIV reporting began, and December 31, 2011, there have been 74,162 positive HIV test reports in Canada. The number of yearly positive reports has remained fairly stable over the decade.  Of the 2,208 HIV cases reported to the Public Health Agency of Canada in 2011, 531 cases (24%) were among youth.^{Footnote ii} The youth category was the third most frequently reported age group in 2011, following adults 30-39 (with 668 cases) and 40-49 years old (with 567 cases).  In total, 26.8% of all cumulative positive HIV test reports have been attributed to youth aged 15-29 years, ranging from a high of 38.6% in 1985 to a low of 20.9% in 2003.  Over the past 10 years, the figures have stabilized (Figure 15).

Figure 15: Proportion (%) of positive HIV test reports* by age group and year of test (n=24,264)^{Footnote 1}

Source: Public Health Agency of Canada, 2012a.

*Among HIV test reports where age was reported.

Enlarge Figure 15

3.2.1  Sex and gender

Since 1985, males have accounted for the vast majority of annual positive HIV test reports among youth aged 15 to 29, although the cases among females rose steadily through the 1990s (Figure 16). Given this trend, it is not surprising that the cumulative number of positive HIV test reports for males 15-29 years old has been consistently higher than it has for females in the same age group. By 2011, a cumulative total of 13,895 positive HIV test reports, where sex and age were reported, were among male youth, accounting for 75.7% of the total number of cases in the youth category. In comparison, by 2011, a cumulative total of 4,461 (24.3%) of positive HIV test reports were among female youth.

Figure 16: Proportion (%) of positive HIV test reports* among youth aged 15-29, by sex, 1985-2011 (n=18,356)^{Footnote 2}

Source: Public Health Agency of Canada, 2012a.

*Among HIV test reports where age and sex were reported.

Enlarge Figure 16

Positive HIV tests among males and females are not evenly distributed across the youth category. From 2002 to 2011, the male-to-female ratio differed between younger and older youth. During this period, females were overrepresented in the younger (15-19) age group, accounting for 56.5% of the total positive HIV tests reported in that category. By comparison, males were overrepresented (66.3%) in the 20-29 year age group (Figure 17).

Figure 17: Proportion (%) of positive HIV test reports* by sex and age sub-group, 2002-2011 (n= 5,406)^{Footnote 3}

Source: Public Health Agency of Canada, 2012a.

*Among HIV test reports where age and sex were reported.

Enlarge Figure 17

These data indicate that in general, females tend to be diagnosed with HIV at a younger age than males.  For example, in 2011 alone, more positive HIV tests among females were attributed to the 15-29 year age group (27.0%), than among males (23.1%). In contrast, a larger proportion of positive HIV tests among males were attributed to the 40-49 year (27.1%) and 50 and older (21.0%) age groups, than among females (21.3% and 14.1% respectively) (Figure 18).

Figure 18: Proportion (%) of positive HIV test reports by sex and age group*, 2011 (n=2,170)^{Footnote 4}

Source: Public Health Agency of Canada, 2012a.

*Among HIV test reports where age and sex were reported.

Enlarge Figure 18

The earlier age of diagnosis among females is also apparent in historical data from 1985 onward. Until the early 1990s, the youth category was the most frequently reported age group among females for all positive HIV test reports. Since then, it has remained fairly stable as the second most reported age category (Figure 19).

Figure 19: Proportion (%) of positive HIV test reports among females by age*, 1985-2011 (n=12,533)^{Footnote 5}

Source: Public Health Agency of Canada, 2012a.

*Among HIV test reports where age and sex were reported.

Enlarge Figure 19

By contrast, for males the youth category was the second most frequently reported age category between 1985 and the mid-1990s, when it ranked third. In recent years, the proportion of cases among males in the 15-29 year age group has risen slightly (Figure 20).

Figure 20: Proportion (%) of positive HIV test reports* among males by age, 1985-2011 (n=55,774)^{Footnote 6}

Source: Public Health Agency of Canada, 2012a.

*Among HIV test reports where age and sex were reported.

Enlarge Figure 20

At the national level, identifying sex and gender on an HIV test report is the responsibility of the health care professional providing the testing. Unfortunately, the case report forms do not include a gender category for individuals who do not identify as male or female. In particular, there is no means to capture data on people who identify as ‘transgender’ (individuals whose gender identity does not match their biological sex at birth) or “gender variant”. These and other issues can lead to a misclassification of sex or gender and to the underrepresentation of transgender individuals in HIV surveillance reports. International research findings suggest that transgender individuals may be disproportionately affected by HIV and other STBBIs but there are no national data in Canada to support this.

3.2.2  Geography

Between 1985 and 2011, more than 91% of positive HIV test reports in the youth category were reported by the four most populous provinces combined, namely Ontario, Quebec, British Columbia and Alberta.  This is not surprising given that these four provinces also make up the largest proportion of the Canadian population. However, when we examine the distribution of positive HIV tests by age in each province in Canada, a different picture emerges. The highest proportion of cases attributed to youth are found in Saskatchewan (36%) and the Atlantic provinces (33.5%), followed closely by Manitoba (32.6%) and Alberta (30.1%) (Figure 21). This suggests that youth are over-represented in the number of positive HIV test reports in these provinces compared to their representation in the overall provincial populations. For example, between 2002 and 2011, although youth aged 15 to 29 represented 34.2% of positive HIV test reports in Saskatchewan, they comprised an average of only 21.5% of the province’s general population.^{Footnote 7}

Figure 21: Distribution of positive HIV test reports among youth aged 15-29 by province or territory, against provincial or territorial totals 1985-2011 (n=74,174)^{Footnote 8}

Source: Public Health Agency of Canada, 2012a.

Enlarge Figure 21

3.2.3 Exposure categories – overview

HIV and AIDS cases are assigned an exposure category based on a hierarchy of risk factors associated with the risk of HIV transmission through a given route. These exposure categories include: men who have sex with men (MSM); injection drug use (IDU); heterosexual contact; and having received blood or blood products. Categories ranked highest in this hierarchy represent a greater risk of HIV transmission through that route. If a case is assigned more than one risk factor, it is classified according to the highest exposure category in the hierarchy. For example, people who inject drugs may also be at risk of HIV infection through heterosexual contact; however IDU is classified as higher risk with greater likelihood of HIV transmission. The only exception to this classification approach is for MSM who have also injected drugs, since Canadian evidence suggests that there is a fairly equivalent transmission risk through both routes. Such cases are classified in the combined exposure category “MSM/IDU”.

Classifying cases in a single category according to the hierarchy has inherent limitations. First, it reduces the complex structural, social, cultural and economic determinants of an individual’s vulnerability to HIV to a single source -- individual behaviour.^{Footnote iii} Second, the exposure category is determined by the answers the individual chooses to provide to questions from a health care provider. Finally, the exposure category approach is limited by missing information.  For example, in 2011, nearly half (49.7%) of all positive HIV test reports sent to the Public Health Agency of Canada did not include exposure category data. Despite these limitations, understanding Canadian population-level patterns in HIV exposure can serve to highlight the risks faced by specific sub-populations, and inform prevention and care programs and policies.

3.2.4 HIV exposure categories in youth

Although fewer HIV positive test reports among youth are missing exposure category data (42.5%) than is the case for all age groups (49.7%), the data described in this section should be interpreted with caution.

The MSM exposure category accounts for the largest proportion of cumulative positive HIV test reports among youth in Canada. Between 1985 and 2011, MSM accounted for more than one-third (35.9%) of positive reports in the 15-19 year age group and more than half (58.8%) in the 20-29 year age group. Over the same period, heterosexual contact and IDU were the second and third most common exposure categories, respectively, reported among these age groups.

Reported patterns of exposure to HIV differ among male and female youth. In 2011, among male youth the MSM exposure category accounted for more than two-thirds (72.1%) of positive HIV test reports while the heterosexual contact category accounted for 17.2%. In contrast, that same year, heterosexual contact was the most frequently reported exposure category among female youth, comprising 54.6% of all reported cases.  This category is further sub-divided among individuals who: were born in a country where HIV is endemic (Het-Endemic); had heterosexual sexual contact with a person who was either HIV-infected or at increased risk of HIV infection (Het-Risk); and for whom nothing is known about their partner’s risk factors (no identified risk, or NIR-Het).  Among female youth in 2011, the Het-Risk category accounted for the most cases in the broader heterosexual exposure category (23.4%), while less than half (40.6%) of positive HIV tests were attributed to the IDU exposure category (Figure 22).

Figure 22: Proportion (%) of positive HIV test reports* among male and female youth aged 15-29 with reported exposure category, 2011 (n=279)^{Footnote 9}

MSM

men who have sex with men

MSM-IDU

men who have sex with men and injection drug use

IDU

injection drug use

Het-Endemic

origin from an HIV-endemic country

Het-Risk

heterosexual contact with a person at risk

NIR-Het

heterosexual sex with no identified risk

Other

other known route of transmission

NIR

no identified risk

Source: Public Health Agency of Canada, 2012a.

*Where sex, age and exposure category were reported.

Enlarge Figure 22

The distribution of exposure categories among males and females has varied over time. For example, data from 2002-2011 suggest an overall increase in positive HIV test reports in the MSM category among male youth (Figure 23). Between 2003 and 2007, the proportion of female cases attributed to IDU rose steadily, to a peak of 50% in 2007 (Figure 24). The proportion of cases among female youth attributed to heterosexual sexual contact peaked in 2003 and it has been the most frequently reported exposure category for much of the last decade.

Figure 23: Proportion (%) of positive HIV test reports* among male youth aged 15-29 with reported exposure category, 2002-2011 (n=2,112)^{Footnote 10}

Source: Public Health Agency of Canada, 2012a.

*Where sex, age and exposure category were reported.

Enlarge Figure 23

Figure 24: Proportion (%) of positive HIV test reports* among female youth aged 15-29 with reported exposure category, 2002-2011 (n=1,050)^{Footnote 11}

Source: Public Health Agency of Canada, 2012a.

*Where sex, age and exposure category were reported.

Enlarge Figure 24

3.2.4.1  Perinatal exposure^{Footnote iv}

The data presented in this section are based on information collected by the Canadian Pediatric AIDS Research Group (CPARG) on all children known to have been exposed to HIV during the perinatal period, from conception through to birth and breastfeeding. Perinatal transmission is also known as vertical, or mother-to-child, transmission. The data is delineated according to: confirmed infected; confirmed not infected; not confirmed; and those lost to follow-up. However, it should be interpreted with caution. It does not present a complete picture of vertical transmission in Canada at any given point, since not all pregnant women are tested or aware of their HIV status. In addition, not all HIV positive children receive a diagnosis as infants, resulting in data reporting delays (e.g. children born to women whose own diagnosis is delayed would not be tested as infants; children born outside Canada may not receive a diagnosis until they’re older, etc.).

The overall number of infants perinatally exposed to HIV has increased in Canada since the start of the HIV epidemic, but the proportion of infants exposed and confirmed to be infected declined from over 20% before 1996, to 1.6% in 2011.^{Footnote 12} Advances in antiretroviral treatment since the mid-1990s have greatly reduced the incidence of vertical transmission, from 20.2% prior to 1996 to 2.9% between 1997 and 2010.^{Footnote 13} Without treatment, it is estimated that 25.0% of pregnant women living with HIV would transmit the virus to their infant during pregnancy or at birth. If a seropositive mother breastfeeds her baby, this risk increases to an estimated 35.0%.^{Footnote 14}

According to CPARG, of the 3,567 infants known to have been perinatally exposed to HIV between 1984 and 2011 in Canada, there were 584 confirmed cases of HIV infection. In 2011 alone, there were only three confirmed cases of infection. Of the 110 infants confirmed infected since 2001, none have died of AIDS-related causes, nine died of causes other than AIDS and 10 were lost to follow-up.^{Footnote 15}

3.2.5 Race/ethnicity and HIV among youth

Information on race and ethnicity for HIV surveillance has been available for some provinces and territories since 1998. This data is not available for Ontario and Quebec, which together comprise approximately 66.4% of all positive HIV test reports in Canada reported through 2011. As the completeness of race/ethnicity information provided to the Public Health Agency of Canada varies by province and territory, these data should be interpreted with caution.

Among jurisdictions that provide such data, there has been an overall decrease in the proportion of positive HIV test reports among youth who identify as white, from 51.0% in 1998 to 34.9% in 2011. Recent years have seen an overall increase in the proportion of positive HIV test reports among youth who identify as Aboriginal, with a peak of 46.5% in 2009. In 2011, the proportion was 34.3% (Figure 25). This is particularly significant given that Aboriginal people as a whole make up only 3.5% of the Canadian population.^{Footnote 16} Together, the White and Aboriginal racial/ethnic categories account for the majority of positive HIV test reports among youth for which there is data on race/ethnicity. 

Figure 25: Proportion (%) of positive HIV test reports* among youth by race/ethnicity, 1998-2011 (n=2,489)^{Footnote 17}

Source: Public Health Agency of Canada, 2012a.

*Where sex, age and race/ethnicity were reported.

Enlarge Figure 25

3.2.6 Sex and race/ethnicity

Within different racial/ethnic categories, male and female youth are not equally affected by HIV. From 1998-2011, the majority of cases among Latin American, Asian, South Asian/West Asian/Arab and White youth were male. In contrast, the majority of cases among Black and Aboriginal youth were female (Figure 26).

Figure 26: Proportion (%) of positive HIV test reports* in youth aged 15-29 by sex and race/ethnicity (n=2,487) 1998-2011^{Footnote 18}

Source: Public Health Agency of Canada, 2012a.

*Where sex, age and race/ethnicity were reported

Enlarge Figure 26

3.2.7 Exposure category and race/ethnicity

In addition to differences in sex among the racial/ethnic categories reported with positive HIV tests, different patterns in exposure category are also observed. From 1998 to 2009, MSM was the most reported exposure category among youth in the Latin American (78.3%), Asian (69.8%) and White (51.0%) racial/ethnic groups. IDU was the most reported exposure category among youth who identified as Aboriginal, accounting for 64.4% of cases. Heterosexual risk was the most reported exposure category among youth who identified as Black, accounting for 89.2 % of cases within this group (Figure 27).

Figure 27: Proportion (%) of positive HIV test reports*, among youth aged 15-29 by race/ethnicity and exposure category, 1998-2011 (n=2,429)^{Footnote 19}

Source: Public Health Agency of Canada, 2012a.

*Where sex, age, exposure category and race/ethnicity were reported

Enlarge Figure 27

3.3 National data: reported number of AIDS cases

Between 1979 and 2011, a total of 3,500 AIDS cases among youth aged 15-29 were reported to the Public Health Agency of Canada, representing 15.6% of the total reported AIDS cases in Canada that included information on age. However, since the introduction of highly active antiretroviral treatment (HAART) in 1996, there has been a dramatic decrease in the annual number of reported AIDS cases (Figure 28). HAART has led to a reduction in the number of cases that progress from HIV to AIDS and to fewer AIDS cases resulting in death. As a result, more people living with HIV are managing it as a complex, chronic condition with increased life expectancy. 

3.3.1 Sex and gender

From 1983 to 1993, males accounted for over 85% of annual AIDS cases among youth. Nevertheless, the difference in the numbers of cases among male and female youth has narrowed significantly over the past two decades, largely due to declining numbers of AIDS cases among males, and has remained relatively stable since 1999 (Figure 28).

Figure 28: Number of AIDS cases* among youth aged 15-29 by year and sex, 1979-2011 (n=3,500)^{Footnote 20}

Source: Public Health Agency of Canada, 2012a.

*Where sex and age were reported.

Enlarge Figure 28

3.3.2 Youth and race/ethnicity

As noted for HIV surveillance, data on race/ethnicity among AIDS cases is not available for all jurisdictions, so findings should be interpreted with caution.  Based on the data available, some important trends are worth noting.  The proportion of AIDS cases among youth who identify as White, while still higher than other groups, has decreased significantly, from 83.5% between 1979 and 1989 to 38.9% between 2001 and 2011 (Figure 29). The proportion of AIDS cases increased most dramatically among youth who identify as Aboriginal, from 2.7% between 1979 and 1989 to 27.8% between 2001 and 2011. The proportion of AIDS cases has also increased among youth who identify as Black, from 11.2% between 1979 and 1989, to 24.2% between 2001 and 2011. 

Figure 29: Proportion of AIDS cases* among youth aged 15-29 by race/ethnicity, 1979-2011 (n=2,583)^{Footnote 21}

Source: Public Health Agency of Canada, 2012a.

*Where age and race/ethnicity were reported.

Enlarge Figure 29

3.4 National data: reported number of positive test reports for select STBBIs

In addition to HIV, other STBBIs among youth continue to be a growing public health concern in Canada. HIV and other STBBIs share routes of transmission (e.g. blood, semen and other bodily fluids), behavioural risk factors (e.g. unprotected sex, sharing contaminated needles and other drug paraphernalia, unsafe tattooing), and social structural risk factors (e.g. poverty, homelessness, mental health). Certain STBBIs also facilitate HIV transmission. HIV and STBBI co-infection can complicate the progression, treatment and management of both. For these reasons, it is important to consider rates of HIV among youth in the context of other STBBIs.

3.4.1 Chlamydia

Chlamydia continues to be the most commonly reported bacterial sexually transmitted infection (STI) in Canada. Since 1997, reported rates of chlamydia have risen steadily in males and females and across all age groups, although young females continue to be disproportionately represented.

In 2010, 94,690 cases of chlamydia were reported to the Public Health Agency of Canada. While the largest proportion of these (62.8%) were among youth aged 15-24, the highest rates of chlamydia relative to the general population were actually among youth aged 20 to 24, (1,470.7 per 100,000 people). In this age group, the rate of chlamydia among females (2,005.5 per 100,000) was more than twice as high as that among males (961.8 per 100,000) (Figure 30). The highest rates of chlamydia were reported in Nunavut, the Northwest Territories and Yukon.^{Footnote 22}

Figure 30: Reported rates (per 100,000 population) of chlamydia by sex and age group, 2010^{Footnote 23}

Source: Public Health Agency of Canada, 2012a.

Enlarge Figure 30

3.4.2 Gonorrhea

Gonorrhea remains the second most commonly reported bacterial STI in Canada. Since 1997, the overall number of reported cases has increased, although this has levelled off in recent years.

In 2010, 11,397 cases of gonorrhea were reported in Canada, of which approximately half (48.7%) occurred among youth aged 15-24. Rates were higher among females than males at younger ages, and higher among males in older age groups. The highest reported rates of gonorrhea infection in females were among those aged 15-19 (147.0 per 100,000 people) and 20-24 years (133.8 per 100,000) (Figure 31). For males, the highest reported rates were among those aged 20-24 (134.5 per 100,000), followed by those aged 25-29 years (109.9 per 100,000 people) (Figure 31).^{Footnote 24}

According to the 2010 data, rates of gonorrhea were not evenly distributed across Canada. The highest rates were reported in the three territories, followed by Manitoba and Saskatchewan.^{Footnote 25}

Figure 31: Reported rates (per 100,000 population) of gonorrhea by sex and age group, 2010^{Footnote 26}

Source: Public Health Agency of Canada, 2012a.

Enlarge Figure 31

3.4.3 Infectious syphilis

In 2010, 1,757 cases of infectious syphilis (including primary, secondary and early latent stages) were reported, equivalent to 5.2 people per 100,000. People aged 25-29 and 30-39 years carried the greatest burden (8.9 per 100,000 and 9.1 per 100,000, respectively). Historically, more cases have been reported among males than females; in 2010, males accounted for 90.5% of all reported cases.

Youth aged 15-24 represent only 14.6% of infectious syphilis cases in Canada, but rates differ between younger and older youth. For those aged 15-19, there were 2.6 infections per 100,000 compared to 8.4 per 100,000 among 20-24 year-olds. Among youth, males continue to be disproportionately affected (Figure 32). 

Figure 32: Reported rates (per 100,000 population) of infectious syphilis by sex and age group, 2010^{Footnote 27}

Source: Public Health Agency of Canada, 2012a.

Enlarge Figure 32

3.4.4 Hepatitis B

In the mid-1990s, the vaccine for hepatitis B (HBV) was approved in Canada for distribution through routine, publicly funded provincial and territorial immunization programs. Since its inclusion in these programs, rates of acute HBV have declined among Canadians in the targeted age groups.

In 2010, 1,884 cases of HBV were reported to the Public Health Agency of Canada, for an overall infection rate of 5.5 per 100,000 people. Youth aged 15-24 made up 8.1% of the total number but rates of infection differed between younger and older youth. Among those aged 15-19, the rate of HBV was 1.8 per 100,000, compared to 4.7 per 100,000 among youth aged 20-24 years (Figure 33).

Figure 33: Reported rates (per 100,000 population) of HBV by sex and age group, 2010

Enlarge Figure 33

3.4.5 Hepatitis C

Reported cases of hepatitis C (HCV) have declined in Canada in recent years. In 2010, there were 10,741 cases of HCV reported to the Public Health Agency of Canada, or a rate of 31.5 per 100,000 people, down from 40.5 per 100,000 in 2005. This represents a decline of 22% during that five-year period. The highest reported infection rate occurred among males 40 to 59 years old (78.2 per 100,000) and among females 25 to 29 years old (34.4 per 100,000).

Youth aged 15-24 accounted for only 7.7% of the total number of HCV infections in Canada in 2010. Rates of HCV were lower for males and females aged 15 to 19 than for those aged 20-24.  However, in both age groups, infection rates were slightly higher for females, at 9.2 and 29.1 per 100,000 for the 15-19 year and 20-24 year age categories respectively, compared to 6.1 and 26.1 per 100,000, respectively, among males in these age groups (Figure 34).

Figure 34: Reported rates (per 100,000 population) of HCV infection by sex and age group, 2010

Enlarge Figure 34

3.5 Results from national enhanced surveillance among key populations

The Public Health Agency of Canada conducts enhanced STBBI surveillance on specific key populations at-risk: the Enhanced Street Youth Surveillance in Canada (E-SYS), the Enhanced Surveillance of HIV Risk Behaviours among People who Inject Drugs in Canada (I-Track), and the Enhanced Surveillance of HIV and Other Sexually Transmitted and Blood Borne Infection and associated risk behaviours among Men who have Sex with Men in Canada (M-Track). Data specific to youth has been extracted from these surveillance systems to describe trends in STBBIs, and risk factors associated with them, among specific sub-groups of youth in Canada.

3.5.1 Enhanced Street Youth Surveillance (E-SYS)

A total of 1,325 street-involved youth, aged 15-24, participated in the E-SYS Cycle 5 cohort. Females made up just over one-third of participants (37.8%) and males nearly two-thirds (62.2%) of participants surveyed in Vancouver, Edmonton, Saskatoon, Toronto, Ottawa, and Halifax.^{Footnote 28} Participants were asked to complete a questionnaire (administered by a nurse) and provide urine and blood samples to test for specific STBBIs. About 96% of participants provided urine samples and 88% provided blood samples.

Among survey participants, 25.4% of those tested had one or more STBBIs (Table 2). The most prevalent were genital herpes (14.9%), chlamydia (10.0%) and hepatitis C (5.2%). Thirteen participants, or 1.2%, tested positive for HIV.^{Footnote 29}

Overall, a larger proportion of females (34.6%) than males (19.9%) tested positive for STBBIs. In particular, 2.2% of females tested positive for gonorrhea and 24.5% for genital herpes compared to males (0.8% and 9.2% respectively). Rates of other STBBIs did not differ between males and females.^{Footnote 30}

In the survey, 34.2% of participants identified as Aboriginal (i.e. First Nations, Métis or Inuit), 52.5% as Caucasian and 13.3% as other ethnicities. A significantly higher proportion of street-involved youth who self-identified as Aboriginal (33.8%) tested positive for an STBBI, compared to 19.7% among Caucasian street-involved youth and 27.2% of participants who identified as other ethnicities.^{Footnote 31}

In particular, the prevalence of chlamydia (14.5%), hepatitis C (8.6%) and genital herpes (19%) was significantly higher among Aboriginal street-involved youth than among youth who identified as Caucasian (7.1%, 4.0% and 12.0% respectively) or an ‘other’ ethnicity (9.5%, 0.7% and 14.7% respectively). 

Source: Public Health Agency of Canada, 2011.

3.5.2 M-Track

As mentioned earlier in this status report, M-Track is an enhanced surveillance system that tracks HIV, STBBIs and associated risk behaviours among MSM through periodic, cross-sectional surveys at selected centres across Canada. Participants are primarily recruited using venue-based sampling methods; participation is voluntary, anonymous and requires informed consent. Information on demographics, sexual behaviours, drug use, HIV and other STBBI testing behaviour, and knowledge of how HIV is transmitted are collected via self-administered questionnaire. A blood specimen is collected from a finger-prick sample to test for HIV, HCV and syphilis.Footnote 33

Between 2005 and 2007, five sentinel sites participated in Phase 1 of M-Track: Montreal, Toronto, Ottawa, Winnipeg and Victoria. Of the 4,838 men who participated in the study, 4,793 completed a questionnaire. The Phase 1 sample comprised 589 youth aged 15-24, representing 13.3% of all participants who provided their age. The majority of youth participants were between 20 and 24 (87%), and the average age was 22.^{Footnote 34}

A substantial proportion of youth self-reported their sexual orientation as gay (71%) and approximately 21% as bisexual. Others identified themselves as straight or “Other” (9%). When asked about their national or cultural ancestry, approximately 7% of youth respondents reported Aboriginal ancestry.^{Footnote 35}

Among youth who provided a biological sample of sufficient quantity for testing and completed a questionnaire, approximately 2% (n=9) tested positive for HIV. Of these, three of the nine youth did not know they were HIV positive.^{Footnote 36} The lifetime prevalence of HCV was approximately 3% compared to less than 1% for syphilis.

3.5.3 I-Track

I-Track is the national enhanced (behavioural and biological) surveillance system that collects information on HIV and HCV risk behaviours among people in 10 sentinel sites across Canada who injects drugs. Using an interviewer-administered questionnaire, information is collected on selected demographic variables, drug use, injecting and sexual behaviours, and testing history for HIV and HCV and knowledge of how HIV is transmitted. A biological sample (finger prick blood sample or oral fluid) is collected for testing.^{Footnote 37}

Of the 3,089 respondents, 343 youth aged 15-24 years old participated in I-Track Phase 2 (2005-2008) in Victoria, Central and North Vancouver Island, Prince George, Edmonton, Regina, Thunder Bay, Sudbury, Toronto, Kingston and the SurvUDI network (Ottawa and eight sites in the province of Quebec). Just over half of the Phase 2 sample were female (51.3%) and one-third self-identified as Aboriginal (First Nations, Métis or Inuit) (31.7%). A higher proportion of female participants self-identified as Aboriginal than male participants (37.5% vs. 25.3%, respectively).^{Footnote 38}

Source: Public Health Agency of Canada, 2010.

Among youth participants who provided a biological sample of sufficient quantity for testing, the prevalence of HIV was 3.0% and the lifetime prevalence of HCV was 37.0%. HIV prevalence was similar between male and female youth (3.1% vs. 3.0%, respectively). Lifetime prevalence of HCV was higher for females than males (41.3% vs. 32.5%, respectively) (Table 3). Among HIV positive youth, 57.1% did not know their positive HIV status. This was true for a higher proportion of males (66.7%) than females (50.0).^{Footnote 40}

3.6 Summary

While the majority of Canadians lead healthy lives free from HIV and other STBBIs, the rates of many STBBIs are increasing.  Among people who do get these infections, youth often make up a disproportionate number of cases. In many instances, certain sub-groups of youth are more vulnerable to infection than others.

Annual rates of HIV diagnoses in Canada have remained relatively stable over the past few years, as have the proportion of youth among those diagnosed.  In 2011, youth aged 15-29 years made up approximately one-quarter of the number of positive HIV test reports in Canada. Males accounted for the majority of youth cases.  In particular, the MSM exposure category accounted for the largest proportion of positive test reports among all youth (even though this category only includes male youth). Other sub-groups may also be more vulnerable to HIV infection, particularly Aboriginal youth.

With the introduction of biomedical interventions such as antiretroviral therapy in 1994 and highly active antiretroviral therapy in 1996, Canadians infected with HIV are living longer lives and managing HIV as a complex, chronic condition. As a result, there has been a decrease in the number of new AIDS diagnoses reported in Canada each year. Youth generally make up a small proportion of these diagnoses, accounting for approximately 16% of the cumulative total number of AIDS cases over the past three decades.

Rates of other STBBIs among youth are particularly worrying.  For example, in 2010, youth comprised about two-thirds of cases of chlamydia and about half the cases of gonorrhea. Females made up a majority of people with these infections.  Left untreated, chlamydia and gonorrhea can have significant consequences for the reproductive health of youth in their adulthood, including infertility and greater risk of ectopic pregnancy.

The risk behaviours that ultimately lead to infection with HIV and other STBBIs are influenced by social, cultural, economic and structural factors that shape an individual’s vulnerability to infection. Chapter 4 discusses how these varied determinants of health affect the vulnerability of youth in particular, and how these may be addressed to create the conditions necessary to support the health and wellbeing of young people.

Endnotes