HIV surveillance in Australia
In Australia human immunodeficiency virus (HIV) epidemiology is monitored through a range of public health surveillance systems including case reporting, behavioural and biological surveys, and clinical data collection.
Case reporting involves reporting of newly diagnosed HIV infection by state and territory health authorities to the Kirby Institute.,  The notification includes a number of demographic and clinical characteristics, including sex, date of birth, date of diagnosis, CD4 T-lymphocyte (CD4) cell count at diagnosis, source of exposure to HIV, and clinical evidence of newly acquired infection. More recently information has also been collected on country of birth, year of arrival in Australia, and language spoken at home. Exposure risk is based on self-reported information, and includes sexual exposure, history of injecting drug use, and the receipt of blood products or tissue. The exposure data are used to classify people into the following exposure categories, using a risk hierarchy: men who have sex with men; men who have sex with men and injecting drug use; injecting drug use; heterosexual contact; haemophilia/coagulation disorder; receipt of blood/tissue; mother with/at risk of HIV infection; and health care setting.
Case-reporting of HIV infection in
Morbidity associated with HIV infection is also monitored. Acquired immune deficiency syndrome (AIDS) and AIDS-related deaths are notifiable in Australia and information is forwarded to the Kirby Institute for recording in the national HIV surveillance database. If HIV infection is untreated, it usually progresses to AIDS 8 to 10 years after initial diagnosis. In Australia AIDS is defined as a definitive diagnosis of HIV infection and evidence of a defined opportunistic infection or clinical condition as outlined in Clinical Manifestations of HIV Disease. Due to high treatment coverage in Australia, in recent years the focus has shifted from reporting AIDS and AIDS-related deaths, to monitoring late and advanced diagnoses. A late diagnosis is indicated by a CD4 cell count < 350 cells/µL and suggests HIV infection was acquired around 4-5 years earlier, with a mean decline in CD4 cell count per year of around 50-100 cells/µL. Advanced diagnosis is when the CD4 cell count falls below 200 cells/µL, and the person is vulnerable to opportunistic infections associated with AIDS. Timely diagnosis of HIV infection can reduce an individual’s risk of morbidity and mortality, and has public health benefits by providing opportunities to reduce onward transmission, through mitigation of risk-behaviours or commencing treatment to reduce infectivity.
Routine case reporting is supplemented by enhanced surveillance activities in Australia, including a network of sentinel surveillance sites and biological and behavioural surveys. The network of sentinel surveillance sites (called ACCESS) includes sexual health clinics, primary health care clinics, Aboriginal Medical Services and laboratories and provides information on routine HIV testing and positivity. Repeat surveys provide valuable information on trends over time in risk behaviours and infection. In high-risk populations these surveys include the Gay Community Periodic Survey and the Australian Needle and Syringe Program Survey. Surveys in the general population include the Australian Study of Health and Relationships and the National Survey of Secondary Students and Sexual Health.
History of HIV infection in Australia
The first AIDS diagnosis in Australia was in 1982, and following the introduction of HIV testing in 1985, cases of newly diagnosed HIV peaked at 2,773 in 1987 declining to their lowest level in 1999 (Figure 1). Studies using the back-projection method have estimated that HIV incidence was highest in 1984 (2,890 cases) with a rapid decline in the latter part of the decade. The decline in incidence has been largely attributed to the rapid adoption of HIV prevention practices, including safe sex, and world leading needle and syringe programs.;
Early diagnoses in Australia were characterised by low levels of heterosexual transmission and transmission among people who inject drugs, with most cases diagnosed among men with a history of male-to-male sex (86%). Of the 16,765 newly diagnosed cases of HIV infection between 1984 and 1992, the majority were reported in NSW (67%). The contribution of diagnoses due to receipt of blood, blood products, tissue or treatment of haemophilia declined rapidly from 14% in 1985-1986 to 1% in 1991-1992. There has been an average of one mother-child HIV transmission per year over the last 10 years.
Reflecting the approximately 10-year period from HIV infection to development of AIDS, AIDS diagnoses peaked in Australia at 909 in 1994. The first antiretroviral drugs for HIV infection became available in Australia in 1987 and were initially used as monotherapy then as dual therapy from 1992, leading to a continuing decline in AIDS and AIDS-related deaths. By the end of 2009 there had been 10,446 diagnoses of AIDS and 6,776 deaths following AIDS.
Since 1999 HIV diagnoses in Australia have increased, likely attributed to increases in risk behaviour and confidence in HIV therapies. In the 7 years from 1999 to 2007, HIV diagnoses in Australia increased by 39%.
Figure 1. Newly diagnosed HIV infection in Australia by year
HIV infection in Australia in the last 5 years
HIV infection in Australia is characterised by a concentrated epidemic, defined as a prevalence of greater than 5% in subpopulations. The prevalence of HIV infection has remained low in the general population, and was estimated to be 0.1% in 2013. This rate is comparable with New Zealand and China, but lower than other countries in the region, including Thailand (0.65%), Cambodia (0.50%) and Papua New Guinea (0.44%). To the end of 2013, a total of 35,287 cases (estimated 32,315 distinct cases) of HIV infection had been diagnosed in Australia (Figure 1), with an estimated 26,800 (24,500 – 30,900) people living with HIV.
Over the last 5 years, the annual number of cases of newly diagnosed HIV infection has increased, reaching similar levels to the peak seen in the early 1990s: (Table 1, Figure 1), with the majority of diagnoses in males (87%). The last 5 years have seen a continued increase in diagnoses from 1,069 in 2009 to 1,236 in 2013. Alongside behaviour changes, the frequency of HIV testing has increased in many settings in the past 5 years, and increased testing can lead to increased diagnoses. The median age of diagnosis for males has remained steady at around 37 years. Women have been diagnosed at a slightly younger age, with a median age at diagnosis of 33 years. Over a third (39%) of diagnoses have been classified as late and 19% as advanced. Of all new diagnoses in the period, 15% (840) were previously diagnosed overseas. There have been very few vertical HIV transmissions from mother to child, with five in the last 5 years (1.8% of perinatal exposures).
Table 1. Characteristics of cases of newly diagnosed HIV infection in Australia by year, 2009-20132
|Year of HIV diagnosis|
|Median age (years)|
|Late and advanced HIV infection status at HIV diagnosis|
|Late HIV diagnosis (%)2||41.1||43.0||36.9||37.2||37.4||39.1|
|Advanced HIV diagnosis (%)2||20.1||21.0||19.8||18.1||18.6||19.45|
|Median CD4+ cell count (cells/µL)||406||400||430||435||432||420|
|State and Territory|
|Australian Capital Territory||12||14||11||17||24||78|
|New South Wales||384||351||391||458||401||1,985|
|HIV exposure category (%)3|
|Men who have sex with men||64.4||66.4||70.7||70.5||66.0||67.0|
|Men who have sex with men and injecting drug use||3.7||2.2||2.9||2.8||3.7||3.1|
|Injecting drug use4||2.4||2.4||1.9||2.3||2.4||2.3|
|Receipt of blood/tissue||0.1||0.0||0.2||0.3||0.4||0.2|
|Mother with/at risk of HIV infection||1.1||0.6||0.9||0.3||0.8||0.7|
1 Not adjusted for multiple reporting.
2 Late HIV diagnosis was defined as newly diagnosed HIV infection with a CD4+ cell count of less than 350 cells/µL, and advanced HIV infection as newly diagnosed infection with a CD4+ cell count of less than 200 cells/µL.
3 The “Other/undetermined” exposure category was excluded from the calculation of the percentage of cases attributed to each HIV exposure category.
4 Excludes men who have sex with men
For each year of the last 5 years, the highest number of diagnoses has been reported in the most populous states; New South Wales, followed by Victoria and then Queensland. The rate of HIV diagnosis has remained fairly steady in NSW at 5.41 in 2009 and 5.45 in 2013 (Figure 2). In Queensland and Victoria the rates have increased slightly in the 5-year period from 4.78 to 5.08 and 5.31 to 6.25, respectively. While the Australian Capital Territory and the Northern Territory have had small numbers of diagnoses, rates have increased from 3.23 to 6.06 and 6.74 to 7.51, respectively. While homosexual contact is still the highest proportion of notifications, the proportion of people with heterosexual contact as exposure risk has risen to 27% over the last 5 years. The key populations in the Australian HIV epidemic are discussed in more detail below.
Key populations in the Australian epidemic
Men who have sex with men
Australia’s epidemic has been characterised by transmission among men who have sex with men. Sexual transmission between men accounted for 67% of newly diagnosed HIV infection in Australia between 2009 and 2013, increasing to 88% of newly acquired infection. The Gay Community Period Surveys found a self-reported HIV positivity of 13% among men attached to the gay community. A community-based cohort study of homosexual mean, conducted between 2002 and 2006, found an HIV incidence of around 1% each year, with further data from sentinel surveillance sites reporting positivity of between 1.2-1.6%, which is similar to other European countries and the USA.
The Gay Community Period Surveys shows that each year, about 60% of gay men report that their last HIV test was in the last year, which is higher than many other countries. Despite this high testing rate, a third of HIV diagnoses in men who have sex with men are diagnosed late (32% in 2013) and 12% of men who have sex with men were estimated to have undiagnosed HIV infection in 2013. Results from the Gay Community Period Surveys also show the proportion of men reporting condomless anal intercourse with casual partners has increased from 29.7% to 36.7% in the 10-year period between 2004 and 2013.
People who inject drugs
Initial concern that transmissions among people who inject drugs would increase dramatically were unfounded, and less than 3% of HIV diagnoses over the last 5 years have been attributed to injecting drug use. Over the last 20 years, HIV prevalence among people who inject drugs has remained very low, at around 1-2%. Recent results from a 20-year analysis of needle and syringe program participants indicate a decline in re-use of needles from 33% in 1997 to 21% in 2014, and in the prevalence of receptive syringe sharing from 31% in 1995 to 16% in 2014. The low rates of HIV transmission and prevalence reflect the successful and early implementation of prevention strategies, including needle and syringe programs, which were introduced in Australia in 1987.
Female sex workers
Australia has consistently had extremely low rates of HIV in female sex workers, with high condom use, regular testing and other prevention strategies which have minimised transmission. The HIV positivity among women self-identifying as female sex workers and attending sexual health clinics was 0.03% in 2010-2011 and 0% in 2012-2013.
Notifications of HIV infection attributed to heterosexual contact have increased in recent years with 11% of notifications reporting heterosexual exposure in the period 1982 to 2004, increasing to 27% in the period 2009 to 2013. Of the 1,417 cases of newly diagnosed HIV infection attributed to heterosexual contact between 2009 and 2013, 56% were in people from high prevalence countries (> 1% of population with the infection) or with partners from high prevalence countries. The number of new HIV diagnoses among females reporting heterosexual contact with a partner from a high prevalence country increased by 40% between 2009 and 2013, and by 58% for males. Compared with the previous 5 years, in the period 2009-2013 the population rate of HIV infection diagnosed in the sub-Saharan African-born and Asian-born populations increased by 66%. The increase in heterosexual transmission has been most pronounced in Western Australia (WA), with an almost four-fold increase between 2001 and 2010 from 17 to 66 cases. Between 2005 and 2012, heterosexual contact was the most commonly reported exposure risk in WA, however in 2013 a history of male-to-male sex was the most common exposure risk (49%). The proportion of cases reporting heterosexual contact and classified as late diagnoses has risen in the last 5 years, from 29% in 2009 to 40% in 2013. In 2013 about 20% (15-25%) of non-men who have sex with men living with HIV infection were estimated to have undiagnosed infection.
Recent results from The Australian Study of Health and Relationships indicate inconsistent use of condoms during casual sex in the last 6 months among heterosexuals, with 49% of people who had vaginal sex reporting inconsistent use.
Over a third (37%) of respondents reported ever having been tested for HIV infection. Surveys among migrants from sub-Saharan Africa and South East Asia report barriers to condom use, including difficulty in bringing up the topic with partners and condoms being unnatural.
Aboriginal and Torres Strait Islander people
Of the 5,757 HIV diagnoses since 2009, 128 were in Aboriginal and Torres Strait Islander people. In 2013, the rate of diagnosis of HIV infection was slightly higher among Aboriginal and Torres Strait Islander people (4.9 per 100,000) than Australian born non-Aboriginal and Torres Strait Islander people (3.9 per 100,000). Reported exposure in Aboriginal and Torres Strait Islander people differed from that of Australian-born non-Indigenous cases, with a higher proportion attributed to heterosexual contact (21% versus 13%) and injecting drug use (13% versus 3%). Rate of sexually transmitted infections are much higher in the Aboriginal and Torres Strait Islander population compared to the non-Indigenous population, with chlamydia three times higher and gonorrhoea 13 to 24 times higher. Aboriginal and Torres Strait Islander people remain a key population included in the Australian National HIV Strategy.
While HIV prevalence in Australia remains very low in the general population, the epidemic is concentrated among men who have sex with men and there are increasing diagnoses associated with heterosexual transmission. Prevalence remains low among people who inject drugs and extremely low among sex workers, in contrast to other areas of the world. Risk of transmission through vertical exposure has remained minimal. The proportion of cases diagnosed late has remained steady in recent years, with the highest proportion among cases of heterosexual transmission.