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 68% of newly diagnosed HIV infection in Australia between 2013 and 2017, increasing to 82% of newly acquired infection.[63] The Gay Community Period Surveys found a self-reported HIV prevalence of 8% among men attached to the gay community.[63] Data from sentinel surveillance sites reported HIV incidence of 0.85 per 100 person-years in 2016.[64]
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,[65] which is higher than many other countries. Despite this high testing rate, a quarter of HIV diagnoses in men who have sex with men are diagnosed late (25% in 2017)[63] and 9% of men who have sex with men were estimated to have undiagnosed HIV infection in 2017.[63] Results from the Gay Community Periodic Surveys show that 30% of HIV‑negative gay and bisexual men engaged in anal intercourse (insertive or receptive) with casual partners in the past six months, and also reported not consistently using condoms or biomedical preventions with casual partners of unknown HIV or PrEP status.[65] This proportion has been stable in the last five years. In contrast, the number of men using biomedical prevention strategies, such as PrEP, has increased.
People who inject drugs
Initial concern that transmissions among people who inject drugs would increase dramatically were unfounded,[47] 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%.[48] Receptive syringe sharing is a major risk factor for HIV acquisition, and the Australian Needle and Syringe Program Survey reported a decline in the proportion of respondents reporting this behaviour in the 20 year period 1994 to 2014.[66] More recent results from from the same study indicate that this proportion has remained stable in the last five years and was 24% in 2017.[67] The low rates of HIV transmission and prevalence among people who inject drugs reflect the early and successful implementation of prevention strategies, including needle and syringe programs, which were introduced in Australia in 1987.[51]
Female sex workers
Australia has consistently had extremely low rates of HIV infection in female sex workers,[52] with high condom use,[53] regular testing and other prevention strategies minimising transmission. 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.[54] A more recent analysis supports this ongoing low rate of HIV infection in this population, with an incidence rate of <0.1 reported for each year of the five year period 2013 to 2017.[63]
Heterosexuals
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 25% in the period 2013 to 2017. Of the 1,070 cases of newly diagnosed HIV infection attributed to heterosexual contact between 2013 and 2017, 32% were in people from high prevalence countries (> 1% of population with HIV infection) or with partners from high prevalence countries. The number of new HIV notifications in sub-Saharan African-born populations has been relatively stable in the 10 year period 2008 (15 notifications) to 2017 (11 notifications), compared to a 56% decrease among Asian-born populations.[63] In each of the five years 2013 to 2017, almost half of heterosexual diagnoses were classified as late, with 48% in 2017.[63] In 2013 about 20% (15-25%) of non-men who have sex with men living with HIV infection were estimated to have undiagnosed infection.In the most recent results from The Australian Study of Health and Relationships, inconsistent use of condoms during casual sex in the last 6 months among heterosexuals was reported by 49% of people who had vaginal sex. Over a third (37%) of respondents reported ever having been tested for HIV infection.[58] 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.[59]
Aboriginal and Torres Strait Islander people
Of the 5,118 HIV diagnoses since 2013, 175 were in Aboriginal and Torres Strait Islander people, with the rate of diagnosis of HIV infection in 2017 being higher among Aboriginal and Torres Strait Islander people (4.6 per 100,000) than in Australian born non-Aboriginal and Torres Strait Islander people (2.8 per 100,000).[63] In the five year period 2013-2017, the 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 17%) and injecting drug use (18% versus 3%).[61] Rates of other sexually transmissible infections are much higher in the Aboriginal and Torres Strait Islander population compared to the non-Indigenous population, with Chlamydia infection being three times higher and gonorrhoea seven times higher in 2017.[63] Aboriginal and Torres Strait Islander people remain a key population included in the Australian National HIV Strategy.