Third National Aboriginal and Torres Strait Islander Blood Borne Viruses and Sexually Transmissible Infections Strategy: 2010–2013

1.3.3 Epidemiology of sexually transmissible infections and blood borne viruses

Page last updated: July 2010

Sexually transmissible infections

While chlamydia, gonorrhoea, syphilis and trichomoniasis are curable STIs, they are often asymptomatic in those affected and can lead to serious complications if untreated for long periods2.

The consequences of long-term untreated genital chlamydia infection include adverse pregnancy outcomes such as premature labour and birth, low birth weight, intrauterine growth restriction, postpartum endometritis, and neonatal infections such as infectious conjunctivitis, nasopharyngeal infections and pneumonia.

The consequences of long-term untreated gonorrhoea include disseminated infection and illnesses such as polyarthritis and septicaemia.

The consequences of long-term untreated syphilis can give rise to obstetric complications and congenital disease and, where untreated, can be responsible for neurological and systemic late manifestations.

These infections can create discomfort and shame for affected individuals, their families and communities. They can also play a role in relationship breakdown and cultural dysfunction. Furthermore, untreated STIs have the potential to enhance the sexual transmissibility of HIV infection, which so far has remained a confined epidemic in Aboriginal and Torres Strait Islander communities.

The unacceptably high rates of STIs reported in young people from many Aboriginal and Torres Strait Islander communities is compelling evidence of the need to engage in sexual health literacy and STI prevention education. In 2008, 11% of all chlamydia notifications reported from the Northern Territory, South Australia, Tasmania, Victoria and Western Australia occurred among Aboriginal and Torres Strait Islander peoples, despite representing 2.3% of the total population in these jurisdictions. Similarly 55% of all gonorrhoea notifications in 2008 occurred among Aboriginal and Torres Strait Islander peoples in the Northern Territory, South Australia, Victoria, Queensland and Western Australia. Furthermore, 14 per cent (183 cases) of all infectious syphilis notifications in Australia in 2008 occurred among Aboriginal and Torres Strait Islander peoples compared with 1111 cases among non-indigenous people.

Along with other STIs, Aboriginal and Torres Strait Islander communities may be vulnerable to herpes simplex virus (HSV), particularly HSV-2. A recent national seroprevalence study noted higher rates of HSV-2 among the Aboriginal and Torres Strait Islander population (18%) compared with the non-indigenous population (12%). Indeed, the incidence of HSV-2 in some Aboriginal and Torres Strait Islander communities has been found to be considerably higher. HSV-2 is an important factor for increased potential transmission of HIV.

The age-specific standardised rate of diagnosis of infectious syphilis in 2008 was 34 per 100 000 in the Aboriginal and Torres Strait Islander population, compared with six cases per 100 000 in the non-indigenous population. Syphilis in Aboriginal and Torres Strait Islander peoples is most frequently evidenced in younger people, including women of child-bearing age. Remote and very remote communities continue to experience significantly higher rates of chlamydia, gonorrhoea and infectious syphilis compared with regional and metropolitan communities across Australia.3There are suggestions that trichomoniasis is endemic in some populations and associated with adverse pregnancy outcomes. Hepatitis B remains a significant health burden in Aboriginal and Torres Strait Islander communities.

Top of Page

Blood borne viruses

Between 2004 and 2008, population rates for HIV diagnosis among the Aboriginal and Torres Strait Islander population (3.8 per 100 000) were similar to those in the non-indigenous population (4.8 per 100 000). However, available data suggest that differences exist in the prevailing modes of HIV transmission for newly diagnosed HIV infection between the two populations. Between 2004 and 2008 the most frequently reported mode of transmission among non-indigenous, Australian-born, was sexual contact between men (79%), followed by heterosexual contact (13%). Injecting drug use was the sole exposure among 3% of cases. Over the same time period, the most frequently reported route of HIV transmission among Aboriginal and Torres Strait Islander peoples was sexual contact between men (54%), followed by heterosexual transmission (23%) and injecting drug use (22%).4

It is estimated that between 13 000 and 22 000 Aboriginal and Torres Strait Islander peoples are living with hepatitis C in Australia, representing 4% of all Indigenous Australians, compared with 1% of non-indigenous Australians. In 2008, 11 302 cases of hepatitis C were diagnosed in Australia. Of these, 626 (5.5%) occurred among Aboriginal and Torres Strait Islander peoples and 4115 (36%) among non-indigenous people. Indigenous status was not known in 6561 (58%) of notified cases.5

It should also be noted that injecting drug use is a risk factor for hepatitis B infection, although the route of transmission is not systematically recorded. Of the total newly acquired hepatitis B infections in 2008, 9% occurred among Aboriginal and Torres Strait Islander peoples and 73% among nonindigenous people. The Indigenous status was not known in 9% of cases.

In 2008, the diagnosis rate for newly acquired hepatitis B infection in the Aboriginal and Torres Strait Islander population was between one and five times higher than in the non-indigenous population in New South Wales, the Northern Territory, South Australia, Victoria, Queensland and Western Australia. In the non-indigenous population, the rate of diagnosis of newly acquired hepatitis B infection remained low in all states and territories. In 2008, the rates of diagnosis of newly acquired hepatitis B infection in the Aboriginal and Torres Strait Islander population in the age group 20 to 49 years were 4.73 and 4.5 times that of non-indigenous males and females respectively. In 2007, 2.5% of the Australian population identified as Aboriginal and Torres Strait Islander but accounted for an estimated 16% of the Australian population living with chronic hepatitis B infection. Estimated prevalence of chronic hepatitis B infection in the Aboriginal and Torres Strait Islander population ranged from 2% for urban to 8% for rural. Remote Aboriginal and Torres Strait Islander communities are likely to have even higher prevalence rates. Vaccination is a primary measure to control the transmission of hepatitis B and routine screening of people with chronic hepatitis B should feature in ongoing management.

Top of Page

2Northern Territory Health 2002, ‘Trichomonas vaginalis: Consideration of the issues that underpin testing: Which way to go?’, background paper prepared by the Northern Territory AIDS/STD program, Centre for Disease Control Darwin, March 2002
3National Centre in HIV Epidemiology & Clinical Research 2009, Annual Surveillance Report, University of New South Wales.
4Ibid.
5Ibid.