Sexually Transmissible Infections

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The Australian Blood Borne Viruses and Sexually Transmissible Infections Surveillance Report analyses data on sexually transmissible infections, including chlamydia, gonorrhoea, syphilis, human papillomavirus (HPV) and donovanosis. While simple treatments are available for most of these sexually transmissible infections, left untreated chlamydia and gonorrhoea can cause pelvic inflammatory disease in females and infertility in both males and females, and syphilis can cause serious long–term effects including heart failure, dementia, blindness and brain damage.

In 2015, there were 66,033 notifications for chlamydia, 18,588 notifications for gonorrhoea and 2,736 notifications of infectious syphilis.


You can explore the sexually transmissible infections data from Australia in the interactive graphs below. Click on the tabs above the graph to view notifications by sex, age and state.

Scroll down to read the key findings and to download the full version of the report.

Key Findings


In 2015, there were 66,033 chlamydia notifications.

77% of these notifications were among 15–29 year olds. The rate of notification of chlamydia in the Aboriginal and Torres Strait Islander population in the Northern Territory, Queensland, South Australia, and Western Australia was over three times that in the non–Indigenous population in 2015. 

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The rate of chlamydia notification has increased steadily between 2006 and 2011, but since 2011 has remained relatively stable overall, with the same patterns seen in males and females. 

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Among 15–19 year olds, there has been a decline in the chlamydia notification rate by 19% since 2011.



In 2015 there were an estimated 260,000 new cases of chlamydia cases in 15–29 year olds, of which only 28% were estimated to be diagnosed.  

Chlamydia testing has doubled

From 2008 to 2015, chlamydia testing has doubled  in 15–29 year olds attending general practice, but overall levels remain low.

From 2010 to 2015, the incidence of chlamydia (anorectal) among gay and bisexual men attending sexual health clinics was relatively stable. Over the past 5 years chlamydia incidence has increased in female sex workers by 27%; however chlamydia incidence is lower in female -sex workers than females not engaged in sex work.




There were 18,588 cases of gonorrhoea notified in 2015. 

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Between 2006 and 2015, notification rates for gonorrhoea nearly doubled in both males and females.

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Gonorrhoea notification rates were highest among men aged 25–29 years and 20–24 years.

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Comprehensive STI testing in gay men has increased from 47% in 2011 to 60% in 2015, according to results from the Gay Community Periodic Survey.

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Of the gay and bisexual men attending sexual health clinics, 27% of HIV–positive men had a new gonorrhoea infection detected in rectal swabs in 2015; compared with 11% of HIV–negative men, and in the past five years incidence has increased in both populations. 

In female sex workers attending sexual health clinics, 2.3% had a new gonorrhoea infection detected in 2015, increasing from 0.9% in 2011. Among females not involved in sex work, the incidence of gonorrhoea was similar but stable over time (between 1.2% and 1.6% with new infections in each year).

Infectious syphilis



In 2015, there were 2,736 notifications of infectious syphilis. Infectious syphilis is defined as an infection of less than two years duration.

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The notification rate of infectious syphilis among men has increased in the past ten years, from 6.5 per 100,000 people in 2006 to 21 per 100,000 people in 2015. At 46 per 100,000 people, notification rates were highest among males aged 25–29 years. The rate among women has fluctuated and remained low between 2006–2014, increasing from 1.5 in 2014 to 2.5 per 100,000 people in 2015.



There were four notifications of congenital syphilis in 2015, declining from a high of 11 in 2006.

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Among gay and bisexual men attending sexual health clinics participating in ACCESS, the average number of syphilis tests per man increased from 1.2 in 2011 to 1.5 in 2015.

In 2015, of the gay and bisexual men attending sexual health clinics, 9.7% of HIV–positive men had a new diagnosis of syphilis infection compared with 3.7% of HIV–negative men, and in the past five years incidence increased by 42% in HIV–negative men and 38% in HIV–positive men.

Syphilis incidence in female sex workers was very low

In the past five years (2011­–­2015), syphilis incidence in female sex workers was very low and relatively stable (with 0.2­–­0.4% of women with a new diagnosis of infectious syphilis per year). 


After a decade of steady increases in both testing and diagnoses of chlamydia, there has been a levelling off in the rate of chlamydia diagnoses, and even a decline in the youngest age group. However the vast majority of infections in young people remain undiagnosed and therefore untreated.

Gonorrhoea and syphilis in Australia continue to be infections primarily among men who have sex with men in urban settings, and among young heterosexual Aboriginal and Torres Strait Islander people in remote communities.

Gonorrhoea and syphilis has been diagnosed more frequently in men in the past five years. These increases may be due to increased testing and use of more sensitive gonorrhoea testing technology in some places. The rise may also relate to increases in condom-less sex among men who have sex with men, linked to the greater availability and awareness of highly effective HIV prevention strategies.There has been a rise in chlamydia and gonorrhoea in the past three years among females involved in sex work.

There has also been an increase in gonorrhoea notifications among women in Australia which may be due to the adoption of dual testing in most pathology laboratories in Australia, which means that if either a chlamydia or gonorrhoea test is ordered by a clinician, both are conducted.

Overall, these data emphasise the need for enhanced health promotion and testing and treatment to be routinely offered to sexually active adolescents, young adults, and other priority populations.