The trends for sexually transmitted infections (STIs) in Australia
Over the past decade (2014–2024), a significant "two-speed" reality has emerged. While HIV transmissions have reached historic lows—a major public health victory—bacterial infections like syphilis and gonorrhea have surged dramatically. Data from the Kirby Institute (UNSW) and the Australian Institute of Health and Welfare (AIHW) show that the national landscape has shifted toward higher volumes of treatable but increasingly resistant bacterial infections.
1. National Overview: The Decade Trend
Over the last ten years, Australia has seen a stark contrast in transmission rates. While medical intervention has curtailed HIV, a decline in traditional barrier methods has led to a spike elsewhere.
| Infection | 10-Year Trend (Approx.) | 2024 Status |
|---|---|---|
| Syphilis | +100% (Doubled) | Significant surge, particularly in women. |
| Gonorrhea | +100% (Doubled) | High rates in men; rising antibiotic resistance. |
| Chlamydia | Stable but High | Remains the #1 most common STI in Australia. |
| HIV | -27% (Decrease) | Major success due to PrEP and effective treatment. |
2. State-by-State Statistics (2023–2024)
Transmission rates vary significantly across the country. The Northern Territory and Western Australia report the highest per-capita notification rates, largely driven by outbreaks in regional and remote communities.
Infectious Syphilis
Syphilis has been declared a "Communicable Disease Incident of National Significance."
- Highest Rates: Western Australia (242 per 100,000) and Northern Territory (212).
- Mid-Range: Queensland (103) and South Australia (86).
- Trend Note: Queensland has seen a recent 20% increase in syphilis notifications compared to its previous 5-year average.
Gonorrhea
- Northern Territory: Leads the nation with roughly 2,200 notifications per 100,000 people.
- NSW: Recently saw a 20% jump in cases between 2022 and 2023.
- Victoria: Accounts for about 30% of national notifications, centred heavily in Melbourne.
Chlamydia
Chlamydia remains the most widespread STI, with over 100,000 cases annually. Roughly 50% of all diagnoses are among young adults aged 20 to 29.
3. Why the Surge? Key Takeaways
Health experts attribute the rise in bacterial STIs to several evolving factors over the last decade:
- The "Condom Gap": As HIV has become a manageable condition and PrEP (Pre-Exposure Prophylaxis) has become the primary tool for HIV prevention, there has been a noted decline in condom use, which is the only effective barrier against bacterial STIs.
- Congenital Syphilis: A tragic trend is the re-emergence of mother-to-child transmission, which has more than doubled since 2015.
- Antibiotic Resistance: There is rapidly increasing resistance to standard treatments for gonorrhea, particularly in NSW and Queensland, making early detection vital.
Summary of Total Increases
The AIHW noted that notification rates increased significantly even before pandemic disruptions: 95% for infectious Syphilis, 79% for Gonorrhea, and 17% for Chlamydia. This data highlights the urgent need for regular testing and a return to holistic sexual health practices.