Australia's STI crisis deepens with syphilis surging among women, First Nations hit hardest

Australia's sexual health landscape is deteriorating in ways that demand urgent attention. New data from the Kirby Institute at UNSW Sydney paint a picture of persistent crisis: in 2025 alone, doctors diagnosed 5,986 cases of syphilis, 42,393 cases of gonorrhea, and 94,184 cases of chlamydia. The first two infections have surged more than 50 percent over the past decade. Chlamydia, while stable in recent years, remains the most frequently reported sexually transmitted infection in the country. The numbers are not abstract. Untreated STIs can destroy fertility, trigger pelvic inflammatory disease, and in pregnancy, cause miscarriage, stillbirth, or birth defects that alter a child's entire life.

The crisis is sharpest among First Nations Australians, who experience infection rates that dwarf those of non-Indigenous populations. They are diagnosed with chlamydia at 2.5 times the rate, gonorrhea at four times the rate, and syphilis at six times the rate. These disparities are not narrowing. Robert Monaghan, manager of the Yandamanjang First Nations Health Research Program at the Kirby Institute, frames the gap plainly: "These are not simply statistics. They reflect ongoing inequities in access to culturally safe, trusted and appropriate sexual health services." The solution, he argues, is not complicated in theory—it requires sustained investment in services designed with communities, not imposed upon them. Point-of-care testing programs launched in 2013 have already demonstrated what's possible: modeling suggests they can more than double the proportion of people treated and cured within two days, and in communities where the program operates, they have reduced both pelvic inflammatory disease and preterm births among First Nations women.

Syphilis is surging among women at an alarming rate. While men account for 78 percent of syphilis diagnoses nationally, women's infection rates have climbed 167 percent over the past decade compared to a 39 percent increase among men. The danger is not merely to the women themselves—syphilis is curable—but to their unborn children. Untreated maternal syphilis can cause miscarriage, stillbirth, or congenital syphilis, a severe infection transmitted in utero that can cause lifelong disability or death. In 2025, fourteen infants were born with congenital syphilis. Over the past decade, there have been 113 cases, and forty of those infants died. Forty-three percent of the 2025 cases occurred in First Nations infants. The Australian government declared syphilis a communicable disease incident of national significance in 2025. Dr. Skye McGregor, the epidemiologist leading the Kirby Institute's report, emphasizes that every case is preventable: "With timely screening, syphilis can be cured and transmission prevented, so even one case of congenital syphilis is completely avoidable and unacceptable." National guidelines now recommend a minimum of three syphilis tests during pregnancy, a change whose impact on congenital syphilis rates remains to be measured.

Chlamydia presents a different challenge. With 94,184 diagnoses in 2025, it remains the most common STI, and diagnosis rates are similar between men and women, suggesting transmission across broad sexual networks. Roughly half of all chlamydia cases occur in people aged 20 to 29. The infection often produces no symptoms, making regular testing essential for sexually active young adults. Treatment is straightforward and prevents complications and further spread.

There is one bright spot in the data. Among gay and bisexual men, where syphilis and gonorrhea have historically concentrated, recent trends show promise. Over the past three years, infectious syphilis diagnoses declined by 30 percent among HIV-negative gay and bisexual men and 37 percent among those living with HIV. Chlamydia diagnoses fell by 31 and 26 percent respectively in the same groups. Gonorrhea remained stable. Professor Andrew Grulich, head of the HIV Epidemiology and Prevention Program at the Kirby Institute, attributes the decline largely to doxycycline post-exposure prophylaxis—doxy-PEP—an oral antibiotic taken after a potential exposure to prevent syphilis and chlamydia. Its use surged after a 2023 consensus statement endorsed the approach. The longer-term increases in STI diagnoses over two decades likely reflect multiple factors: more comprehensive screening, greater awareness, and the availability of highly effective HIV prevention strategies. But the recent reversals suggest that targeted prevention works. Grulich notes that the same health promotion strategies that drove down HIV transmission among gay and bisexual men could accelerate further declines if doxy-PEP uptake increases, while condoms and regular testing remain critical for gonorrhea prevention.

The data underscore a fundamental truth: sexually transmitted infections remain a public health emergency in Australia, one that demands easy access to testing and treatment, prevention efforts that reach the most affected communities, and sustained investment in culturally safe services. The tools exist. What remains is the will to deploy them equitably.