Select Page

Syphilis

What is it?

Syphilis is a sexually transmissible infection (STI) caused by the bacterium Treponema pallidum. It progresses through primary, secondary, latent, and tertiary stages and can cause severe complications if untreated. Syphilis may also be transmitted during pregnancy, resulting in congenital infection. 

Signs and Symptoms

  • Primary: Painless ulcer (chancre) at the infection site.
  • Secondary: Rash (often on palms/soles), fever, lymphadenopathy, mucosal lesions. 
  • Latent: No symptoms; infection detectable only by blood tests. 
  • Tertiary: Neurological, cardiovascular, or gummatous complications. 
  • Congenital: Stillbirth, neonatal death, or long-term disability (e.g., bone, neurological, sensory impairment). 

Transmission

Spread occurs through vaginal, anal, or oral sex via direct contact with infectious lesions, or from mother to child during pregnancy or birth. Rarely, transmission may occur through blood exposure, though screening practices minimise this risk. 

Those at Risk

Anyone who is sexually active can acquire syphilis. Higher prevalence occurs among men who have sex with men, people with multiple partners, and Aboriginal and Torres Strait Islander communities in remote Australia. In New Zealand, cases are increasing among women of reproductive age, raising congenital syphilis risk. Populations in Pacific Island nations also face elevated risk due to limited healthcare access. 

Prevention

Condoms and dental dams reduce, but do not eliminate, risk. Regular testing in high-risk groups, early antenatal screening, and prompt treatment are essential. Partner notification and treatment, alongside public health and community education initiatives, are critical for reducing transmission. 

Diagnosis

Confirmed by serology using both non-treponemal (e.g., RPR, VDRL) and treponemal tests (e.g., TPPA, EIA). Lesion swabs or dark-field microscopy may be used. Cerebrospinal fluid testing is indicated for suspected neurosyphilis. 

Treatment

Benzathine penicillin G is the first-line treatment for all stages, including congenital syphilis. Alternatives such as doxycycline or ceftriaxone may be used where penicillin is unsuitable, though desensitisation is recommended during pregnancy. Follow-up serology is required to confirm cure and detect reinfection. 

Current Situation in Australia & New Zealand

Australia is experiencing record-high rates, with outbreaks particularly affecting remote Indigenous communities. In 2024, over 5,500 cases were reported, and congenital syphilis deaths have already occurred in 2025. The condition has been declared a communicable disease incident of national significance. In New Zealand, cases are also rising across genders, with increasing congenital notifications prompting strengthened public health responses.  

References