About chlamydia

  • Chlamydia is caused by the bacteria Chlamydia trachomatis. 
  • Chlamydia is the most commonly diagnosed bacterial STI in Australia. There were over 100,000 notifications in 2017, most among people aged 15-29.1
  • Untreated chlamydia can cause pelvic inflammatory disease (PID) in people with female reproductive organs and epididymo-orchitis in people with male reproductive organs.
  • Research suggests that genital chlamydia infections can be present for months or years without causing symptoms.2,3
  • Reinfection is common and substantially increases the risk of PID.

Diagnosis and treatment

  • Chlamydia is often asymptomatic and many infections go undiagnosed.4,5
  • Nucleic acid amplification testing is used to diagnose chlamydia. See the Australian STI management guidelines for help with diagnosis and treatment. 
  • Chlamydia is a notifiable condition in Australia, and the state or territorty health department must be notified of a positive case. Click here for more information about notification in your state/territory. 

Follow-up and management

  • Consider testing for other STIs if this did not occur at the initial presentation (see the Australian STI management guidelines for further information).
  • Advise no sexual contact for seven days after treatment is administered, and no sex with partners from the previous six months until they have been tested and treated as appropriate.6
  • Sexual partners from the previous six months should be notified to help prevent reinfection and onward transmission.6 It is the diagnosing clinician’s responsibility to initiate a discussion about partner notification. Click here for further information about partner management. 
  • A test of cure is not routinely recommended, unless the patient is pregnant, or the infection was an anorectal infection treated with azithromycin.6
    A test for reinfection is recommended at three months.6 For further information about organising retesting, click here

For detailed information about chlamydia, including treatment and management:
Australian STI management guidelines: Chlamydia.




  1. The Kirby Institute Annual Surveillance Report 2018, available at:
  2. Fairley CK, Gurrin L, Walker J, Hocking JS. “Doctor, How Long Has My Chlamydia Been There?” Answer: “…. Years”. J Sex Transm Dis. 2007;34(9):727-8.
  3. Australasian Society for HIV Viral Hepatitis and Sexual Health Medicine. Australasian Contact Tracing Guidelines 2016 [updated 2016; cited 2022 16th June]. Available from:
  4. Peipert JF. Genital Chlamydial Infections. N Engl. 2003;349(25):2424-30.
  5. Gray RT, Callander D, Hocking JS, McGregor S, McManus H, Dyda A, et al. Population-level diagnosis and care cascade for chlamydia in Australia. Sex Transm Infect. 2019:sextrans-2018-053801
  6. Australasian Sexual Health Alliance. Australian STI Management Guidelines for use in Primary Care 2018 [updated December 2021; cited 2022 16th June]. Available from:

MoCCA is funded by the National Health and Medical Research Council (APP1150014) and is a collaboration between the University of Melbourne and our project investigators and partner organisations in Victoria, New South Wales and Queensland. Click here for a list of our collaborators.

We acknowledge and pay respect to the Traditional Owners of the lands upon which this research is being conducted.