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Chlamydia Trachomatis Infections

Queensland Health Guidelines for Public Health Units

Revision History

Version Date Changes
2.0 April 2016 Full revision of guideline. 
1.0 December 2010 Full revision of guideline.

Infectious Agent

The infectious agent is Chlamydia trachomatis, usually serotypes B, D-K for sexually acquired anogenital infections in adults and perinatally transmitted infections of the neonate and infant. Other serotypes are responsible for trachoma (A-C) and lymphogranuloma venereum (L1-3). Chlamydiae are gram negative obligate intracellular bacteria.

Notification and Reporting Criteria

Laboratory notification only. Laboratory reporting to Notifiable Conditions System.
For case definitions see Queensland Notification Criteria: Guidelines for Laboratories (PDF, 320KB)

Public Health Significance and Occurrence

Anogenital Infections

Chlamydia was the most frequently reported notifiable condition in Queensland and Australia in 2015, with prevalence highest in young people and Aboriginal and Torres Strait Islander people. Asymptomatic infection is common in men and women, and annual screening for chlamydia infection in all sexually active people aged 15–29 years is recommended because of increased prevalence and risk of complications. The protective effect of condoms is high. The urethra, pharynx, anus and rectum can be infected in either gender. Anogenital infection increases the risk of acquiring and transmitting HIV infection.

Chlamydia is the most common cause of non-gonococcal urethritis in young males and possible sequelae include epididymitis and reactive arthritis (Reiter's syndrome). Bilateral epididymitis could potentially impair fertility.

In women, untreated infection can lead to salpingitis and pelvic inflammatory disease (PID); with subsequent sequelae of chronic pelvic pain, and sub-fertility and ectopic pregnancy due to tubal obstruction. The risk of PID and related sequelae increases with each subsequent chlamydia infection. Chlamydia is a more common cause of PID than gonorrhoea and is a significant cause of fertility investigation and treatment.

Infection during pregnancy can result in premature rupture of membranes and premature delivery, with attendant morbidity and mortality. Chlamydia can be transmitted to the neonate, usually at delivery, resulting in ocular, upper respiratory tract and/or anogenital infection.

Perinatally acquired chlamydia infections may persist in the nasopharynx, urogenital tract or rectum for more than two years. Differentiating infection acquired at birth from infection related to sexual abuse may be difficult in children aged under three years. To determine whether there may be sexual transmission and hence the possibility of sexual abuse, consultation with sexual health/paediatric/child safety staff may be necessary.  Refer to the reporting a reasonable/reportable suspicion of child abuse and neglect guideline.

Resources, including contact lists and fact sheets for Queensland Health staff are also available via the Queensland Health intranet.  Search for ‘child protection’.

Clinical Features

Anogenital Infections

See Australian STI Management Guidelines for Use in Primary Care and/or Primary Clinical Care Manual. A Doctor’s fact sheet and patient fact sheet are available.

Reiter's Syndrome

Conjunctivitis and reactive arthritis with or without skin manifestations can develop in either gender following anogenital infection. Occasionally anogenital infection can lead to inclusion conjunctivitis due to auto-inoculation or oral sex. Follicular formation may be seen but corneal lesions are rare; infection is usually unilateral with palpebral oedema.

Perinatal Infections

Infected infants may develop conjunctivitis and pneumonitis. Inclusion conjunctivitis develops within 5-12 days of birth in 15-35 per cent of neonates exposed to maternal infection, and is typically unilateral, with purulent discharge and may result in mild scarring if untreated. Infant pneumonia due to chlamydia typically starts at 4 -11 weeks of age with insidious onset, stuffy nose, dyspnoea and a gradually worsening cough, the infant is usually afebrile.

Mode of Transmission

Anogenital infection occurs via contact with infected anogenital secretions/discharge during sexual intercourse or sexual contact such as fingers and sex toys where sexual secretions/fluids are present. There is a 30-50 per cent likelihood of transmission per act of unprotected intercourse. Transmission probability by oral sex is unknown. Women can be infected for years and men can be infected for months. There is limited data on duration of infectiousness over time but contact tracing should occur for the previous six months. About two-thirds of male partners of infected women and female partners of infected men will be infected.

Perinatal transmission can occur at birth.

Investigation and Screening

For screening of asymptomatic individuals see Guidelines for Preventive Activities in General Practice, which recommend annual screening for all sexually active people aged 15–29 years and men who have sex with men, and 3-6 monthly screening in higher risk men who have sex with men. For screening of at risk groups see populations and situations in the Australian STI Management Guidelines.



See Australian STI Management Guidelines and/or Primary Clinical Care Manual. All persons diagnosed with chlamydia should be tested for other STIs, including gonorrhoea, syphilis, and HIV.


Contact tracing is an important part of the management of most STIs. It is the responsibility of the diagnosing clinician to ensure that the process of notifying current and past partners occurs. This may be by a direct approach from the patient or their treating health professional, or by using online partner notification services, which can be anonymous. Presumptive treatment of sexual partners is recommended.

Preventive Measures

General promotion of safer sex practices, including the consistent use of condoms or dental dams with all sexual partners and for oral sex. Provision of education and counselling regarding sexually transmissible infections and negotiating safer sex.

Avoidance of any sexual contact when anogenital symptoms are present and/or for seven days after treatment has been administered for a confirmed infection. To avoid re-infection, advise no sex with partners from the last six months until partners have been tested and treated. Re-testing for reinfection at three months is recommended as reinfection rates are approximately 30 per cent.

Contact Details of Queensland Health Sexual Health Services


Australasian Society for HIV Medicine, 2010. Australasian Contact Tracing Manual (4th ed).

Australasian Society for HIV Medicine (2014). Australian STI Management Guidelines for use in Primary Care. Accessed 14 October 2014.

Cohen J, Powderly WG, 2003. Infectious Diseases, (2nd ed). Mosby: Washington.

Heymann D.L. (Ed), 2015. Control of Communicable Diseases Manual, (20th ed). American Public Health Association: Washington.

Holmes K.K, et al, 2008. Sexually Transmitted Diseases (4th ed). McGraw, New York.

McMillan A and Scott GR. 2000. Sexually Transmitted Infections (2nd ed.)

Royal Australian College of General Practitioners, 2012. Guidelines for preventive activities in general practice (8th ed). East Melbourne.

The State of Queensland (Queensland Health) and the Royal Flying Doctor Service (Queensland Section), 2013. Primary Clinical Care Manual. Cairns.

University of New South Wales, 2014. HIV, viral hepatitis and sexually transmissible infections in Australia Annual Surveillance Report 2014. UNSW, Sydney.

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Last updated: 5 May 2016