On this page
- Key messages
- Notification requirement for chlamydia
- Primary school and children’s services centre exclusion for chlamydia
- Infectious agent of chlamydia
- Identification of chlamydia
- Incubation period of Chlamydia trachomatis
- Public health significance and occurrence of chlamydia
- Reservoir of Chlamydia trachomatis
- Mode of transmission of Chlamydia trachomatis
- Period of communicability of chlamydia
- Susceptibility and resistance to chlamydia
- Control measures for chlamydia
- Outbreak measures for chlamydia
- Chlamydia must be notified by pathology services in writing within 5 days of diagnosis.
- Chlamydia trachomatis infection has become a major public health problem because of the associated long-term consequences of infection, especially pelvic inflammatory disease in women.
- Preventive measures include education about safe sex practices.
Notification requirement for chlamydia
As of 1 January 2023, pathology services must also notify notification details for all tests performed during a weekly period in relation to chlamydia trachomatis. This notification must be in writing within five business days of the end of that period.
Chlamydia is a ‘routine’ notifiable condition and must be notified by pathology services in writing within 5 days of diagnosis. Medical practitioners are not required to notify cases of Chlamydia.
This is a Victorian statutory requirement.
Medical practitioners have a statutory obligation under the Children, Youth and Families Act 2005 to notify the department’s Child Protection Services, if they believe a child is in need of protection because of sexual abuse.
Primary school and children’s services centre exclusion for chlamydia
Exclusion is not applicable.
Infectious agent of chlamydia
Chlamydia trachomatis serogroups D–K cause genital disease.
Identification of chlamydia
Most women with urethral or endocervical chlamydial infection are asymptomatic.
Clinical manifestations may include:
- vaginal discharge
- postcoital or inter-menstrual bleeding.
Less frequent manifestations include urethral syndrome (dysuria and pyuria), bartholinitis, perihepatitis and proctitis.
Complications and sequelae can result in pelvic inflammatory disease, which may manifest as chronic pelvic pain, infertility and ectopic pregnancy. Infections during pregnancy may cause preterm rupture of the membranes and preterm delivery. There is an association with spontaneous abortion. It can also cause conjunctivitis in the newborn and pneumonitis in the young infant.
The primary presentation of chlamydial infection in males is urethritis (penile discharge, pruritis and dysuria) but, again, infection is often asymptomatic.
It is the most common cause of urogenital infections in men under the age of 35. Possible sequelae and complications of male urethral infection other than urethritis include:
- prostatitis and infertility
- reactive arthritis
Receptive anal intercourse in men who have sex with men may result in chlamydial proctitis (which may manifest as pain, rectal discharge or bleeding).
Testing individuals at high risk of chlamydial infection is recommended.
High-risk individuals include those with a clinical presentation suggestive of chlamydial infection, individuals attending general practitioners for testing of sexually acquired infection (STI); those attending STI clinics, family planning clinics and gay men’s health centres; and partners of those already diagnosed with an STI.
Currently, the primary mode of diagnosis is first-pass urine testing with polymerase chain reaction (PCR) techniques. It is imperative than Neisseria gonorrhoeae also be tested for when testting for C. trachomatis.
Other laboratory investigations currently available are:
- cell culture (only in specialised laboratories – reserved for research purposes)
- antigen assays, including direct immunofluorescence or enzyme immunoassay
- hybridisation assays such as the DNA probe.
Nucleic acid amplification tests
The choice of test depends on the specimen type submitted, the cost of the test, the sensitivity and specificity of the test, and the expertise and size of the laboratory.
Nucleic acid amplification tests (NAATs) have become the test of choice because of their widespread availability, their high sensitivity and specificity, and their non-invasive nature (that is, their ability to be used on first void urine samples for the diagnosis of genital infections in both men and women).
Incubation period of Chlamydia trachomatis
The incubation period is poorly defined but is probably 7–14 days or longer.
Public health significance and occurrence of chlamydia
Infection with C. trachomatis has become a major public health problem because of the long-term consequences of infection experienced predominantly by women. These relate mainly to the development of pelvic inflammatory disease and include chronic pelvic pain, ectopic pregnancy and infertility. Rarely, males may also become infertile.
Chlamydia is the most commonly notified curable sexually transmissible bacterial disease in Victoria. It affects both genders. The annual number of notified cases has increased 19-fold since the early 1990s (which may in part be explained by increased testing with newer, more sensitive tests). The majority of infections are notified from individuals under 30 years of age.
The prevalence of chlamydial genital infections in Australia has not been comprehensively established but it has been estimated to be 2.5–to 14% in sexually transmitted disease clinic patients, 5% in family planning clients, and up to 15% in commercial sex workers.
While the spontaneous cure rate has been estimated at 7.4%, immunity following infection is thought to be type specific and only partially protective. As a result, recurrent infections are common.
Risk factors for chlamydial infections include a relatively high number of sexual partners, age of first intercourse, a new sexual partner and lack of use of barrier contraceptive measures.
The presence of chlamydial infection should prompt consideration of screening for other sexually transmissible infections, in particular gonorrhoea and HIV. Endocervical C. trachomatis infection has also been associated with an increased risk of acquiring HIV infection and may also increase HIV infectiousness.
Reservoir of Chlamydia trachomatis
Humans are the reservoir for C. trachomatis.
Mode of transmission of Chlamydia trachomatis
Transmission of C. trachomatis occurs primarily by sexual contact. Mother-to-baby transmission occurs when mothers colonised with C. trachomatis infect their babies as they are born vaginally.
A high proportion of infections in women are asymptomatic, resulting in untreated disease, ongoing transmission and an increased risk of sequelae.
Period of communicability of chlamydia
The period of communicability is unknown but may be months to years.
Susceptibility and resistance to chlamydia
Everyone is susceptible to infection.
Control measures for chlamydia
Preventive measures include education about safe sex practices such as use of condoms and early detection of infection by testing those at risk.
Control of case
Azithromycin or doxycycline are used as first-line antimicrobials to treat chlamydial infection. Advice on the treatment of chlamydial infections can be found in Therapeutic guidelines: antibiotic and the Australian STI Management
Specialist consultation should be sought for complicated or disseminated infections.
Testing for reinfection of treated cases should be delayed until 3 months after initial infection.
Control of contacts
Sexual partners of individuals with chlamydial infection should be examined and investigated and then treated empirically. Advice on treatment options for contacts can be found in the Australian STI Management and Victorian guidance on patient delivered partner therapy (PDPT) for chlamydia.
Contact tracing assistance can be provided by the department’s notification officers.
Control of environment
Outbreak measures for chlamydia
Reviewed 19 December 2022