Chlamydia is the most common bacterial sexually transmissible infection in Australia. It is compulsory to report new cases of Chlamydia to the Health Department, which keep statistics. Notification rates have risen dramatically from 47 per 100,000 in 1997 to 203 per 100,000 in 2005. The Federal Government has now funded a National sexually transmissible infection (STI) strategy, aimed at reducing the incidence and complications of Chlamydia. Chlamydia is important as it often remains unnoticed and can cause fertility problems due to tubal damage.

Chlamydia in Detail

C. Trachomatis is a bacterium that lives within the cells that line the cervix. It may spread vertically through the cavity of the uterus and fallopian tubes, affecting the lining of the abdomen and pelvis. Fortunately Chlamydia is easy to diagnose and easy to treat often with a single dose of antibiotics. Chlamydia is generally spread during sex, either anal or vaginal. The risk of getting Chlamydia is greater if you have a new sexual partner, more than one sexual partner or if you have had Chlamydia before. Condoms are protective against Chlamydia.

Chlamydia Symptoms

Chlamydia may infect without symptoms. It is easy to spread Chlamydia without even knowing you are infected. Up to 50% of women with Chlamydia have no symptoms at all. Of those who do, the most common symptoms include vaginal discharge, abnormal bleeding (either heavy, or irregular periods), abdominal pain, pain with sex or pain with urination. Male symptoms may include burning or pain with urination, discharge from the penis, pain or tenderness of the testicles or swelling of the scrotum.


Chlamydia is easy to diagnose with a swab taken from within the endocervical canal (the hole in the centre of the cervix). This is able to detect about 99% of Chlamydia infections. A urine test can also be used which is almost as accurate. Note that no diagnostic test is 100% accurate. It is now recommended that all sexually active women under the age of 25 should have annual screening tests for Chlamydia even in the absence of symptoms.

Testing for other sexually transmissible infections

If you or your sexual partner is diagnosed with an STI like Chlamydia it is worth considering screening for other infections such as HIV, Gonorrhea, Hepatitis B or Hepatitis C or Syphilis. These will usually require a blood test.

Chlamydia Complications

Untreated Chlamydia, in women, can lead to a serious infection called Pelvic Inflammatory Disease (PID, see other document on this website). If Chlamydia is not treated about 30% of women may develop PID. PID can, if left untreated, cause scarring of the fallopian tubes, which can lead to fertility problems, increase risk of ectopic pregnancy, or acute and chronic pelvic pain. After an initial episode of severe PID the risk of tubal damage is 25% and subsequent episodes will add to this risk.

Who gets Chlamydia and what are the risk factors?

  • Younger age. 15-35 years old are at highest risk
  • Use of non barrier contraception (although use of the combined OCP is somewhat protective in its own right due to thickening of cervical mucus)
  • Those with an unplanned pregnancy (usually implies recent unprotected sex)

Chlamydia treatment

Chlamydia treatment is the same for men and women. Most infections can be cleared by a once off antibiotic treatment, taken by mouth, called azithromycin. Azithromycin is safe to take during pregnancy. Anyone who is allergic to azithromycin (or erythromycin) can take doxycycline, which must be taken twice daily for seven days. Doxycycline is generally not recommended during pregnancy.

Sexual partner treatment

Treatment is important for you and anyone you have had sex with recently. You need to get your partner or recent partners to be tested by his or her own doctor. You should not have sex until you and your partner have been treated. The antibiotic treatment has a very high rate of clearance of Chlamydia so generally you don’t need to be retested however many women prefer to be retested for the satisfaction of knowing that the Chlamydia has been cleared. Please note, that the swab test used may detect dead Chlamydia organisms, and may remain positive for several weeks after treatment.

Prevention of Chlamydia

The most effective way to prevent Chlamydia infection is to use barrier contraceptives (condoms are the most effective) and frequent screening. The oral contraceptive pill is also protective against Chlamydia, although this cannot be used as the only means of prevention. Therefore, if you are taking the oral contraceptive pill and have a new partner it would still be wise to use condoms. Because the complications of Chlamydia infection grow more severe with time, treatment should commence at the first sign of suspicion of Chlamydia infection. Antibiotic treatment should be undertaken even before the diagnosis is confirmed by swab tests.

For more information see

This is the website for the centre for disease control Atlanta, a world-renowned infectious diseases organization.,mediacentre/factsheets/en/

This will take you to the media centre and factsheets for the World Health Organization, also a very reliable source.

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