Depending on the nature of the sexual assault you have experienced, you may be concerned about contracting a sexually transmitted infection (STI).

History shows that your risk of catching an STI from a sexual assault is, in fact, quite low. However, the only way to be certain is to be tested. Unfortunately, testing directly after the assault will not be helpful in determining whether you have been exposed to an STI. You have to wait 2 weeks to detect infections such as chlamydia, and at least 3 months for infections such as hepatitis and HIV.

Until you get the all-clear from these tests, it is recommended you practise safe sex, such as using condoms to protect your partner.

Gonorrhoea and chlamydia
After 2 weeks, you can be tested for both gonorrhoea and chlamydia. These days, this is usually done by means of a simple urine test, although it can also be done via a swab of the vagina or penis.

It is important to be tested for these diseases as they can remain 'silent', with no symptoms for many years, potentially causing serious consequences, such as fertility problems in women. Both gonorrhoea and chlamydia can be treated effectively with antibiotics.

You should also have a swab taken at this time if you have any unusual vaginal discharge or discomfort. Another STI, trichomonas, can be detected and is readily treatable, as are other infections that are not necessarily sexually transmitted, such as gardnerella and candidiasis (also known as thrush).

HIV, hepatitis B and syphilis
After 3 months, you can have a blood test to check for infection with HIV, hepatitis B and syphilis. Syphilis is readily treatable with antibiotics.

Although many people are particularly concerned about contracting HIV, the risk of developing HIV after a sexual assault in Australia is very low. However, if you are considered to be at high risk of contracting hepatitis B or HIV, you may be offered post-exposure prophylaxis (PEP).

For hepatitis B, if you have not already been immunised, PEP will involve an injection of the vaccine, the first in a course of three. Subsequent injections will be needed at one and 6 months after the initial shot to ensure full immunity.

For HIV, PEP is a combination of drugs that may help to prevent HIV infection from developing. However, these drugs can have serious and unpleasant side-effects, so you need to discuss the risks and benefits with your doctor.

Genital warts and genital herpes
Finally, there are some STIs for which testing is not reliable, in particular genital warts and genital herpes.

It is estimated that 80 per cent of all adults have blood evidence of having been exposed to the wart virus, so blood tests are unlikely to be helpful. There is also a highly variable latency period, which means the virus can be present for many years before showing symptoms. Hence, it is often a case of wait and see, and your doctor may prescribe treatment if a problem arises.

For women, certain strains of wart virus can lead to cancer of the cervix, so it is important to have regular Pap smears to detect any changes early.

The best test for genital herpes is a swab of the blisters that occur when the disease is active. Unfortunately, there is no cure for herpes, but medication is available to manage the symptoms and prevent outbreaks.