Sexually transmitted infections (STIs)

Who is most at risk of STIs?

Sexually transmitted infections (STIs) or sexually transmitted diseases (STDs), once called venereal diseases, are among the most common of the contagious diseases. As the name of this group implies, these infections can be contracted through vaginal, anal or oral sex.

You may be at high risk of an STI if you have (or have had):

  • many sexual partners;
  • sex with someone who has had many sexual partners; or
  • sex without a condom.

You are also at high risk for some of these diseases — notably HIV/AIDS and hepatitis B — if you share needles when injecting intravenous drugs.

Different types of STIs

Bacterial STIs include:

  • chlamydia;
  • gonorrhoea; and
  • syphilis.

Viral STIs include:

  • HIV/AIDS;
  • genital herpes;
  • genital warts; and
  • hepatitis B (this is often not classed as an STI as sexual contact is not the main way hepatitis B is spread).

Other STIs include:

  • trichomoniasis — caused by a single-cell parasite.

How do STIs spread?

The microbes that cause most STIs are found in semen, blood, vaginal secretions and sometimes saliva. Most of the organisms are spread by vaginal, anal or oral sex, but in some cases, such as genital herpes and genital warts, they may be spread through skin-to-skin contact.

Why it’s important to identify STIs early

Some common STIs can cause long-term complications affecting fertility and general health, and many STIs are easily passed on through sexual contact. It is therefore important to detect sexually transmitted infections in their early stages where possible, so that prompt treatment can begin and further spread can be prevented. The following is an indication of some of the symptoms of these diseases. Always contact your doctor if you suspect you have an STI.

Symptoms of specific STIs

HIV (human immunodeficiency virus) infection

Soon after infection with HIV, the person may develop a flu-like illness with symptoms that can include headache, tiredness, fever, night sweats, sore throat, swollen lymph glands, diarrhoea and rash. Doctors call this a ‘seroconversion illness’, and it can happen from a few days to 10 weeks after HIV infection.

Most people recover from the seroconversion illness within a few weeks and will be seemingly well for a varying length of time. However, during this period HIV progressively damages the immune system until it is depleted enough that the patient develops AIDS — acquired immunodeficiency syndrome. The period in which the person is infected with HIV but has not yet developed AIDS lasts an average of 10 years in adults but varies considerably.

In the months or years before someone with HIV develops AIDS, they may feel tired, lose weight, have stubborn yeast infections or skin rashes, lose their short term memory or have frequent fevers. When AIDS has developed, the person may develop a range of unusual, severe infections affecting a number of organs. Unusual cancers can also occur in people with AIDS.

Chlamydia

In women chlamydia can cause a white vaginal discharge, a burning sensation when urinating, itching, painful intercourse, or vaginal bleeding that happens after sex or is not related to menstruation. Men with chlamydia can develop a clear, watery discharge from the penis.

However, often chlamydia causes no symptoms. Even so, chlamydia infection can spread from the cervix to the uterus (womb) and fallopian tubes (these carry the egg from the ovary to the uterus) in women, resulting in pelvic inflammatory disease. Pelvic inflammatory disease can damage the fallopian tubes, leading to abdominal pain, fertility problems or ectopic pregnancy (when the embryo lodges and grows in one of the fallopian tubes rather than in the uterus).

In men, chlamydia can spread from the penis to the prostate and the tubes that store and carry sperm — this can lead to fertility problems or long-term pain.

Genital herpes

Genital herpes causes itching, burning in the genital area, discomfort when urinating, a watery vaginal or urethral discharge and weeping, fluid-filled eruptions in the vagina or on the penis. However, many people with genital herpes do not notice symptoms at all.

Genital warts

People with genital warts may notice soft, cauliflower-like growths appearing either singly or in clusters in and around the vagina, anus, penis, and/or scrotal area. However, it is much more common to be infected with a genital wart virus (also called human papilloma virus or HPV) yet have no symptoms.

There is a close relationship between some types of genital warts and cervical cancer. The majority of women with a genital wart virus will not develop cervical cancer. Nevertheless, you should have regular Pap smears to make sure your cervix is healthy and talk to your doctor about whether you are eligible for vaccination that protects against the wart viruses most closely linked with cervical cancer.

Gonorrhoea

In women, gonorrhoea can cause frequent and painful urination, a cloudy vaginal discharge, vaginal itching, inflammation of the pelvic area, rectal discharge, or abnormal vaginal bleeding. Often, however, symptoms are absent or so mild that they are mistaken for those of a bladder infection.

In men, gonorrhoea can cause burning pain while urinating, painful or swollen testicles or a yellowish, white or green discharge from the penis. However, gonorrhoea may not cause any symptoms at all.

Untreated, gonorrhoea can lead to infertility in both men and women, and ectopic pregnancy in women.

Pelvic inflammatory disease (PID)

Pelvic inflammatory disease occurs when a woman’s uterus, fallopian tubes and ovaries become inflamed due to infection (usually with chlamydia or gonorrhoea, although pelvic inflammatory disease is not always due to a sexually transmitted infection). Symptoms of pelvic inflammatory disease include a yellow or green vaginal discharge that smells unpleasant, abnormal vaginal bleeding, fever, nausea and vomiting and lower abdominal pain. However, some women with pelvic inflammatory disease do not have any symptoms.

If pelvic inflammatory disease damages the fallopian tubes (these carry the egg from the ovary to the uterus), there can be complications such as infertility, ectopic pregnancy (when the embryo lodges and grows in the tube rather than in the uterus) and pelvic pain.

Syphilis

Syphilis usually first causes a painless sore on the genitals or anus, but sores are also possible in the mouth or inside the vagina or rectum, where they are not easily seen. There may also be swollen lymph nodes (lymph glands). This stage is called primary syphilis. Many people with a syphilis sore are unaware of it, increasing the risk of them unwittingly passing the infection on. (Syphilis is spread through direct contact with a sore.)

Although the sore will heal by itself, without treatment the person may develop secondary syphilis up to 2 months later. Secondary syphilis can cause weight loss, fever, rash (often on the palms and soles), patchy hair loss, sore throat, headaches, muscle pains and tiredness.

The final stage of syphilis, tertiary syphilis, can occur many years after symptoms of secondary syphilis disappear. In this stage there can be blindness, dementia, problems coordinating movement, numbness and paralysis. Tertiary syphilis can be fatal.

Trichomoniasis

Trichomoniasis is caused by a single-cell parasite that is transmitted sexually. In women, trichomoniasis usually causes vaginal itching and pain with a foamy, greenish or yellow foul-smelling discharge.

Men with trichomoniasis may have a clear discharge from the penis, irritation of the urethra or a burning sensation after urinating or ejaculating, but most men with trichomoniasis do not have any symptoms.

Last Reviewed: 27 June 2012
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References

1. MayoClinic.com. STD symptoms: common STDs and their symptoms (updated 1 May 2012). http://www.mayoclinic.com/health/std-symptoms/ID00053 (accessed Aug 2012).
2. Genital and sexually transmitted infections (revised June 2010). In: eTG complete. Melbourne: Therapeutic Guidelines Limited; 2012 Jul. http://online.tg.org.au/complete/ (accessed Mar 2012).
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