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Sexually transmitted diseases Knowledge
What is a sexually transmitted disease (STD)?

An STD is an illness that is spread through sexual contact.

How can sexually transmitted diseases be avoided?

  • The less sexual partners a person has, the lower the risk of infection.

  • Most sexually transmitted diseases can be avoided to a large extent by practicing safe sex (eg using condoms).

  • Most sexually transmitted diseases can be cured if they are diagnosed and treated in their early stages.

The most common diseases and their symptoms are described below.


Chlamydia is the most common and fastest spreading sexually transmitted disease in the UK. It stems from a bacterium, Chlamydia trachomatis.

Women diagnosed with Chlamydia can also infect their newborn infant during delivery. Symptoms usually appear approximately 7 to 21 days after infection and differ for men, women and children.

Symptoms in men:

  • inflammation of the urethra (the bladder duct within the penis)

  • stinging feeling when passing water

  • clear discharge from penis and possible itchiness around the opening

  • pain or tenderness in the testicles.

Symptoms in women:

  • stinging feeling when passing water

  • unusual vaginal discharge

  • pain caused by pelvic inflammation (pelvic inflammatory disease)

  • pain during intercourse

  • in some cases, bleeding between periods.

Symptoms in infants:

  • inflammation of the eye (conjunctivitis) at birth

  • problems breathing

  • premature birth

  • in rarer instances, pneumonia.

One of the most common ways of testing for Chlamydia is for the GP to collect a cell sample from the infected area (cervix or penis) with a cotton swab. This is then sent to a laboratory for evaluation. In the absence of a firm diagnosis, you may be referred to a specialist genitourinary clinic for further testing. Treatment consists of antibiotics, and should also be given to the patient's partner. A further swab is recommended once treatment has ended to check whether the infection has cleared. For more information, read the factsheet on chlamydia.


Gonorrhoea is caused by Neisseria gonorrhoeae, a bacteria that grows and multiplies quickly in moist, warm areas of the body such as the cervix, urethra, mouth, or rectum. In women, the cervix is the most common site of infection. However, the disease can also spread to the uterus (womb) and fallopian tubes, causing pelvic inflammatory disease leading to infertility. Gonorrhoea is most commonly spread during genital contact, but can also be passed from the genitals of one partner to the throat of the other during oral sex. Gonorrhoea of the rectum can occur in people who practice anal intercourse. In pregnant women, gonorrhoea can be passed from an infected woman to her newborn infant during delivery if left untreated.

The early symptoms of gonorrhoea are often mild, and many women who are infected have no visible symptoms of the disease. If symptoms of gonorrhoea develop, they usually appear within 2 to 10 days after sexual contact with an infected partner, although a small percentage of patients may be infected for several months without showing symptoms.

Symptoms in women include:

  • painful, burning sensation when urinating

  • yellowish or bloody discharge from the vagina

  • bleeding between periods

  • abdominal pain.

Men are more likely to show symptoms than women. Some of the symptoms in men include:

  • burning sensation during urination

  • yellowish-white discharge from the penis.

Other symptoms affecting the rectal area include itching, discharge and sometimes painful bowel movements.

A diagnosis is made through detection of bacteria in samples taken from the urethra, cervix, throat or rectum. The condition is treated with antibiotics, and treatment should also be given to the patient's partner. As with Chlamydia, further testing is recommended once treatment has ended to check whether the infection has cleared. For more information, read the factsheet on gonorrhoea.

Herpes genitalis (genital herpes)

Gential herpes is a highly contagious viral condition caused by the herpes simplex virus (HSV). It principally infects the skin and mucous membranes of the genitals and rectum, but can also appear in areas such as the mouth. It is transmitted primarily through physical and sexual contact. During birth, the presence of herpes simplex virus on the genitalia or in the birth canal is a threat to the infant. Infection in the newborn infant can lead to herpetic meningitis, herpetic viremia (herpes virus particles present in the blood) and chronic skin infection.

The symptoms of herpes simplex virus usually occur a week after infection, but sometimes take longer to appear. Initially, the skin becomes reddened and multiple small blisters filled with a clear, straw-coloured fluid appear. Prior to the presence of blisters, the infected individual may also experience increased skin sensitivity, tingling, burning or pain at the site where blisters will appear. Later, the blisters burst leaving shallow, painful ulcers which eventually scab and heal over a period of 7 to 14 days.

The outbreak may be accompanied by other symptoms such as:

  • swelling and tenderness of the lymph nodes in the groin area.

  • in women, vaginal discharge and painful urination.

  • in men, a possibility of painful urination if the lesion is near the opening of the urethra.

  • fever.

In most cases, a description of the condition and the appearance of the blisters will be enough to make a diagnosis. The GP may also advise referral to a specialist genitourinary medicine (GUM) clinic for confirmation of the diagnosis.

There is no cure for the herpes simplex virus; once infected, patients will remain a carrier for the rest of their lives. Some remedies, however, can reduce the duration of the eruption. In addition, by being more aware of the initial symptoms of recurrence (skin sensitivity and tingling), timely treatment with medication such as aciclovir (Zovirax tablets/suspension) will often abort the outbreak of blisters.

The best way to avoid transmission is to avoid direct contact with an open lesion. People with herpes simplex virus should avoid sexual contact when active lesions are present.

Although the symptoms of genital herpes may not be present, it is important for those infected to inform their partner that they have the disease. This will encourage both parties to use barrier protection (condoms) to prevent the spread of the illness. Using condoms and not sharing towels are good ways of reducing the chance of infection in the first place. For more information, read the factsheet on Herpes genitalis.


AIDS is a potentially lethal sexually transmitted disease and is caused by the HIV virus. HIV invades and destroys the immune system, which protects the body from infection. This means that a person who carries the HIV virus is prone to many different illnesses and may die from diseases that are harmless to healthy people.

AIDS is still most widespread south of the Sahara in Africa, Asia, and the Caribbean islands, and is more common among homosexual and bisexual men. However, in more developed countries the disease is becoming more frequent among heterosexuals, especially young people. In the UK, new cases of HIV are now more prevalent among heterosexuals.

Intravenous drug users and people with many different partners are particularly at risk from HIV. The virus is found in bodily fluids such as blood, sperm and vaginal secretions, and can pass through little scratches that may occur during sexual intercourse.

Although they vary considerably, the symptoms include:

  • fever

  • diarrhoea

  • sweating at night

  • loss of weight

  • swollen glands

  • general discomfort.

The diagnosis is made when the HIV antibody is found in the blood. The test is not usually positive until 6 to 12 weeks after infection.

There is no cure for HIV and AIDS, but the earlier the diagnosis is made, the easier it is for the doctors to help. Today, efficient treatments exist that increase quality of life and prolong life itself. Anyone who is infected with HIV should only have safe sex using barrier protection and inform all previous partners about their infection. For more information, read the factsheet on AIDS and HIV.

Genital warts

Warts, or condylomata acuminata, are caused by the human papilloma virus (HPV). Up to nine months can pass from the time of infection to the actual development of warts. In women, human papilloma virus can lead to changes in the cervix and to the development of cervical cancer. Therefore, it is important that this condition is diagnosed and treated.

The symptoms are raised, rough, wart-like growths that may occur singly or in clusters. In men, they are usually found around the head of the penis and tend to be drier. In women, they appear most often around the vaginal opening and may spread to the rectal area. It is also possible for the virus to appear on or near the cervix as whitish, flat-like lesions, usually only detectable through close visual examination of the cervix (colposcopy). In both men and women, lesions may also be present in the mouth and throat. In general, symptoms can intensify if the immune system is weakened, or during pregnancy or if the person has diabetes. The warts are very contagious so safe sex is advisable.

A diagnosis is made when a characteristic lesion is visible. By swabbing the skin with 5 per cent acetic acid, 'invisible' warts will emerge as white-coloured patches. A GP can treat the warts by freezing and swabbing, but if this does not help the patient may be referred to a genitourinary specialist who can offer more specialised treatment. However, it is important to note that treatment does not always offer a complete cure. For more information, read the page on genital warts.


Syphilis is a dangerous and life-threatening bacterial disease. After infection, the bacteria is transported through the body via the bloodstream and adversely affects vital organs such as the heart, brain, nervous system and spine.

The symptoms are divided into three stages.

Up to 12 weeks after the time of infection:

  • one or more red lesions will develop on the penis, labia (lips of the vagina), anus and sometimes on the mouth and lips. These lesions disappear after a week.

Up to six months after the time of infection:

  • a red rash appears on the chest, back, arms, legs, hands and soles of the feet

  • high fever

  • sore throat

  • muscular fatigue

  • general feeling of discomfort.

Anyone experiencing these symptoms should contact their doctor immediately.

If the illness is not treated by the second stage, it will disappear for a while. However, the disease can lie dormant in the body and return up to 20 years later. At this more advanced stage the symptoms will be:

The diagnosis is made through the detection of the micro-organism or the detection of antibodies in the blood. In its early stages, syphilis can easily be treated with antibiotics. For more information, read the factsheet on syphilis.

How to avoid sexually transmitted diseases (STDs)

Avoid high-risk behaviours and practise safe sex.

  • Though not necessarily practical or desirable, abstinence is the only way to completely prevent STDs.

  • Avoid sex with many different partners.

  • Always use condoms.