Causes of Sexually Transmitted Diseases

Causes of Sexually Transmitted Diseases

Sexual intercourse can be one of the most rewarding experiences people may have. Sometimes, however, it may be the cause of a disease, with more or less serious consequences. Such a disease is called a venereal disease (named after Venus, the Greek goddess of love). Venereal diseases are nowadays better known as sexually transmitted diseases or STDs.

Venereal diseases have a long history. In former times, when their cause was not known, and treatment was not possible, they were considered more of a moral than a medical problem. It was thought that contracting such an infection was the just punishment for sexual debauchery. Since the beginning of this century new medicines have been developed, and many sexually transmitted diseases can now be treated with success. However, for some people sexual matters are still taboo. One of the reasons for the increased frequency of various sexually transmitted diseases is that people often hesitate too long before going to a doctor. In the meantime the disease may have spread to various sexual partners. And it may already have caused irreparable damage to the body. Among the sexually transmitted diseases there are well known infections such as gonorrhoea and syphilis. But also lesser known infections are of importance, such as genital herpes*, and diseases seen mainly in the tropics, such as granuloma inguinalis. With the development of ‘sex tourism’, however, it may be expected that ‘tropical’ venereal diseases will become more common world-wide.


Sexually transmitted diseases are caused by various organisms, but each disease has in principle the same pattern of transmission. The organisms that cause such infections depend on the warmth and moisture of the sexual organs for survival. They die if the temperature drops much below that of body heat. This is the reason why under normal circumstances a sexually transmitted disease can only be contracted by a person coming into direct contact with infected mucous membranes. This contact is usually in the form of genital intercourse, although oral and anal sex can lead to infections of the mouth, throat and anal regions. In poor hygienic conditions sometimes indirect transmission may occur, for example via a towel when this has been used a short time before by someone who has a sexually transmitted disease.

Not only adults may be infected by venereal diseases. During and after pregnancy, it is also possible for the child to contract such an infection from the mother. In the last months of pregnancy the causative agents of syphilis may infect the child. When the mother has gonorrhoea or genital herpes, the child may be infected during birth.

Risk groups

As is obvious from the name, most of the time one can get a sexually transmitted disease only by having sex. Total sexual abstinence would not be a very practical suggestion however. When two people only have sex with each other the risk of catching venereal disease is minimal. The risks increase for someone who has frequent sexual contacts with a number of different partners; in particular if the partners have adopted the same lifestyle. It is often thought that sexually transmitted diseases are confined to homosexuals. This is not the case, however. If one takes into account the number of partners, heterosexuals and male homosexuals run the same risk of being affected. Because of the nature of their sexual contacts, lesbian women are affected less often. Since the 1950s sexually transmitted diseases have become more common. (Partly this is the result of better record-keeping, but it is

obvious that this is not the whole story.) In most . western European countries, the figures for sexually transmitted diseases have increased by about a third in the last ten years. There has been much discussion on the causes for such an increase. One popular opinion is that the introduction of the contraceptive pill has led to increasing sexual permissiveness and has therefore contributed to the spread of venereal diseases. There is much doubt, however, whether this opinion holds true. A more probable explanation is that the introduction of the pill has reduced the use of another method of contraception, the condom. It is a well known fact that the condom is a good method of preventing the transmission of disease, although it is not 100 per cent effective as a contraceptive or disease-preventer.


Sexually transmitted diseases constitute a serious danger to general health. Because the diseases are so contagious, one person may have infected many others, before symptoms are noticed and treatment provided. Besides this, there may be serious consequences for the person who has contracted the disease. If, for example, syphilis is left untreated, irreparable damage to various organs may result. If gonorrhoea is allowed to spread from the initial site of infection, it may reach the Fallopian tubes in women or the epididymis in men. Gonorrhoea is a major cause of infertility in both men and women, because an infection of these tubes leads to scarring, which may block the passage of sex cells.

If a pregnant woman contracts a sexually transmitted disease, her child also runs a risk of being infected. In the last months of pregnancy, the placenta is permeable to the organisms that cause syphilis. In the developing child this may lead to various congenital abnormalities. During birth the gonorrhoea bacteria may infect the eyes of the baby. In many countries, therefore, every baby gets eyedrops, which kill any bacteria that are possibly present. Similarly, if a pregnant woman has genital herpes in an active form, everything should be done to avoid the child being infected. Because the immune system is not yet fully developed, the child cannot cope with the herpes virus. Sometimes it is therefore necessary to deliver the baby by Caesarean section.

Sexually transmitted diseases may manifest themselves through various symptoms. A burning feeling when urinating, itching or a discharge from the penis or the vagina are just some of the phenomena that call for a thorough medical examination. The symptoms may be the result of an innocent fungal infection, but certainty is best obtained by a visit to a doctor or in a specialized help centre. Sometimes, however, a sexually transmitted disease may produce hardly any localized symptoms at all.

If someone knows that he or she may have contracted such an infection, possible warning signs are a continuous raised temperature and a prolonged feeling of tiredness.


The world’s most common sexually transmitted disease is gonorrhoea. The infection is caused by the bacterium Neisseria gonorrhoea, or gonococcus. It is an infection of the genito-urinary tract. In men, some four days after being infected, a thick yellowish green discharge drips from the urethra, and there may be discomfort and a burning sensation as urine is passed. If the disease is not treated at this stage, it spreads up the urethra to the prostate gland and bladder, and sometimes the testes can become inflamed. As mentioned above there is a risk of permanent damage, causing infertility. The majority of infected women show no symptoms at all; others have a slight vaginal discharge or experience a burning feeling on passing urine. Just as in men there is a risk that infertility will develop. Fortunately, gonorrhoea is easily treated with antibiotics such as penicillin.


The first sign of this disease appears after an incubation period of two to six weeks from infection in the form of a sore called a chancre. Most of the time it develops on the penis or the vulva, but sometimes the lesion develops on the cervix or in the anus, and so is unlikely to be detected. The sore is painless and feels hard underneath. Because it disappears of its own accord after a few weeks, sometimes it is presumed that nothing is the matter. This is a false presumption however, because the disease continues to develop. Several weeks later syphilis enters its second stage, usually showing itself as a non-itchy rash that appears all over the body. There may also be painless swelling of the lymph glands in the groin or the armpits. This rash likewise disappears after several weeks. The last stage of syphilis is very serious. In various organs of the body ulcer-like lesions appear. These lesions cause irreversible damage. Examples of affected organs are the heart valves, the brain and the spinal cord. Nowadays however, there is no need for anyone to suffer the symptoms of this last distressing stage because a course of penicillin can provide an effective cure if given early enough.

Genital herpes

The cause of this sexually transmitted disease is a virus, that is very similar to the virus that causes the common cold sore. The blisters characteristic of genital herpes are generally situated on the shaft of the penis or on the entrance of the vagina. The blisters eventually burst and form shallow painful ulcers. At the same time, the glands in the groin swell up and feel painful and the sufferer may feel generally unwell and have a raised temperature. Such an attack usually lasts between one and two weeks.

The problem with genital herpes is that in around half of the sufferers the virus retreats into the nerves and becomes dormant for a time. Over the following months or even years it can reactivate to produce recurrent attacks. Fortunately, these tend to be progressively less frequent and also milder. At the present time there is no effective treatment, and therapy has to be confined to soothing ointments and sexual abstinence during the active stages of the disease.

Other diseases

Not all diseases that affect the sexual organs are sexually transmitted, although sexual contact is the most common way by which they are spread.

Of all the sexually transmittable diseases, non-specific urethritis (NSU) is the most prevalent. The symptoms are very similar to those of gonorrhoea.

The incubation period before symptoms are first noticed varies between two days and three months. A discharge from the penis or vagina, which can be heavy or light, usually alerts the person that he or she has caught an infection. Occasionally, NSU can cause sufficient discomfort for the patient to retain urine rather than emptying his or her bladder. In other cases, blood may be passed with the urine, which may convince some people that they have a more serious disorder, such as cancer. Other symptoms include pain on ejaculation in men and an irritating feeling of ‘itching’.

Treatment of NSU is with a course of antibiotics. If tetracycline is prescribed, patients would do well to reduce the amount of dairy produce in their diet because it may interfere with the absorption of the drug. Sexual intercourse should also be avoided because it may aggravate the condition. Similarly, men should abstain from milking the urethra to draw out discharge because this tends only to prolong the infection.

Not strictly speaking a disease, ‘crabs’ are nonetheless usually transmitted from person to person through sexual contact, although they can also be caught from toilet seats and infested towels or sheets.

An adult crab louse is about 2mm across and has minute claws with which to cling to body hair. The most common sites of infestation are the pubic area, and the armpits. In some cases even the eyebrows are affected. The crabs feed by making a small puncture in the skin of their host through which they draw blood. Anyone, even those with the most scrupulous personal hygiene, can catch crabs. No-one should therefore delay going to a doctor through embarrassment that they will be thought of as being somehow ‘dirty’. An insecticide painted over the affected areas is the most common method of treatment.


A sexually transmitted disease that was discovered only a short time ago – in 1979 – is Acquired Immune Deficiency Syndrome, commonly known as AIDS. The enormous attention paid to this disease by the media has sometimes led to hysterical reactions. Relatives of AIDS sufferers have been known to avoid physical contact for fear of being infected and sometimes even hospitals have refused to treat them. Such reactions lack any basis in reason, because the virus that causes AIDS is transmitted only by sperm or blood.

The first symptoms of the disease are caused by the weakening of the body’s immune system, leaving it open to infections that normally are relatively harmless. Sufferers often catch pneumonia, and experience fever, loss of weight, diarrhoea and enlargement of the lymph glands.

As yet there is no cure for AIDS, although some success has been achieved in the United States with implants of embryonic thymus tissue. This tissue is thought to re-establish the normal immune defences of the body.

Treatment of sexually transmitted diseases

When a sexually transmitted disease is diagnosed there are several steps to be undertaken. First, there is of course the treatment of the disease itself. With

the most common venereal infections this is usually no problem. Sometimes, however, a person may have contracted two or even more infections at the same time. It is therefore advisable to return to the clinic at regular intervals to have the necessary check-ups.

The next step is to test for the disease in the partner(s) of the patient. Ideally, the patient should tell his or her sexual contacts that they may have been infected. Most of the time this is a rather embarrassing situation; however, partners may instead be visited by trained personnel from a VD clinic. When this policy is adopted, the name of the person who has given the information that they may be infected is usually kept secret. Clearly it is extremely difficult to track down the partners of someone who has frequent and changing sexual contacts. The best way therefore to prevent spreading a sexually transmitted disease – or contracting one – is to limit the number of one’s sexual partners. Next to using a condom this is the most safe way to continue having a rewarding sex life, without the constant fear that this pleasure will be destroyed in one way or another.