Introduction
If the traveller indulges in casual sex the risk of infection with a sexually transmitted disease is high. Gonorrhea, chlamydia and syphilis may cause serious long-term disability, especially if treatment is delayed. Chancroid and Lymphogranulonum venerium are a serious risk in poorer countries and common sex workers. Hepatitis B and the human immunodeficiency virus (HIV), the cause of AIDS, are also spread sexually. High proportions of sex workers or prostitutes are infected.

It is difficult to be sure about the risk of HIV infection in different parts of the world. However, it is clear that the infection is widespread and although the risk is high amongst homosexual and intravenous drug using groups in 'Western' countries, on a global scale it is primarily a heterosexually spread disease. Large numbers of the population in many parts of Africa are infected and AIDS is common. Infection is widespread in many countries in Asia and South America.

Precautions to Take
1. Casual sexual intercourse is risky. Condoms provide good but not complete protection.

2. The lifestyles associated with drug-taking might put the traveller in contact with people who are HIV positive and should be avoided. Needle sharing is very dangerous.

3. Unless you are absolutely certain that the equipment being used is sterile, skin-damaging procedures such as ear piercing, tattooing, acupuncture, manicure and shaving with open razors should be avoided.

4. In many developing countries re-use of medical supplies, including needles and syringes is common. Travel packs are available from some chemists and travel clinics, containing sterile injecting equipment for use in an emergency (e.g. when skin cuts need suturing, an intravenous drip or injections are required or for dental surgery). These needle kits should be supplied with a certificate showing contents and the reason for its purchase, useful for customs clearance.

5. Blood transfusion: In most of Western Europe, North America, Japan and Australasia all donated blood is now screened for HIV antibodies. However, in most developing countries there may be only the most basic blood transfusion services and much of the blood donated is unscreened. The risks from blood transfusion in such circumstances are high. Thus, points to consider are:

a. accidents are the commonest reason for needing a blood transfusion so they should be avoided where possible, e.g. driving carefully.

b. blood transfusion should only be accepted when essential.

c. pregnancy or any medical condition which may lead to heavy blood loss, should be taken into account before travelling to destinations where good medical facilities will not be available.

d. knowing your blood group in advance may make it easier to find a blood donor in an emergency.