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Sexually Transmissible Diseases and Sensible Precautions for Traveling to Indonesia

Sexually transmissible diseases (STDs) are the most common easily preventable infectious conditions that affect travellers and expatriate residents worldwide. Their unacceptably high incidence is underlined by the recent emergence of a (presently) incurable and lethal pathogen: the human immunodeficiency virus (HIV), responsible for the condition known as acquired immune deficiency syndrome (AIDS).

Studies from around the world show that although knowledge of STDs is increasing amongst travellers, intellectual knowledge has little effect on with actual behaviour. Being better-informed has resulted in a modest increase in the use of condoms and self-control, and there is abundant evidence that a wide variety of risky and sometimes fatal sexual behaviours are carried out by people who, to use the old cliché, ought to know better.

Many diseases are known to be spread by sexual contact. Besides bacterial diseases such as chlamydia, gonorrhoea, and syphilis, there are also essentially untreatable viral infections such as venereal warts, hepatitis, and herpes. There are also parasitic infections such as crabs and amoebic/giardia infections.

In developing countries, syphilis is common; figures vary from 5-20% in women attending antenatal clinics to 70% in certain high-risk groups such prostitutes. This is often attributed to the fact that syphilis often goes undiagnosed. Gonorrhoea is equally common, and while easier to suspect and diagnose is becoming increasingly difficult to treat due to bacterial drug resistance. Non-gonococcal urethritis in men is caused by chlamydia C trachomatis in at least 40% of cases; the female counterpart to NGU frequently causes pelvic inflammatory disease. Chlamydia is significantly harder than gonorrhoea to diagnose and treat.

There is virtually no published data on herpes in developing countries, although based on studies available it accompanies other STDs in at roughly 20% of cases reported. Venereal warts are three times more common than herpes, and a key sequelae, cervical cancer, is a very severe health complication.

Chancre is endemic in many developing countries, particularly in SE Asia, Eastern and Southern Africa, and Papua New Guinea. It is as unpleasant as it sounds, and prostitutes are an important vector in its spread. Most genital ulcers are due to chancroid, though mixed infections are common.

Viral infections principally affecting the liver are among the STDs with the highest incidence world-wide. The most important of these is the hepatitis B virus, estimated to be responsible for chronic infection in at least 300 million individuals and the ninth most common cause of premature mortality. 75% of these carriers live in Asia and the Far East. Sexual activity is one of the most common forms of HBV transmission, as estimates are that 1 in 2,500 travellers return home with sexually-acquired hepatitis B.

Fortunately, hepatitis B is the first hepatitis virus for which a vaccine was developed, and indeed the first sexually transmitted disease against which there was an effective vaccine. Recently, preliminary evidence has been forthcoming to suggest that a previously unsuspected transmission vector, via bed bug bites, may be a significant source of infection.

The hepatitis A virus is spread by the faecal-oral route, and sexual transmission among homosexual men represents a significant factor for its spread. The hepatitis C virus is also transmitted by sexual contact.

Sexual transmission of HIV accounts for about three quarters of all infections world-wide, the majority of which happened through heterosexual activity. There are three dominant patterns of HIV transmission:

  • Pattern 1 is predominant in North America, Western Europe, Australia and New Zealand. Sexual transmission occurs principally among homosexual and bisexual men, but heterosexual transmission also occurs and appears to be increasing. Transmission through blood occurs principally as a result of intravenous drug use. Perinatal infection is less common, because relatively few women have been infected.
  • Pattern 2 is predominant in sub-Saharan Africa and increasingly in Latin America and the Caribbean. Sexual transmission is predominantly heterosexual while transmission via contaminated blood transfusion continues in areas where blood screening is not yet routine. Perinatal transmission is a major problem since in some areas 5-15% of pregnant women are infected.
  • Pattern 3 is predominant in North Africa, the Middle East, Eastern Europe, Asia and Pacific Rim countries. These areas until recently only accounted for a small proportion of overall AIDS cases reported. Additional infection resulted from contact with people in Pattern 1 and 2 areas or from exposure to imported blood. However, indigenous transmission of HIV-1 infection is increasing, particularly among prostitutes and drug users. Indeed, it is becoming apparent that India and South East Asia are on the brink of a major epidemic of the magnitude faced by sub-saharan Africa. This exceptionally rapid spread makes for a large infected but not yet actively sick population.
In the USA, approximately 1 million people received a blood transfusion annually with each person receiving an average of 2.9 units of blood. If these figures were applied to international travel, every two weeks 1.3 people in 10,000 would require blood. Where in countries such as Thailand where HIV is increasingly rapidly, the theoretical risk of transfusing blood from an HIV-seronegative but viraemic donor has increased greatly. In Chiang Mai (Thailand), the risk of receiving infected blood has been estimated at 1:200.

The association between travel and STDs has been known for centuries (particularly for syphilis), and it has been somewhat accurate to blame foreigners from sailing ships and armies. For example, Christopher Columbus's sailors allegedly brought syphilis to Europe, having acquired the infection during their first trip to America in 1492 after intercourse with Haitian women, and Captain James Cook was concerned with the spread of venereal disease, especially during his third voyage when almost half the ship's company were been infected prior to departure.

Accurate contact tracing is occasionally feasible; an often-quoted example is that of a Californian prostitute, nicknamed 'Syphilis Mary', who had secondary syphilis. She kept a diary which helped trace the activity of 168 long-distance truck drivers among her 310 'regulars' in 34 American states, Canada, and Mexico.

According to recent data, in England and Wales 14% of cases of early syphilis were contracted abroad. In Singapore, a country with a particularly robust reporting system, 88.9% of gonococcal infections in heterosexual men from 1991-1999 were acquired elsewhere in Asia. In Sydney, 64% of heterosexually acquired gonorrhoea in males from 1981-1989 was an Asian strain, of which half were acquired outside the country.

Rates of infection among prostitutes are a clear reason for the heterosexual transmission of HIV in any area in the world. Infection rates from 6-90% have been recorded among female prostitutes in urban areas of Africa and 3-60% in parts of Asia.

In two studies of businessmen being briefed before assignments abroad, there was mostly correct knowledge about general risk factors for AIDS, but only 25% requested more information though 30% did not know AIDS was present in the country they were visiting and only 10% said they would purchase condoms abroad. As above, an important conclusion emerged that has since been confirmed many times: despite adequate knowledge of STDs, many perceive no personal risk of disease transmission.

In Canada, as recently as 1991 14% of 331 business travellers did not think that avoiding sexual intercourse was protective, and many thought that condoms were more effective if used with fellow travellers than with locals.

In a study of Australians travelling to Southeast Asia, only 34% reported a definite intention not to have sex. Less than 60% of those who intended to have sex said they would use condoms 100% of the time. These travellers did not perceive a higher personal risk of acquiring AIDS in Asia than in Australia, even though they were aware of the magnitude of infection risk. Other studies have confirmed that while condoms are used by over 90% of travellers and workers some of the time, only about 50% use condoms all of the time.


  • You can virtually eliminate your risk of STDs or HIV infection if you avoid penetrative sexual intercourse with casual partners, especially intravenous-drug users and persons with multiple sexual partners (such as prostitutes).
  • If you practice sexual activity while in these regions, it is foolish, inconsiderate and dangerous to do so without a condom whatever type of sex (oral, vaginal, anal) is practised. And while you can reduce transmission risk by doing so, there is still the possibility of infection.
  • If you have been exposed to high-risk individuals such as prostitutes or practiced high-risk behaviours such as unprotected sex, post-travel tests for STDs are essential, even if you don't have symptoms. This is best done in a developed country at centres specialising in genitourinary medicine.

We trust this information will assist you in making correct choices regarding your health and welfare. However, it is not intended to be a substitute for personalized advice from your medical adviser.

Our appreciation to International SOS, an AEA Company who has contributed this article in response to a growing health threat faced by expatriates in Indonesia and Southeast Asia. Statistics show that 1 in 6 prostitutes in Thailand are infected with HIV. Closer to home, 3 out of every 1,000 expatriate men leave their assignment in Indonesia with HIV. The precautions suggested in this article are based on clinical experience.

If you have medical-related questions about living in Indonesia to ask of medical professionals, see Ask the Experts.