Keywords:

Acquired Immunodeficiency Syndrome (AIDS); bridging population; commercial sex worker; HIV prevention and control strategies

Idea:

Acquired Immunodeficiency Syndrome (AIDS) was first recognized in 1983 when scientists had no clue what the cause of AIDS was. Two years later the etiologic virus, Human Immunodeficiency Virus (HIV), was subsequently identified. HIV/AIDS began spreading into Southeast Asia only a few years after it was first described in the USA. However, the pattern for the predominant mode of transmission was and still is somewhat different from the West. Whilst HIV has been spreading in Europe and North America mostly among men who have had sex with other men (MSM), the virus is being effectively transmitted via heterosexual transmissions in Thailand and her neighboring countries. Although the Thai virus was once reported to have more efficiency in heterosexual transmission in vitro, there is no proof whether this enhanced efficiency can explain preferential heterosexual transmission in Thailand and other countries in mainland Southeast Asia (Indochina, Myanmar, and Malaysia). This article discusses the innovation shift in HIV/AIDS prevention and treatment, with special reference to the bridging population of commercial sex workers (CSW).

Scenario:

In fact, bridging populations such as commercial sex workers (CSW), either male or female, may have played an essential role in shaping predominantly the heterosexual HIV epidemic in Thailand and other Southeast Asian countries (Figure 1). Information on these relationships is particularly useful for the good design of HIV prevention/control strategies.

Demand for unconventional preventive measures:

Strategies for prevention of HIV transmission through sexual routes include behavior modification, safe sex practice, condom use, microbicide gel, circumcision, post-exposure HIV prophylaxis, and more recently pre-exposure HIV prophylaxis. A blood screening policy has been in place for more than 25 years and hence there is now effective prevention of HIV transmission through blood transfusion. Prevention of HIV infection in children born to HIV-infected mothers, using cocktail of anti-HIV drugs, has led to an ultra-low incidence of HIV acquisition in the new born. Whilst prevention of HIV transmission in blood/blood product recipients and in babies born to HIV-infected mother has been hugely successful, prevention strategies for reducing its sexual transmission are still tricky. In some countries, for instance Thailand, campaigns and free condom distribution has led to the control of HIV transmission to a plateau level, but the prevalence and new infection rate is still high (Fig 2). Interventions to further reduce the occurrence of new infections are still on the loose.

Perhaps conventional prevention measures of sexually transmitted diseases (STD) per se are not sufficient to prevent against HIV transmission.

An alternative strategy-immunization by vaccine: a medical service innovation?

The quantity of HIV (HIV load) is known to be a key factor for the successful transmission. Treatment of HIV/AIDS by anti-HIV drugs leads to a significant reduction in the HIV load, and hence decreases the probability of HIV transmission to uninfected sexual partners. In theory, if the virus load of all HIV-infected persons is fully suppressed by anti-HIV drugs, their partners are very unlikely to contract HIV from them.

Despite several billions of dollars in global investment and some 25 years in the quest for a safe and effective HIV vaccine, we have observed only one successful, though marginally successful, story. The level of protection in vaccinated persons is only slightly more than 30 percent above that of non-vaccinated subjects.

There may be a light at the end of the tunnel, even after Merck’s HIV trial failed to improve the efficacy a few years ago. While we are waiting for a more effective HIV vaccine, other interventions are indispensible for slowing down the epidemic, particularly in the young. We still do not know how long this diminuendo of the HIV epidemic will go on, but hopefully the epidemic will not begin a new crescendo in a new risk group.

Implications:

• A combination prevention strategy should no longer be limited to a campaign, education and condom use program anymore. Newer interventions such as circumcision, prophylaxis by anti-HIV drugs, and early HIV treatment may need to be included and discussions amongst policy makers, clinicians, scientists and HIV activists are urgently needed in order to reach more effective control of HIV transmission.
• However, a treat-all strategy may not be realistic due to the expense, particularly for developing countries, as well as the adverse side-effects of the anti-HIV drugs. Successful stories from combating other viruses would suggest for us an alternative strategy: immunization by vaccine.

Early Indicators:

• Education, behavior modification sessions and HIV/AIDS campaigns have long been operating in all countries, but we are still observing approximately 2.7 million new cases a year (UNAIDS/WHO).
• The number of HIV/AIDS patients and those who likely died of AIDS has been decreasing; patients live longer and have better quality of life. As a result, AIDS patients and deaths from AIDS have dropped by more than in the past through better treatment and innovation of health services.

Drivers & Inhibitors:

Drivers:

• An increase in the regional HIV infection rates, and the number of infections per day amongst the younger generation, are indicators of the re-emergence of the problem.
• Regional progress in the development of HIV/AIDS vaccines and drugs could help reduce the spread of the virus.
• An increase of international philanthropic and inter-governmental funding for HIV/AIDS prevention and research programs has occurred.
• The frequency of multiple sexual interactions and sexual abuse could change the equation.

Inhibitors:

• Continued disapproval of contraception, and condom use in particular, on religious or cultural grounds, and by the younger generation.
• Superstitions and urban legends about HIV infection persist.
• Uncertainty on funding for HIV/AIDS prevention and treatment programs from the government in Southeast Asia.
• Malpractice from alternative medicine and patient misbehavior.
• A strong social stigma against those with HIV/AIDS prevents some from seeking effective treatment.
• A lack of political support for new more effective control measures.