A vaccine, as an alternative method to prevent HIV infection, may still be many years away. This is partly because the virus mutates so rapidly. A vaccine may not only have to prime antibodies to attack the virus (the way most vaccines work) but might also need to increase T-cell production. Vaccine trials have been undertaken in South Africa, Kenya, the US and Thailand - though most have yet to yield promising results. Controversial vaccines made from the blood of HIV carriers, have been tested in Nigeria and Thailand.
There is no cure for AIDS, but a range of drugs - some of which have unpleasant side-effects - are available to slow its progress. Other drugs are used to treat opportunistic infections or AIDS symptoms. Even some herbal treatments have been investigated.
Most anti-HIV drugs aim at stalling viral replication. Nucleoside analogues such as AZT (zidovudine) and also non-nucleoside reverse transcriptase inhibitors (NNRTIs), attack the action of the viral enzyme reverse transcriptase. This prevents it from creating functional DNA which would otherwise integrate into the DNA of infected cells.
A third class block protease, an enzyme essential for generating functional virus particles. Protease inhibitors are the most effective of the three types of drugs, and AIDS mortality fell dramatically in the US when they were first licensed during the late 1990s. Fusion inhibitors are a newer type of drug that work by stopping HIV from binding with CD4 receptors that it uses to enter cells. Drugs that block another enzyme, integrase, are also under development.
AIDS drugs are often administered in combination cocktails cocktails of three or more kinds simultaneously, as this helps slow the rate at which HIV develops resistance to drugs. But the virus is able to evolve rapidly and can eventually outpace the drugs if treatment regimens are not followed rigorously.
Though drugs are widely available in western countries, their expense means they are unavailable to the vast majority of AIDS sufferers. International bodies are working towards widening access to treatment in the developing world. Some companies in countries such as India and Thailand are now producing cheap generic copies of drugs.
The economic and social burden of AIDS exerts a great toll on developing nations in addition to that exerted by mortality itself. AIDS is hindering development and leading to negative population growth in some of the most seriously affected nations, such as Botswana.
This excessive AIDS mortality is causing a great demographic shift, wiping out young adults in the prime of their lives. This leaves children orphaned, and is destroying workforces and economies. Some predict that 50 million children in Sub-Saharan Africa will have been orphaned by 2010. The labour forces of 38 AIDS ravaged countries will be up to 35% smaller by 2020, because of AIDS.
The effect of AIDS on agricultural communities in Southern Africa is even leading to food shortages. Social stigma and discrimination is yet another problem for many AIDS sufferers, especially in Asian nations.
If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.