LIZ’S husband works in a factory in Johannesburg and only comes home to their village at weekends. She has overheard him bragging about what he gets up to in the city, and she knows about the risk of AIDS. But he refuses to wear a condom when they have sex. He says it’s like eating a sweet with the wrapper still on – and besides, how would they have children? Liz is in no position to put her foot down because she is financially dependent on her husband. The last time she tried to insist, he gave her a black eye.

Liz is not one person. Her story is an amalgam of those of a great many women in the developing world. Some 5 million people became infected with HIV last year, most of them living in Sub-Saharan Africa. For people like Liz, the steps most Westerners can take to avoid this deadly infection simply don’t exist.

Ultimately, the best weapon against AIDS will be a vaccine. Finding one is the focus of intense research around the world, but we shouldn’t hold our breath. It could be many years before even a partially effective vaccine is ready, and the virus’s daunting molecular defences mean it is likely to be a lot longer before a highly effective vaccine is licensed.

In the meantime, scientists in several countries are investigating a completely different approach to AIDS prevention. It may not be as glamorous as vaccine research – it’s a relatively low-tech, hopefully low-cost strategy involving readily available chemicals. But it might be the developing world’s best short-term hope for curtailing this deadly pandemic. The aim is to develop vaginal medications, called microbicides or sometimes virucides, that stop the transmission of HIV during sex.

So far, efforts to bring the AIDS pandemic under control have focused on the "safer sex" approach, which implores people to use condoms and limit their sexual partners. If condoms are used correctly and consistently they offer good protection against HIV and other infections, and this approach is paying dividends in Thailand, Uganda and a few other developing countries. But the safer-sex message is not being heeded sufficiently in most of the regions where HIV is a major threat. Many people dislike interrupting sex to put on a condom, and the resulting reduced sensitivity. Condoms also raise questions of trust – some see a request for condom use as an admission or accusation of promiscuity. And condoms are, of course, contraceptive.

Condoms have another big drawback: their use requires the man’s agreement. In societies where women have little power they can find it impossible to get their partners to wear one.

Microbicides, on the other hand, would give women the option of taking action themselves, if necessary without their partners’ agreement or even knowledge. The aim is to devise products – gels, foams, creams, suppositories and impregnated sponges – that are largely undetectable, with no odour, colour or taste. Microbicides would not be a physical barrier that reduced pleasure – indeed, some products might even be promoted as "sex enhancers", emphasising positive attributes such as lubrication and perfume. It may also be possible to develop microbicides that are released from silicone rings that could be left in the vagina for several weeks or even months.

And microbicides don’t have to prevent conception – the aim is to develop both spermicidal and non-spermicidal versions. While the products would be used by women, they should also protect men against HIV infection. Many of the anti-HIV microbicides being investigated also destroy the organisms responsible for other sexually transmitted diseases such as gonorrhoea, chlamydia and genital herpes. And when possible they could be used along with condoms.

Significantly, the first products could reach the market within five or six years if any of several promising agents now poised to enter large-scale trials prove effective. About fifteen other chemicals are in early-stage human trials and some forty others are in preclinical studies. Many work in the test tube against a wide range of HIV strains from different continents. This is a huge benefit as it’s feared that vaccines will only work against the strains used to develop them or closely related ones.

Projections suggest that microbicides’ retail price in the developing world could be about <<<More>>>