Asia's largest AIDS conference opens on Sunday as research shows that the disease is spreading faster there than anywhere else in the world.

Most HIV-positive patients live in Africa, but the signs are that Asia could eventually rival it, or even surpass its total.

The Fifth International Congress on AIDS in Asia and the Pacific, being held in the capital of Malaysia, Kuala Lumpur, this week, will focus world attention on the issue.

An estimated 3,000 experts, campaigners and patients are expected to attend.

Marina Mahathir, president of the Malaysian AIDS Council, is chairing the conference.

"In the last year, at least half of the new cases worldwide came from South and Southeast Asia. The trend is upwards and that's worrying," she says.

Most HIV spread in Asia is caused by heterosexual sex and by injected drugs, although every country has different circumstances.

There are an estimated five to seven million HIV infected people in Asia.

One in 20 infected

In developing countries such as Cambodia, already ravaged by war in recent years, an estimated 5% of the population is infected.

In India, the authorities have been criticised for underestimating the problem - it is thought there are four million infected, which is more than any other single country in the world.

A Cambodian AIDS orphan

In Thailand, the first Asian country to be heavily affected, about 2% of the population is infected, a figure fuelled in part by the sex industry.

Much of the conference will focus on overcoming religious and cultural taboos that make safe sex education difficult in many countries.

Massive prevention campaigns, which have proved relatively successful in Western European and North American countries, may prove extremely difficult to replicate in Asia.

Mahathir said: "A lot of our societies are very conservative and would rather not talk about it. Denial is a very major problem."

Few countries have escaped the HIV/AIDS problem.

Remote problem

In the remote country of Nepal, the virus has been spread by the trafficking of girls to Indian brothels, the large number of migrant workers, a rise in urban prostitution in Nepal itself, and primitive blood banks, which lack any of the usual screening technology to root out blood from infected donors.

The "Westernisation" of China has encouraged widespread movement of people for the first time in recent years.

This, according to the World Bank, provides the conditions necessary for the spread of HIV.

Sexually transmitted diseases of all sorts, which were virtually eradicated from China in the 1960s, are now rising rapidly.

The World Bank report says: "Despite some bright spots on the map in terms of effective government and non-government action, without further interventions targeted at the populations at risk - such as sex workers, homosexuals and injecting drug-users - the epidemic in these countries hold s the potential to dwarf the health crisis through which Sub-Saharan Africa has suffered for the past decade."

African horror

AIDS has now become the leading cause of premature death in some African countries.

It has killed millions and left millions of children orphaned, a legacy which will haunt governments economically and socially for decades.

The development of AIDS following HIV infection is swift in people whose general health is not good, or whose nutrition is poor.

And even if the patient has the advantage of good health, the expensive anti-viral therapies used in Western countries are simply not affordable in most cases.

Even treatments which can greatly lessen the chances of mother-to-child transmission are too expensive. Another topic under discussion at the conference will be the prospects for an affordable HIV vaccine which can be used in developing countries.