VIENNA - The world will face a mighty social and medical challenge as millions of people with HIV survive into old age, the world Aids forum has heard.

The problem is only now becoming apparent as the first generation living with HIV head towards their 60th birthday and beyond, thanks to the lifeline of antiretroviral drugs, specialists say.

These survivors are mainly in western nations, where the precious therapy first became available from 1996. But they will soon be followed by millions of counterparts in sub-Saharan Africa and other poor countries where the drug roll-out started in the middle of the last decade.

That these people should have stayed the course is itself a stunning testimony to ARV's - and, say some of the survivors themselves, something of a miracle.

"We lived from day to day," Jean-Luc Romero, 51, a councillor for the Paris region said as he recalled the situation in 1987, when he learned of his HIV status.

"There was no point planning beyond that. We saw people dying all around us and we didn't think about the future. I thought I wouldn't live beyond 30."

Aids first came to light in 1981. Before antiretroviral treatment developed, people usually progressed to the disease within a decade after infection by HIV and died a year or two afterwards.

For many of those now advancing into old age, living with HIV will be fraught with medical problems, loneliness, stigma and worries about finance, a seminar at the 18th International Aids conference heard this week.

"There have always been older people with HIV, but what is new is the numbers. That will require new public health thinking compared to the past," Gottfried Hirnschall, director of HIV-Aids at the UN's World Health Organisation, said.

"Ageing with HIV is not just a clinical challenge, but also a social challenge and it's not just confined to one part of the world versus another," he said.