A world congress on Aids gets underway on Sunday amid what appears to be a lull in the war against the disease and an emerging challenge to cherished strategies.

Around 22 000 activists, scientists and policymakers are expected in Mexico City for the six-day International Aids Conference, the 17th in the series and the first in Latin America.

The biennial meeting coincides with a new UN assessment that, after claiming more than 25 million lives in 27 years and leaving another 33 million people infected with HIV, the Aids pandemic is at last stabilising.

Infection rates are rising in many countries

The tally of new infections is still edging up and some countries remain in Aids' steely grip, but prevalence of the disease, as a percentage of the global population, has reached a plateau, says the agency UNAids.

Aids deaths in 2007 fell to some two million, a 10-percent fall over two years. Nearly three million poor, badly-infected people now have access to the wonder drugs that have transformed the human immunodeficiency virus from a death sentence to a manageable disease.

Despite this achievement, experts are grim.

Many say infection rates are rising in many countries. Some predict the treatment question which dogged debate for a decade will return once the wily virus mutates. And all caution that only a vaccine or a cure can stop the pandemic — and both lie beyond the far horizon.

"We still don't completely understand the various forms of the virus. It's more complicated for us than we thought," says France's Luc Montagnier who with Robert Gallo of the United States identified HIV as the cause of Aids.

Can the world afford to save people's lives?

In 2007, around $10-billion in funds were allocated to fighting HIV/Aids in developing countries. It helped 2.9 million people gain access to antiretrovirals, or 31 percent of the people who need it.

To achieve just 80 percent of the UN's goal of universal access by 2010 will require $42.2-billion, or more than four times all of the spending in 2007, according to UNAids calculations.

"The massive influx of dollars is not keeping up with the pace of the HIV/Aids epidemic," the US journal Science noted last week.

The arithmetic poses a nightmarish dilemma: Can the world afford — or be willing to pay — to continue saving people's lives?

Against this backdrop of entrenched problems, time-honoured methodologies are now being questioned.

Elizabeth Pisani, a US-born epidemiologist, ruffled feathers this year with a book, "The Wisdom of Whores," that said scare-mongering and political correctness had wasted resources and failed to tackle nodes of infectivity, thus helping HIV's spread. Pisani told AFP that HIV/Aids was not a menace that weighed on all countries and on all individuals equally.

The writing is on the wall

The truth is that a generalised risk — i.e. to the population as a whole — prevails only in a relatively small, badly-hit group of countries in sub-Saharan Africa, she said.

In the rest of the world, the risk comes from niche groups — gays, drug users, sex workers and people who have multiple sex partners and have recently become infected and thus have more virus.

But targeting efforts specifically at these groups has been hampered by activists, who say this will worsen stigma for people who already suffer discrimination, argues Pisani.

UNAids itself has come under fire.

To critics, the agency inflated the scale of the pandemic — it has repeatedly downgraded its estimates as better data became available — and the result has been to drain funds from other diseases that are just as lethal but lack celebrity backers.

"The writing is on the wall for UNAids," Roger England of Health Systems Workshop, an independent advisory agency, wrote in the British Medical Journal (BMJ) in May. "Why a UN agency for HIV and not for pneumonia or diabetes, which both kill more people?"

Pedro Kahn, president of the International Aids Society (IAS) which is hosting the upcoming conference, said Aids had to be treated as an exceptional disease — not just because of the virus' extraordinary stealth, but for the way it flourished in taboo, ignorance and stigma.

"Almost 7000 people are still contracting HIV every day. In some countries, Aids is the main killer," said Kahn.

"So what should we do? Should we stop funding the fight against HIV in order to put this money into other areas? We are really confronting a new disaster (that has emerged) in the last 25 years and we need to have the funds for that."

AFP