Johannesburg, South Africa ? It began innocuously, when a statistical anomaly pointed to a mysterious syndrome that attacked the immune systems of gay men in California. No one imagined 25 years ago that AIDS would become the deadliest epidemic in history.

Since June 5, 1981, HIV, the virus that causes AIDS, has killed more than 25 million people, infected 40 million others and left a legacy of unspeakable loss, hardship, fear and despair.

Its spread was hastened by ignorance, prejudice, denial and the freedoms of the sexual revolution. Along the way from oddity to pandemic, AIDS changed they way people live and love.

Slowed but unchecked, the epidemic’s relentless march has established footholds in the world’s most populous countries. Advances in medicine and prevention that have made the disease manageable in the developed world haven’t reach the rest.

In the worst case, sub-Saharan Africa, it has been devastating. And the next 25 years of AIDS promise to be deadlier than the first.

AIDS could kill 31 million people in India and 18 million in China by 2025, according to projections by U.N. population researchers. By then in Africa, where the virus has wrought the most devastation, researchers said the toll could reach 100 million.

Children eat their porridge at an orphanage in Blantyre, Malawi. One of the biggest problems facing the poverty-stricken African country is the growing number of children who lose their parents and guardians to the AIDS epidemic.

“It is the worst and deadliest epidemic that humankind has ever experienced,” said Mark Stirling, the director of East and Southern Africa for UNAIDS.

More effective medicines, better access to treatment and improved prevention in the last few years have started to lower the grim projections. But even if new infections stopped immediately, additional African deaths alone would exceed 40 million, Stirling said.

“We will be grappling with AIDS for the next 10, 20, 30, 50 years,” he said.

Uneven efforts

Efforts to find an effective vaccine have failed dismally so far. The International AIDS Vaccine Initiative says 30 are being tested in small-scale trials. More money and more efforts are being poured into prevention campaigns, but the efforts are uneven. Success varies widely from region to region, country to country.

Globally, just 1 in 5 HIV patients get the drugs they need, according to a recent report by UNAIDS, the body leading the worldwide battle against the disease.

Almost two-thirds of those infected with HIV live in sub-Saharan Africa where poverty, ignorance and negligent political leadership extended the epidemic’s reach and hindered efforts to contain it. In South Africa, the president once questioned the link between HIV and AIDS and the health minister urged use of garlic and the African potato to fight AIDS, instead of effective treatments.

In at least seven countries, the U.N. estimates that AIDS has reduced life expectancy to 40 years or less. In Botswana, which has the world’s highest infection rate, a child born today can expect to live less than 30 years.

“Particularly in southern Africa we may have to apply a new notion, and that is of ‘underdeveloping’ nations. These are nations which, because of the AIDS epidemic, are going backward,” Peter Piot, the director of UNAIDS, said in a speech in March.

Fueling the famine

Besides the personal suffering of the infected and their families, the epidemic already has had devastating consequences for African education systems, industry, agriculture and economies in general. The impact is magnified because AIDS weakens and kills many young adults, people in their most productive years.

So many farmers and farmworkers have died of AIDS that the U.N. has invented the term “new variant famine.” It means that because of AIDS, the continent will experience persistent famine for generations instead of the usual cycles of hunger tied to variable weather.