About 2.6 million people worldwide will die of AIDS this year, the most of any year since the epidemic began, according to a report by the United Nations AIDS program.

The estimate means roughly one in every 20 deaths on the globe is now caused by AIDS, a disease unknown two decades ago. About 16.3 million people have already died of AIDS.

In addition, about 5.6 million new infections with the human immunodeficiency virus (HIV) will occur this year, raising the number of people currently living with the disease to about 33.6 million.

"HIV continues to spread nearly unabated in many parts of the world," said Peter Piot, director of UNAIDS, an organization run by the United Nations, the World Health Organization, the World Bank and several other agencies.

The UNAIDS "epidemic update" was released yesterday in preparation for the 12th annual World AIDS Day, which is Dec. 1.

UNAIDS epidemiologists now believe that in sub-Saharan Africa, the home of 70 percent of people with HIV, more women than men are infected. (The ratio is about 12 women to every 10 men, according to the report.) This marks the reversal of a trend.

Early in the epidemic, a relatively small number of female prostitutes infected many men. Over time, the gender gap closed. Now, women predominate, as infected men transmit the virus to their wives and noncommercial sex partners.

Girls age 15 to 19 are five times as likely to become infected as boys in the same age group--a fact that reflects both biological and social realities. Male-to-female transmission of the virus occurs more easily than female-to-male transmission. Teenage girls often have sexual contact with older men, who are more likely to be infected than teenage boys.

"One implication [of the current ratio] is that, paradoxically, we probably need to target men far more in our prevention efforts," Piot said. "We need to start with educating boys . . . and see if we can do anything with men who are already adults."

Piot said the data will probably also add urgency to finding methods of protection that women can control. These include the female condom, which he said is too expensive for most users, and vaginal microbiocides, which are not yet perfected.

Among the groups in which infection is rising steeply are drug users in countries of the former Soviet Union. In the Russian Federation, for example, half the cases reported since the epidemic's start were reported in the first nine months of this year alone. Although both past and current numbers are gross underestimates, UNAIDS researchers believe they point to a real trend.

Because of its small population and comparative wealth, the Caribbean has been an overlooked area of HIV growth, Piot said. However, among UNAIDS's official regions, the HIV prevalence there--about 2 percent--is second only to Africa's.

This year's estimate for India--about 4 million people infected--is actually smaller than last year's because of better data. There and in China, which has 500,000 cases, the epidemic is in an early stage. Both countries have such huge populations, however, that they will largely determine what happens worldwide in the next two decades.

Piot said predictions done in the 1980s overestimated the number of infections in Western nations, while the African experience has turned out to be worse than anticipated.

The current HIV prevalence in sub-Saharan Africa--8 percent of adults for the region, and up to 30 percent in some cities--is "unbelievably high," said Bernhard Schwartlander, UNAIDS's chief epidemiologist.

"We get used to it . . . but if you said several years ago that it would go that high, no epidemiologist would have believed it," he said. It is not likely to get much higher, he added.

There were encouraging findings in the report, as well.

Thailand's model HIV prevention campaign seems to have weathered the Asian financial crisis, with the rate of new infections staying low. The epidemic is being contained, as well, in the Philippines, in part because of registration and biweekly health screenings of prostitutes. The reluctance of some political leaders to confront AIDS is fading in many places.

"Everywhere I go, I hear African leaders say that HIV and AIDS are the biggest obstacle to development and economic change. . . . That is a welcome statement," Piot said.

The State of AIDS Around the World

Despite new treatments and information campaigns, HIV infection and AIDS are growing rapidly around the world.

Of the 33.6 million adults & children with HIV/AIDS, the newly infected account for nearly 17%.

Sub-Saharan Africa

Epidemic started: late '70s

Adults & children living with HIV/AIDS: 23.3 million

Adults & children newly infected: 3.8 million

Adult prevalence rate: 8.00%

Percent of HIV-positive adults who are women: 55

Main modes of transmission*: Hetero

North Africa & Middle East

Epidemic started: late '80s

Adults & children living with HIV/AIDS: 220,000

Adults & children newly infected: 19,000

Adult prevalence rate: 0.13

Percent of HIV-positive adults who are women: 20

Main modes of transmission*: IDU, Hetero

South & Southeast Asia

Epidemic started: late '80s

Adults & children living with HIV/AIDS: 6 million

Adults & children newly infected: 1.3 million

Adult prevalence rate: 0.69

Percent of HIV-positive adults who are women: 30

Main modes of transmission*: Hetero

East Asia & Pacific

Epidemic started: late '80s

Adults & children living with HIV/AIDS: 530,000

Adults & children newly infected: 120,000

Adult prevalence rate: 0.07

Percent of HIV-positive adults who are women: 15

Main modes of transmission*: DU, Hetero, MSM

Latin America

Epidemic started: late '70s

Adults & children living with HIV/AIDS: 1.3 million

Adults & children newly infected: 150,000

Adult prevalence rate: 0.57

Percent of HIV-positive adults who are women: 20

Main modes of transmission*: MSM, IDU, Hetero

Caribbean

Epidemic started: late '70s

Adults & children living with HIV/AIDS: 360,000

Adults & children newly infected: 57,000

Adult prevalence rate: 1.96

Percent of HIV-positive adults who are women: 35

Main modes of transmission*: Hetero, MSM

Eastern Europe & Central Asia

Epidemic started: early '90s

Adults & children living with HIV/AIDS: 360,000

Adults & children newly infected: 95,000

Adult prevalence rate: 0.14

Percent of HIV-positive adults who are women: 20

Main modes of transmission*: IDU, MSM

Western Europe

Epidemic started: late '70s

Adults & children living with HIV/AIDS: 520,000

Adults & children newly infected: 30,000

Adult prevalence rate: 0.25

Percent of HIV-positive adults who are women: 20

Main modes of transmission*: MSM, IDU

North America

Epidemic started: late '70s

Adults & children living with HIV/AIDS: 920,000

Adults & children newly infected: 44,000

Adult prevalence rate: 0.56

Percent of HIV-positive adults who are women: 20

Main modes of transmission*: MSM, IDU, Hetero

Australia & New Zealand

Epidemic started: late '70s

Adults & children living with HIV/AIDS: 12,000

Adults & children newly infected: 500

Adult prevalence rate: 0.10

Percent of HIV-positive adults who are women: 10

Main modes of transmission*: MSM, IDU

TOTAL

Adults & children living with HIV/AIDS: 33.6 million

Adults & children newly infected: 5.6 million

Adult prevalence rate: 1.10%

Percent of HIV-positive adults who are women: 46

*MSM=Male to male sexual transmission, IDU=Injected drug use, Hetero=Heterosexual transmission

SOURCE: UNAIDS