The global AIDS epidemic spread at an alarming pace last year with a record 4.8 million new infections, according to a U.N. report released Tuesday, which expressed concern that the virus is spreading quickly in Eastern Europe and Asia.

Issued in advance of the 15th International AIDS Conference, which opens Sunday in Bangkok, the report said that governments were not doing enough to prevent the spread of AIDS. Only one in five people worldwide have access to prevention programs, it said.

Sub-Saharan Africa continued to have the world's highest incidence of AIDS, the report said. But Eastern Europe and Central Asia are suffering from the fastest rate of growth in HIV infections, U.N. officials said. HIV is the virus that causes AIDS.

In Asia, prevention has been inadequate "partly because of stigma and discrimination," the report said. There were success stories in Thailand and Cambodia, where prevention programs deal more openly with high-risk behavior, such as intravenous drug use and prostitution, said the U.N. report, which warned against "complacency."

"What's happening in Asia is determining the global outcome," Peter Piot, executive director of the Joint United Nations Program on HIV/AIDS, said in a telephone interview. "There is a desperate need for leadership, particularly in Asia and in Eastern Europe."

Thirty-eight million people worldwide were estimated to have HIV last year, 3 million more than at the end of 2001, the U.N. report said. It said that comparing the latest estimates with those published in previous years was "misleading" because the new figures had been revised downward based on "improved methodologies."

More than 20 million people with the disease have died since the first AIDS diagnosis in 1981.

The epidemic's spread throughout the world continued to be alarming, with about 9 million new infections since the last two-year reporting period, the report said.

In Eastern Europe and Central Asia, injected drug use is the major reason for new infections. But sub-Saharan Africa, where about 25 million people have HIV, remains the region hardest hit by the epidemic.

Life-prolonging drugs were not reaching enough patients in developing countries, where only about 7 percent of those who need treatment receive it, the U.N. report said.

HIV antiretroviral drugs are available to most of the estimated 1.6 million infected people in so-called high-income countries, including the United States. There were 950,000 people with HIV in the United States at the end of last year, 50,000 more than in 2001, the report said.

While the AIDS epidemic initially affected mostly men, the U.N. report said recent surveys showed that nearly half of all people infected between the ages of 15 and 49 were women. In Africa, more than half were women.

The increasing vulnerability of women makes it difficult to impose abstinence and condom use as strategies to prevent AIDS, Kathleen Cravero, the program's deputy executive director, said at a news conference.

"Most of the women and girls, as much in Asia as in Africa, don't have the option to abstain when they want to," she said. "Women who are victims of violence are in no position to negotiate anything, never mind faithfulness and condom use."

In Asia, with 60 percent of the world's population, 7.4 million people are living with HIV. The epidemic is fueled by injected drug use, infected sex workers and sex between men, but it is fast moving into the general population, the report said.

China and India have severe epidemics in a number of provinces, territories and states, the report said. In Indonesia and Vietnam, infections among people who inject drugs have soared.

"There's a window of opportunity to get prevention programs up to scale in Asia," said Cravero. "If we miss it, we will see an epidemic the likes of which we never imagined."

Far from leveling off, infection rates are on the rise in many countries in sub-Saharan Africa. In that region alone last year, 3 million people became newly infected with HIV. In seven African countries -- Botswana, Swaziland, Lesotho, Zimbabwe, South Africa, Namibia and Zambia -- more than 15 percent of the population is infected.

Latin America continued to have low national rates, but there were serious local epidemics, again spurred by people who shoot drugs and by men who have sex with other men, Cravero said.

In the Caribbean, which has the highest incidence of AIDS outside sub-Saharan Africa, the epidemic is spreading most rapidly among heterosexuals.

In high-income countries such as the United States, experts are concerned about the resurgence of sexually transmitted infections and high-risk behaviors, such as having unprotected sex. "People are dropping their guard and that will have its consequences," Cravero said.

More people were also dying from AIDS-related illnesses, the report said. In 2001, 2.5 million people died from AIDS. Last year, 2.9 million died, the result of rising caseloads outstripping countries' abilities to provide treatment, U.N. experts said.

Improved data-gathering methods at the country level have resulted in a revised, lower estimate of the number of people with HIV, Cravero said. Two years ago, the last time the report was issued, the United Nations estimated that 40 million people had HIV.

"Whether it's 38 million or 48 million, it's a catastrophe that has to be dealt with," she said.

The report comes as the world has boosted its commitment and resources, but not enough to meet growing needs, the U.N. report said.

In recent years, countries and donor organizations have stepped up their contributions to combat AIDS, from $300 million in 1996 to about $4.7 billion last year. But this amount was still less than half of the $12 billion required for 2005, the report said.

"AIDS is likely to be with us for a very long time, but how far it spreads and how much damage it does is entirely up to us," said Piot, the program executive director.

In Thailand, an AIDS patient is kept isolated at a hospice in a provincial temple, about 100 miles north of Bangkok. An HIV-positive infant is cared for at the Phyathai Babies Home, an orphanage in Bangkok. The U.N. report praised Thailand and Cambodia for slowing the rate of new infections through preventive programs but warned against complacency.