ENEVA, Nov. 24 — An estimated 5.3 million people, including 600,000 children under age 15, became infected with the virus that causes AIDS this year, the World Health Organization said today.

For the first time the number of new infections in sub-Saharan Africa stabilized, but that was offset by increases in morbidity (the rate the disease was contracted) and deaths in the region.

An estimated 3.8 million people in the region were newly infected this year with H.I.V., the virus that causes AIDS, down from 4 million in 1999. Sub-Saharan Africa is home to about one-tenth of the world's population but accounted for 72 percent of new infections last year. The region also has 70 percent of the people living with the virus or with AIDS, and 80 percent of the deaths in the past year, according to the health agency's Weekly Epidemiological Record.

Worldwide, 36.1 million adults and children are estimated to be living with AIDS or the virus, split almost equally between men and women.

In the two decades since the disease was recognized, it has killed an estimated 21.8 million people, including 3 million this year. The numbers of women dying continue to increase, accounting for an estimated 52 percent of adult deaths this year, the health agency said.

The disease claims new victims in all parts of the world, including industrial countries, although the availability of therapy is slowing progression from viral infection to AIDS and death, the agency said.

Over all, the number of new viral infections in industrial countries "has remained relatively constant over the past few years," it said, citing data that showed the United States and Canada had an estimated 920,000 people living with the virus or with AIDS, with approximately 45,000 new cases this year.

Another 540,000 victims live in Western Europe, which had about 30,000 new infections this year. Australia and New Zealand have an estimated 15,000 infected people, and about 500 new infections this year.

People who inject drugs were responsible for most of the new infections in Eastern Europe and Central Asia, the report said. These areas suffered some of "the sharpest increases in H.I.V. infections," with an estimated 250,000 people newly infected this year, leading to a 60 percent rise in the regional total of people living with the disease, to 700,000.

Asia and the Pacific countries are second only to sub-Saharan Africa in the number of people, estimated at 6.4 million, living with the virus or with AIDS. This included more than 900,000 new cases this year, the report noted. The new cases were attributed largely to the sex trade and illicit drugs.

North Africa and the Middle East had an estimated 80,000 new cases this year, bringing the regional total of infections to 400,000.

Latin America and the Caribbean have a total of 1.8 million people with H.I.V. Some countries are experiencing increased heterosexual transmission, but in others, infections "remain concentrated mainly in men who have unprotected sex with other men and injecting drug users," the agency said.

Transmission in sub-Saharan Africa remains primarily by heterosexual contact, and 25.3 million of the total number of living victims live there. The Ivory Coast, Kenya, Tanzania, Uganda and Zimbabwe have reported the highest number of cumulative cases on the continent.

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