HIV TAKING HUGE TOLL IN AFRICA.

Byline: Lawrence K. Altman The New York Times

In certain areas of Africa, one in four adults is infected with the virus that causes AIDS, and around the world the disease now rivals the greatest epidemics of history, according to a United Nations report issued today.

In the first country-by-country analysis of the disease, the United Nations said that last year 30 million people worldwide were infected with HIV, the AIDS virus, and that 21 million were in Africa.

Countries south of the Sahara account for the world's 21 highest rates of HIV among adults 15 to 49 years old, the most sexually active segment of the population. In 13 of those countries, HIV has infected at least 10 percent of adults, and in Botswana and Zimbabwe, a quarter of adults are infected, a rate that even an expert described as ``shocking.''

The report, released ahead of the 12th international AIDS conference that will begin here Sunday, paints the gloomiest pictures of the HIV epidemic since it was first recognized in 1981.

AIDS is hitting Africa so fiercely that it now rivals the great epidemics of history - the Black Death of the Middle Ages that killed 20 million people, or one-quarter of Europe's population, in four years and the influenza pandemic of 1918-19 that killed 20 million people, including half a million Americans.

But where plague and influenza killed in days, death from untreated AIDS takes about a decade, making it a more silent epidemic that officials have too easily ignored, officials noted.

``If HIV killed as rapidly as plague and influenza, the epidemic would be controlled by now,'' Dr. Peter Piot, the head of the U.N. AIDS program, said in an interview.

The report contained a glimmer of good news, showing a slowing of infection rates in countries that have adopted strong prevention programs, like Senegal, Tanzania, Thailand and Uganda.

But Piot and other officials warned that South Africa, Namibia and other African countries soon could reach a 25 percent adult infection rate unless national leaders undertake similar programs.

Infection rates exceed one in three adults in some major African cities and reach 70 percent of women tested in some prenatal clinics. Many infected women pass the virus on to their babies.

The overwhelming majority of the Africans are doomed to die from AIDS, the officials said, because they live in countries that cannot afford the costly combinations of drugs that have helped keep the virus in check among infected people in developed countries.

The African figures compare to a worldwide adult HIV-infection rate of 1 percent for adults and 0.76 percent in the United States. Moreover, officials said, 90 percent of the African patients probably do not know they are infected because testing is not widely available.

Worldwide last year, 5.6 million people were newly infected while 2.3 million died from AIDS. AIDS is now on the verge of moving into the top-five leading causes of death in the world, overtaking diarrheal diseases. The viral infection now kills as many people as malaria and is second only to tuberculosis, which itself is a common complication of AIDS.