A new report shows that the global AIDS pandemic will cause a sharp drop in life expectancy in dozens of countries, in some cases declines of almost three decades. The International AIDS Conference in Barcelona, several nations are losing a century of progress in extending the length of life.

A U.S. Census Bureau study released at the conference reveals that nations in every part of the world, 51 in all, are suffering declining life expectancies because of an increasing prevalence of HIV infection.

The impact is in Asia, Latin America and the Caribbean, but is greatest in sub-Saharan Africa, a region with only 10 percent of the world's population but 70 percent of its HIV infections.

The author of the U.S. Census report, Karen Stanecki, says some developing countries are avoiding the slide, but most are not. "Currently we have seen success, declines in prevalence only in a few areas," she said. "But in most other countries, prevalence has remained high or is increasing. As a result, in the next 10 to 15 years, we are going to continue to see major impacts on populations."

Seven African countries have life expectancies of less than 40 years. For example, in Botswana, where 39 percent of the adult population is infected with HIV, life expectancy is 39 years. But by 2010, it will be less than 27 years. Without AIDS, it would have been 74 years. The U.S. report predicts a similar outcome for Mozambique, while projections for life expectancies in South Africa, Swaziland, Angola, Lesotho, Namibia and Rwanda range from 33 to just under 37 years.

"By 2010, less than 10 years from now, we project that life expectancies are going to be back to levels that were not seen since the late 19th century for these most severely affected countries," she said.

The U.S. figures also show that life expectancies throughout the Caribbean and some Central American nations will drop into the 60s by 2010 when they would otherwise been in the 70s without AIDS. In Cambodia and Burma, they are predicted to decline to around 60 years old from what would have been in the mid-60s.

Even in countries where the number of new infections is dropping, such as Thailand, Uganda and Senegal, the U.S. report predicts small life expectancy drops.

Ms. Stanecki says another result of the AIDS pandemic is a loss of population in the hardest hit African countries where there are more deaths than births.

"Back in the early 1990s, we never would have suspected that population growth would have turned negative because of AIDS mortality. In less than 10 years, we expect that five countries will be experiencing negative population growth because of AIDS mortality, including South Africa, Mozambique, Lesotho, Botswana and Swaziland," she said.

The U.S. Census study also points out that AIDS is boosting infant mortality rates, again mainly in Africa. This is reversing a decline occurring in the 1980s and early 1990s. Although overall global rates are expected to decline by 2010, there will be more infant deaths than if AIDS had never developed.

The Assistant Administrator for Global Health at the U.S. Agency for International Development, Anne Peterson, calls the trends outlined in the study staggering. "What are we going to do so that the projections beyond 2010 do not continue to escalate? This is a call to action to make a difference," she said.

The U.N. AIDS Program says $10 billion is needed to slow the HIV pandemic, but has commitments of less than one-third of that amount from the affected nations, donor countries, and multilateral agencies.