However, even given optimistic development projections, AIDS will continue to take a toll.
"As countries develop, they go through a transformation," lead researcher Colin Mathers, a statistician at the World Health Organization who specializes in global and regional health trends, told United Press International. "Along with development go improved living conditions, water sanitation and public health."
The seminal estimate of economic development's impact on future patterns of disease was made by Harvard University and WHO researchers in 1993 at the request of the World Bank. The data, though still widely cited, are somewhat incomplete and significantly underestimate the global effect of AIDS.
The updated version, which looks at three hypothetical scenarios of future global economic growth -- pessimistic, baseline and optimistic -- finds that in all three cases, the diseases of poverty recede to be replaced by diseases of increasing affluence.
Between 2002 and 2030 under all three scenarios life expectancy will increase around the world, and even the baseline scenario predicts 50 percent fewer children under the age of 5 will die.
If world economic growth is poor or moderate, by 2030 the three leading causes of illness will be AIDS, depression and heart disease, the study predicts. If economic growth is strong, road-traffic accidents -- a negative side effect of economic development -- will replace heart disease as the No. 3 killer.
The policy implications of these shifts are clear, Mathers said. Global health resources and research need to be directed to the diseases imposing the heaviest burden.
Efforts to prevent new HIV infections must be bolstered, in addition to gains that have been made in extending anti-retroviral treatment to those who already have the disease, he said. Assuming 80 percent of those in need of treatment receive it, global AIDS deaths are projected to reach 6.5 million by 2030 under the baseline growth scenario.
But more attention also needs to be paid to the future toll that increased tobacco use in the developing world will take, Mathers said. "Because people have taken up smoking relatively recently in the developing world, a lot of predicted mortality hasn't happened yet."
Tobacco-related deaths are predicted to rise from 5.4 million in 2004 to 6.4 million in 2015, when they will account for more than 10 percent of all deaths under the study's baseline scenario -- 50 percent more than AIDS. By 2030 tobacco-related illness is predicted to kill 8.3 million people worldwide.
The WHO has stepped up efforts to control tobacco use -- including talks on a global tobacco treaty -- but more needs to be done, Mathers said. "Some of the epidemic has already been fixed in by the smoking rate in 2002, but there's certain scope to address this problem."
Two other problems developing countries must now grapple with are things that are often not thought of as problems at all: eating more and living longer.
In many developing countries there are simultaneous struggles with famine and obesity, Mathers said, a "double disease burden."
Living longer means greater incidence of cancer, heart disease and stroke -- issues that must be faced, Mathers added. "It is important to draw attention to disease related to populations growing older in developing and developed countries."
The editors of the journal PLoS Medicine, where the WHO article appears this week, also questioned in a companion editorial whether medical research, which tends to focus on infectious disease, is being directed where it is most needed.
"We are indeed giving due attention to HIV/AIDS and to other infectious diseases," the editors write, "but we need to publish more research on cardiovascular disease, diabetes, mental health, road traffic accidents, and chronic obstructive pulmonary disease."
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