It was cynically known in the past as the silver lining for Africa in the AIDS disaster: the possibility that the toll from the spreading disease at least would mitigate the continent's other calamity, overpopulation.
But professionals gathered earlier this month in Dakar, Senegal, for the Sixth International Conference on AIDS in Africa say that even if population growth reverses--which is itself a heatedly disputed question--the pattern of deaths will inevitably spell further disaster for the continent. For new estimates indicate that AIDS is striking disproportionately at the most productive group, people between ages 15 and 49.
Experts say deaths in that age group will exacerbate the already troublesome imbalance between Africa's productive workers and its dependents, principally children and the elderly.
The fresh data is coming from one of the newest and most important areas of the study of AIDS in Africa: demographics. Researchers believe that studying the demographic impact is critical to understanding the potential cost of the epidemic. Their surveys go beyond the likely need for expenditures on health care--most estimates of which already exceed what anyone expects African countries will be able to afford--to predict the kinds of social and economic dislocations the plague may produce.
For all of that, health demographers say their conclusions are highly speculative and based mostly on computer models that try to predict how people will react to the multiple shocks of AIDS. Base figures are sketchy, where they exist at all. Many variables, including infection levels in most countries and even the incubation period between infection and appearance of the disease, can only be guessed at.
"These are really back-of-the-envelope calculations," said Martha Ainsworth, a health economist at the World Bank, "but they're the best we can do right now."
Even so, the future looks grim. "Even the optimistic scenarios are very depressing for Africa," said Roy Anderson, a professor of epidemiology at Imperial College of the University of London.
Current estimates from the U.N. World Health Organization are that 6 million Africans are infected with the human immunodeficiency virus, or HIV, which causes AIDS. That is 60% of the global total, and represents one of every 40 adult Africans.
By the year 2000, according to WHO projections, more than 14 million adult Africans will have been infected, and 4 million babies will have been born infected. By then Africa will have had 5 million people who have developed AIDS, or acquired immune deficiency syndrome.
Anderson's own studies, published recently in the British scientific journals Nature and the Lancet, suggest that in the most pessimistic scenarios involving very high rates of infection and spread, AIDS could cut the population of some heavily affected countries, particularly in East Africa, in half by the year 2040. This is unless a vaccine is developed and there is effective prevention, such as widespread use of condoms and changes in heterosexual behavior.
The population of sub-Saharan Africa is currently estimated at about 400 million, but the region has the highest birthrate in the world, growing at about 3% annually.
Anderson's conclusions have been widely questioned by other researchers who say that even their most pessimistic scenarios show the population growth rate diminishing, but not turning negative. This is because the basis of Africa's population growth is the high fertility rate of its women, who have an average of more than five children each.
"Even if all the women were infected with AIDS," said James Chin, chief epidemiologist for the World Health Organization's Global Program on AIDS, "they may not be infected until they're 25 or 30 years old, by which time a lot will have had one or two kids already. After infection, only 30-40% of their kids are born infected. That won't give you negative population growth."
Many experts are wary of the talk about negative population growth because they fear it may distract African governments from pursuing birth-control programs, which up to now have been considered crucial in extricating Africa from its economic abyss.
Some researchers even believe that AIDS may drive the rate of population growth higher, if Africans reacting to the fearsome toll begin to have more children, not fewer.
"It would be disastrous if this made governments downplay family planning," said Jeanette Murphy, a World Bank economist who has been surveying the impact of AIDS in Tanzania.
Regardless of their disagreement, Anderson and all other researchers believe that the pattern of AIDS deaths will leave fewer productive workers available to care for a higher ratio of children and elderly. At least one study predicts that the gross domestic product of some hard-hit African countries could be 20% lower than it would have been without AIDS.
More of that diminishing total may have to be diverted to health care, which now consumes only about 1% of the gross domestic product in many countries. Already 80% of the adult hospital beds in some cities are occupied by AIDS patients, and the disease has become the leading killer of adult men in many places.
A hint of what lies ahead can be glimpsed in Tanzania, one of the worst-hit countries and a place where the first empirical studies of AIDS' economic and development impact are being done.
In parts of Kagera province, which lies along the trucking route from the East African coast and where AIDS was first diagnosed in 1983, adult mortality rates are three times as high as they would have been were AIDS not present, according to a 1990 study.
One investigator has estimated that child mortality rates in the same region are already as much as 6% higher than they would have been without AIDS, and by 1999 may be as much as 43% higher--a rate that would more than wipe out all the gains of the last 10 or 20 years in reducing child mortality.
That does not even consider threats to children indirectly caused by AIDS, such as from the orphaning of otherwise healthy children. A 1989 census of Uganda's Rakai district, which adjoins Kagera and is one of the most heavily AIDS-ridden regions of Africa, found that nearly 13% of all children up to age 18 had lost at least one parent (the standard African definition of an orphan). While the survey did not determine how many were orphaned because of AIDS, other surveys show that the rate is roughly three times as high as the percentage of orphans in Ugandan villages that are relatively AIDS-free.
Researchers note that the impact of deaths from AIDS is almost certain to be far greater than that of death from other causes, such as accidents or diseases like malaria. By its nature, AIDS is more likely to kill both spouses in the same family. Traditional African strategies to handle adult deaths, including the remarriage of surviving spouses and the taking in of children by relatives, may be shunned out of fear that the survivors or children are infected.
Moreover, "AIDS doesn't spare the elite," says the World Bank's Ainsworth. On the contrary, in some parts of Africa, AIDS infection rates are higher among the more highly educated and in higher socioeconomic groups.
Because of its concentrated impact on productive adults, the social effects of AIDS in Africa are likely to be huge as farm families are decimated along with the civil service, medical professionals and teachers.
"You may get a change in crop mix, a threat to food security," said Ainsworth. "School enrollments will drop because children will stay home to care for their sick parents. But at the same time, there will be fewer teachers. It's a huge setback."