Pandemic risk rises as bird flu spreads, By Elisabeth Rosenthal and Donald G. McNeil Jr.
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But Africa also has the worst AIDS epidemic in the world; in some countries nearly a third of the adult population is infected. In the initial stages, having a depressed immune system could have a protective effect, said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, because virulent flus set off a powerful immune reaction that can drown the lungs in fluid.

However, he added, it would probably hurt patients trying to fight off secondary immune reactions.

But HIV-infected people who managed to fight off bird flu would become ideal crucibles in which the H5N1 virus could exchange genes with other viruses, dramatically increasing the likelihood of a bird flu strain that could readily infect humans.

"If H5N1 gets into people with AIDS it would likely persist and throw off mutants left, right and center," Oxford said.

If bird flu takes root in Africa - or if has already done so, undetected - it could prove disastrous not just for that continent, but for Europe as well, experts say, since the northern migration of birds begins next month.

"The prospects are not good," said Oxford. "Soon they'll be coming back over Europe and why wouldn't it cause a great danger?" As a virologist, Oxford said that he could only assume that Nigeria was just the "red light we could see," but that there were similar bird flu problems in many other places.
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With little accurate information about the disease's spread, scientists have been left to speculate about the possible impact of the disease in Africa.

Population density is lower than in Asia, Heymann noted, which could slow the spread. "Flu could wipe out all the chickens in a village, but there's still savannah or jungle between the villages," he said. Also, living with birds under the same roof is somewhat less common than in As