"You don't have export poultry industries in Africa near the scale of what you see in Asia," Morrison said. South Africa is the main exception, he added.
If the virus reaches Ethiopia, Kenya, or Nigeria, he said, "there will be minor culling required. If it hits Congo, it's not going to be necessary."
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The impact of the H5N1 strain on human health in Africa is uncertain. According to Morrison, there are "inadequate volumes of [the flu-fighting drug] Tamiflu, inadequate volumes of vaccine, and no one really knows how to use either of them [against bird flu].
"That's a global problem, and it's going to be seen even more acutely in Africa."
So far nearly all human cases of avian flu have resulted from direct contact with infected birds. But with each person or animal it infects, the virus gets another shot at a terrifying jackpot.
A random genetic mutation during viral replication could make the pathogen transmissible from one person to another, triggering a global flu pandemic on the scale of the infamous "Spanish flu," which killed tens of millions in 1918 and 1919.
Yet the relatively small number of farmed poultry in Africa could minimize the odds of the virus mutating there.
"Asia will remain the genetic roulette table for influenza virus," said Michael Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
According to avian expert Gary Allport of Birdlife International, the UN agriculture organization may have overstated the immediacy of the risk that migratory birds pose to Africa.
Of the migrating species that penetrate deep into Africa, few come in close contact with people or domestic fowl.
Mallard ducks are the most significant cause for concern, Allport said. They're known to carry H5N1, and they do associate with domesticated and semi-domesticated birds. Many mallard flocks spend the winter in the Nile Delta and elsewhere in North Africa.
Fortunately, Allport said, "they don't venture much further south, certainly not in huge numbers."
The regions at greatest peril, he said, "will be North Africa and maybe the western border of the Red Sea [in] Egypt, Sudan, Eritrea, and Ethiopia."
"The way to reduce risk is to manage the domesticated birds carefully," Allport said. That includes keeping poultry away from wild species that could harbor the virus.
It also means restricting trade of live birds that could pick up the virus during transport. Since last week's ominous UN announcement, several African countries have taken steps to curb imports of potentially infected fowl.
The first case of bird flu in Britain, reported last week, occured in a parrot that "almost certainly picked it up" at or on its way to Heathrow Airport, when it came in contact with a shipment of birds from Taiwan, Allport said.
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