By Elizabeth Blunt
African countries are stepping up measures at ports and airports to detect travellers who might be carrying the Sars virus.
This follows warnings that the pneumonia-like disease poses a particular threat to people whose immune systems have been weakened by Aids.
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So far the continent has not been affected by Sars, although one suspected case is being investigated in South Africa.
But with Sars continuing to spread in East Asia, African countries are gradually waking up to the threat they could face.
Kenya, Uganda and Ethiopia are now checking all travellers from affected areas, and health authorities from Lagos to Cape Town have been put on alert.
There may be no confirmed cases in Africa yet, but the possibilities are frightening.
One of the scientists who discovered the Aids virus, Luc Montagnier, warned this week that people whose immune systems were already weakened by Aids would be very vulnerable to catching Sars, and if they caught it, would be much more likely to die.
If Sars and Aids combine, said Professor Montagnier, it would be a disaster.
In some parts of Africa more than a third of adults carry the Aids infection.
Uganda's government-owned New Vision newspaper has warned that because of this Sars could strike with lethal speed and has called for a massive public education campaign.
Some people would go further; in South Africa a researcher in the field of public health is fighting a one-man campaign to get South Africa Airways to stop all flights to Hong Kong, so as to at least delay the spread of the virus to what he says is a critically vulnerable population.