Scientists and doctors the world over are bracing themselves for a possible flu outbreak which could quickly kill millions.
"At the moment this is the theoretical risk, but there are warning signs that this outbreak could occur," he says.
Since mid-December 2003, a growing number of Asian countries have reported outbreaks of the highly pathogenic avian influenza in chickens and ducks.
Infections in several species of wild birds and in pigs have also been reported.
Scientists now fear that this avian influenza, which has infected humans in South East Asia, could mutate to allow the virus to be transmitted from human to human.
Scientists know that avian and human influenza viruses can exchange genes when a person is simultaneously infected with viruses from both species.
If the new virus contains enough human genes, transmission directly from one person to another (instead of from birds to humans) could occur.
This was the situation during the great influenza pandemic of 1918-1919, when a completely new virus sub-type emerged and spread around the globe in less than six months.
Professor Barry Schoub, the director of the National Institute of Communicable Diseases, says there have been two cases in Thailand where the avian flu virus was transferred between humans.
If the avian flu mutates we will experience a pandemic."
But Schoub says South Africans are not immediately at risk as avian flu has not been detected in this country.
"If pandemics do come in regular cycles, then it appears we are due for one now," he explains.
Experts at the World Health Organisation (WHO) estimate that if there is a pandemic it could kill from 2-million to more than 50-million people across the globe.
Schoub says South Africa is examining its current preparedness plans and is part of the WHO programme.