- An outbreak of flu in rural south-east Asia could spread
around the globe in three months and infect half the world's population
within a year, unless strict measures to contain it are introduced, scientists
- The warning comes from researchers who used computer
models to investigate what would happen if the avian flu virus, which is
currently rife among poultry in areas of China, Cambodia, Thailand and
Vietnam, mutated into a form that spread easily among humans.
- Scientists believe it is only a matter of time before
the virus, known as H5N1, mutates to become more infectious to humans,
possibly by swapping genes with the human flu virus.
- "This is the event we're all scared might happen
at any time," said Neil Ferguson of Imperial College London and the
leading author of the study. "We'd be faced with an event worse than
the 1918 Spanish flu pandemic."
- The avian flu virus has killed more than 50 people in
Asia, more than half of those who have been infected. Almost every death
was traced back to the person coming into contact with infected poultry
in the countryside. The Spanish pandemic of 1918 is believed to have claimed
up to 40 million lives worldwide.
- Professor Ferguson's team modelled the spread of a mutated
avian flu virus among 85 million people living in Thailand and a strip
of neighbouring countries. After watching how quickly the virus spread
around the globe, they tested various strategies for containing an outbreak.
"Until now, the idea of stopping an outbreak hadn't been investigated,"
- If an outbreak was detected in its infancy, with less
than 50 people infected, models show it could be contained by administering
antiviral drugs to the 20,000 people closest to those infected, the researchers
report in the journal Nature today. Combined with other measures, such
as shutting schools and workplaces, it would take around 60 days to contain
the outbreak, with the number of cases totalling no more than around 200.
- To deal with the worst case scenario of an avian flu
outbreak, the scientists called for an international stockpile of 3m courses
of antiviral drugs to be set up, ready to be deployed anywhere in the world
within a few days of an outbreak being detected.
- A spokeswoman for Roche, which manufactures the antiviral
drug Tamiflu, confirmed that the company is in talks with the World Health
Organisation about building a stockpile of the drug, but refused to give
further details. The WHO already has 120,000 courses of Tamiflu, but with
Britain and France each waiting for orders of 15m courses from Roche, the
company will have to decide which takes priority.
- Prof Ferguson's research is reported alongside a second
study published online today by the US journal Science, which modelled
an outbreak of flu among half a million people living in Thailand.
- Ira Longini and his team at Emory University in Atlanta
also found that antiviral drugs could be used to contain an outbreak by
giving them to healthy people closest to those infected. Flu vaccines,
even relatively poor ones, would also help quash a nascent outbreak, he
- According to Professor Longini's model, 100,000 courses
of Tamiflu would be enough to prevent a flu outbreak becoming a pandemic
as long as the virus had a "reproductive number" - the average
number of people each infected person goes on to infect - of no more than
1.6. Measles, one of the most infectious diseases has a reproductive number
of around 15. Typically, each person infected with flu infects two others.
- Prof Longini said the creation of an international stockpile
of drugs should take precedence over orders from individual countries.
"The WHO should get priority ... and the richer nations should chip
in, because it's in their interests to stop it before it reaches their
shores," he said.
- Creation of the stockpile is just the first hurdle. The
WHO, in conjunction with the US Centres for Disease Control and Prevention
in Atlanta, will have to tread carefully with governments to ensure the
policies are adopted and that outbreaks are spotted quickly enough.
- A scientist close to the programme said: "The big
issue is surveillance. If these models are right, and there may be problems
with them, the outcome depends on getting an early warning of an outbreak."
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