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Scientists cautious despite strategy to fight human bird flu
Leigh Dayton, science writer
August 13, 2005
The good news on the bird flu front began about two weeks ago when two separate teams of international researchers reported in the journals Science and Nature that they'd simulated outbreaks of human bird flu with exciting results.
Both concluded that with fast action, targeted quarantine and up to three million doses of an anti-viral medication like oseltamivir, or Tamiflu, a pandemic of the potentially lethal strain of avian influenza, H5N1, could be slowed or even stopped.
Back then, a member of one of the teams - Elizabeth Halloran, of Emory University in Atlanta, Georgia - was hopeful: ?If, or more likely when, an outbreak occurs in humans, there is a chance of containing it and preventing a pandemic.?
Then this week there was more good news. French drug firm Sanofi-Aventis revealed results of a preliminary trial of a bird flu vaccine that showed their drug boosted immunity in 113 people. Plans are already on the drawing board to test the vaccine in a full study involving 450 subjects, the firm announced on Sunday.
Meanwhile, Australia's Melbourne-based CSL Ltd is also making progress on a protective vaccine. ?We're going into Phase One clinical trials, probably in October,? says CSL's spokeswoman Rachel David. ?(If all goes well) we could be fully ready to go (with a vaccine) within eight months.?
This all sounds very encouraging indeed. Yet even as experts like Australia's Alan Hampson welcome the good news, they add a bad-news caveat. ?It's a best-case scenario,? cautions Hampson, deputy director of the World Health Organisation's (WHO) Collaboration Centre for Influenza in Melbourne.
?If (an outbreak) happened in the back blocks of Cambodia or Laos, we'd be very fortunate to have it detected in time, diagnosed in time or have people on the ground in time,? he adds. In other words, smart tactics and effective drugs are not enough. They must be part of a rapid, concerted, national and international effort if an outbreak is to be contained.
And that's something scientists dearly want to do. While bird flu has so far killed less than 60 people in populous South-East Asia, epidemiologists fear it has the potential to become the Next Big One.
If bird flu develops the ability to be transmitted readily, person-to-person, it promises to follow the lethal lead of the three influenza pandemics of the last century. The worst was the 1918-1919 Spanish flu, which the WHO now estimates sickened roughly one-quarter of the world's population and killed almost 50 million people.
The nature of the bird flu virus reveals why experts worry that it has the hallmarks of a bug about to hit humans hard. For starters, it's a highly infectious form of influenza A that comes in several strains, including H5N1. Since bird flu was identified in Italy more than 100 years ago, it's spread widely in South-East Asia and is moving through Russia and Kazakhstan towards Europe.
Worryingly, avian influenzas like H5N1 can swap genetic material with flu bugs that infect other species, notably pigs and people. Hybrid viruses can sweep through so-called ?naive? populations with no natural immunity. Worse, pigs are susceptible to both bird and human flu, making them ideal ?mixing pots? for brewing novel super-bugs, both highly infectious and deadly.
It's little wonder that the WHO is racing to finalise a strategy for fighting outbreaks of human bird flu if - or when - they emerge. Central to the battle plan will be a global stockpile of anti-virals, preferably Tamiflu, considered most effective against H5N1.
But just as WHO officials are trying to nail down a deal with the manufacturer, Roche Products, 20 wealthy nations, including Australia, are snapping up supplies for their own stockpiles. Australia's deal with Roche remains confidential, but estimates are that the federal Government has contracted for $112 million worth of Tamiflu as part of its plan for managing an influenza pandemic.
As a close neighbour of the region most likely to suffer a dangerous outbreak, will Australia contribute stocks or hang on to them, preferring to fight an epidemic at home? ?Right now it's hypothetical,? says Health Minister Tony Abbott. ?It would depend on the circumstance at the time.?
And time is of the essence. Halloran and co agreed that to prevent the spread of disease, authorities must act within two or at most three weeks. Will evolving microbes leave time to find workable solutions? Only time will tell.