Not To Be Sneezed At
By Mark Honigsbaum
17 October, 2005
The GuardianHow scary is bird flu? Is it, as Mike Davis, the author of The Monster at Our Door, puts it, a "viral asteroid on a collision course with humanity"? Or are the it's-not-if-but-when predictions overblown?
Yesterday the chief medical officer, Sir Liam Donaldson, said that the strain of bird flu might not hit Britain this winter, but that it would reach these shores sometime soon. Having stood in the same ward as a Vietnamese man with bird flu in February, and having just visited Ceamurlia de Jos, site of the latest outbreak in Romania, I think Sir Liam's cautious warning is justified. H5N1 - or GenZ as the current superstrain is called - really is a monster of a virus. Chickens infected with GenZ don't just die, they melt, leaching blood from every organ.
In people, the pathology has not been anything like so extreme. But flu textbooks say humans shouldn't be able to be catch an avian virus such as H5N1 at all - at least not before it has infected an intermediary animal. Moreover, while about 100 people worldwide have contracted GenZ since it first emerged in Hong Kong in 1997, 60 of them have died - a worryingly high mortality rate.
That's not all. Intensive chicken farming, combined with fast-rising south-east Asian populations and international jet travel, has created what one epidemiologist calls a "perfect virological storm".What could this mean for you or me? A few weeks ago, David Nabarro, the UN's influenza coordinator, came up with a global death toll of 150 million. The World Health Organisation quickly offered a rebuttal, saying the correct figure was 2 to 7.4 million. But as the WHO well knows, the only true predictor is what happened in 1918. Then, as now, an avian virus suddenly acquired the ability to latch on to and invade human lung cells. The difference is that the Spanish flu - so-called because Spain was the only country not to censor news of the illness - was also highly infectious between humans. Scientists now estimate that the 1918 pandemic may have killed 40 to 100 million people worldwide. If you take into account the current world population, a direct extrapolation gives you 325 million deaths.
If that's not sufficiently scary, there's more. Epidemiologists estimate the 1918 virus killed 2.5% of those infected. But we know that GenZ kills 70% of the people it infects. In other words, the true worst-case scenario based on 1918 could be 1 billion deaths worldwide. This is what Davis means by the monster at our door and why he believes scientists, and the press, are right to sound the alarm.
Then again, it may never happen. Flu is one of the deadliest pathogens in nature's arsenal, but is also one of the sloppiest. Like all viruses, every time it replicates it makes mistakes, some of which may render it less infective. That is the conundrum of H5N1. It could be a huge threat to the human race or none at all.
Moreover, just as global trade now threatens to bring the virus to Europe, so better surveillance by the WHO and World Animal Health Organisation means we know the instant a Romanian or Turkish chicken falls ill. It may make for lurid reading, but in the case of H5N1, forewarned is forearmed.
Finally, politicians are belatedly listening. George Bush's reading list this summer included John Barry's The Great Influenza, the authoritative work on the 1918 pandemic. And in the wake of Hurricane Katrina, he has followed the lead of other governments by increasing stockpiles of Tamiflu, an anti-retroviral drug unavailable in 1918.
So be afraid, but remember that no one understands H5N1 well enough to say what will happen. And, fingers crossed, it never may.
· Mark Honigsbaum is the author of The Fever Trail: In Search of the Cure for Malaria
