A brief history of the deadly virus

MUMBAI: Virologists are hitting the panic button. The H5N1 virus that causes the now ubiquitous Bird Flu holds enormous potential to morph into a pandemic. If it does, researchers at the Lowe Institute for International Policy, an independent Sydney-based think tank reckon it can kill as many as 142.2 million people across the world by the end of this year.Of these numbers, 12.1 million could be Indian and 14.2 Chinese.
The H5N1 virus has a long history of being vicious. In 1918, an earlier variant called the H1N1 killed 40 million people. Historians recorded it as the Spanish Flu. Just when everybody thought the H1N1 was extinct, it finds itself in the news again. Late last year, Science published the genetic sequences that make up this virus. It caused an outrage in academic circles because leading scientists reckoned this information could be used by terrorists to create an artificial strain and unleash biological warfare.
The virus struck again in 1957. This time around, it had mutated into H2N2. More popularly called the Asian flu, it wasn���t as deadly as the H1N1. Estimates of the casualties it triggered varies between 1 to 4 million people. A decade later, an eerily similar variant called the H3N2 or the Hong Kong flu emerged to claim 7.5 lakh people.
Intermittently, other variations of the virus appeared in other parts of the world. Much of it only infected poultry. The flu these viruses caused couldn���t transmit to humans and the matter ended there. Very rarely though, these viruses mutate and acquire the ability to move from birds to humans. H5N1, reportedly, acquired this capability as early as 1997.
That was when Hong Kong reported the new virus, how it infected 18 people and caused 6 deaths. They followed it up by culling 1.5 million birds and catastrophe was averted. The virus stayed dormant for a while, but reared its head again in 2003. Since then, over 200 million birds have been slaughtered. But it hasn���t prevented humans dying recently in countries all the way from Asia to Europe.
In much the same way that bird flu exists, humans have human flu. When both strains meet, they mutate further and creates something that can move rapidly from one human to another. Then there is the very nature of the virus. Research published in the latest issue of the Proceedings of the National Academy of Sciences says at least four different gene families of the virus exist.
For pharmaceutical companies hoping to come up with a vaccine for H5N1, this is bad news. Their work will now have to focus on a vaccine that deals with this diversity. For a sense of how urgently the world needs a vaccine, consider this. The Spanish Flu of 1918 had a mortality rate of 2.5%. H5N1, currently, has a mortality rate of 50%. Until the vaccine comes, there is no way out, but to slaughter the birds.