# 2998
From the very first known human infections from the H5N1 virus it has exhibited a high mortality rate. In Hong Kong, in 1997, 6 of the 18 people infected died.
Since it re-emerged in 2003, the global CFR (Case Fatality Ratio) has run about 60%. In Indonesia, where good medical care is less readily available, the fatality rate has run well over 80%
Egypt has always been a bit of an exception.
Even before this year, the CFR in Egypt had been about 45%. Horrific, yes - considering this is an influenza strain - but almost half that of Indonesia.
With a dozen non-fatal cases during the first 3 months of this year, the CFR in Egypt has now dropped to 36%. And that’s when you average over 3 years.
This year, not only have all 12 cases survived, most have exhibited relatively mild symptoms.
Something has changed in Egypt with the virus. Exactly what that `something’ is, however, isn’t clear.
But it does have scientists worried.
It has long been assumed that, in order for the H5N1 virus to become a pandemic strain, it would have to give up some of its virulence. That a virus that produced severe, rapidly fatal symptoms would have difficulty spreading.
Now, at least in Egypt, we are seeing what appears to be a lessening of the H5N1 virus’s virulence. This attenuation of the virus doesn’t necessary mean the virus has become more transmissible.
But even if it hasn’t as yet, a milder virus is better positioned to evolve into a more transmissible strain.
Milder cases are less likely to seek medical treatment, and are more likely to be dismissed as seasonal flu when they do. That gives those infected more opportunities to spread the virus to others, and they in turn can spread it even further.
Each new human infection gives the virus another opportunity to mutate into a more human-adapted virus, another roll of the genetic dice
The more human cases, the more chances the virus has to mutate into a pandemic strain.
This from The Independent.
New bird flu cases suggest the danger of pandemic is rising
Infections in Egypt raise scientists' fears that virus will be spread by humans
By Geoffrey Lean, Environment Editor
Sunday, 12 April 2009
First the good news: bird flu is becoming less deadly. Now the bad: scientists fear that this is the very thing that could make the virus more able to cause a pandemic that would kill hundreds of millions of people.
This paradox – emerging from Egypt, the most recent epicentre of the disease – threatens to increase the disease's ability to spread from person to person by helping it achieve the crucial mutation in the virus which could turn it into the greatest plague to hit Britain since the Black Death. Last year the Government identified the bird-flu virus, codenamed H5N1, as the biggest threat facing the country – with the potential to kill up to 750,000 Britons.
<SNIP>
The WHO fears that this year's rise in infections among small children, without similar cases being seen in older people, raises questions about whether adults are being infected but not falling ill, so acting as symptomless carriers of the disease. Its investigation, due to start this summer, will see if this is happening by testing the blood of people who may have been in contact with infected birds, but who have not themselves become sick.
<SNIP>
Professor Robert Webster, of St Jude Children's Research Hospital in Memphis, Tennessee – who is the world's leading authority on the disease – told The Independent on Sunday that, while he himself had not seen firm data, the WHO in Egypt was raising "a very, very important issue" which should receive "maximum attention". He added: "I hope to hell they are wrong. If this damn thing becomes less pathogenic, it will become more transmissible."
