Bird flu is more virulent, lethal, not good if it became communicable between humans.
A couple small corrections:
* The death of a medical worker in China has prompted concern that the avian flu virus can spread between humans.
It was not that one death that prompted concern. Such concerns existed for a long time, and they were initially prompted by observations of close structural similarity of the binding sites of avian and human haemagglutinin. Much clamour arose in 2012 when Ron Fouchier’s lab in Rotterdam identified five mutations that make H5N1 aerosol-transmissible in ferrets (and by implication, in humans). Pushing the work to publication was quite an effort; they had to overcome public hostility, resistance from NIH (the funding source for this research), NSA, and America’s then-favourite non-sectretary of state, among many other impediments. Last year, two of these mutations were found in chickens on a farm in Egypt. Hostilities continue:
* Two types of bird flu have been identified to date: H5N1 and H7N9
There are two errors is this statement. One is that both H5 and and H7 have nine neuraminidase subtypes. It would be less incorrect if the statement only mentioned “H5 and H7″. Then, there are actually three H-types of avian influenza A in wide circulation in Eurasia: H5, H7, and H9. The H9 type does not get as much attention as the other two because it has not been documented as highly pathogenic, but it is under surveillance, and the Chinese are very concerned about it:
Sound like a virologist, Gene. Thanks for the expanded commentary.
Clearly you have special knowledge or one helluva talent for learning what’s important in an exotic area of medical inquiry. I like it.
However, I would point out that these bird to people things have not panned out in the past, and there has been plenty of opportunity.
So we will have to be aware and alert and I still have my concerns that public health people thrive on panics and so, every year, there is a new scare.
In fact, we haven’t seen anything of import in many years now. You could say, give credit to vaccines. I would prefer to argue fer than agin.
I would say the new criteria for “epidemic” lowers the threshold and I am not sure of the benefit, other than public health people get more publicity and mic time.
Not a virologist myself; I just happen to share office space with a bunch of really good ones, so can’t help picking random bits from them.
Your statement about these bird to people things that have not panned out in the past probably refers to H5N1, which is just one of many possible bird to people things with a limited history of surveillance. It did not pan out because so far it has only been transmissible by direct contact. But we know (thanks to EMC) what it needs to become aerosol-transmissible — just a few substitutions around the HA binding site. It is already deadly to humans, just not easily enough transmissible to pan out.
What did pan out big time was the virus that caused the 1918 pandemic. It was both deadly and transmissible, and it most certainly originated in birds (the 1918 flu genome was recovered, so we know what it was and can compare). Presently, all known variants of influenza A circulate in wild waterfowl — pick any you want.
Even common cold is a recently adapted bird virus.
Epidemic is not a precise notion; there are no threshold criteria for what to call an epidemic. I think people working in flu surveillance call an epidemic when they note a few dozen isolates of the same virus collected by a regional lab in a short time — say, within a month.
But there are well-defined criteria for treating an outbreak seriously. A serious treatment involving a global response and new vaccines is required when the new virus represents a significant antigenic change compared to the previously circulating seasonal flu. This paper explains the idea (see the first image for a quick overview):
Even more reasons for concern if a novel virus crops up all over the world. It is easy to understand the panic of 2009, especially at the onset, when it was recognised as a variant of the 1918 pandemic but nobody knew whether it would make a similar impact. At the epicentre, it did look just as scary.
Thanks for the excellent commentary. Yessiree the commonality on the 1918 strain H5N1 did make the red flags go up.
And I never had an inclination to raise chickens–they attract varmints and I have had too many dogs that killed too many neighbor chickens to deal with deaths in my own family. I have 3 dogs so that means no chickens. I don’t fancy any chicken slaughtering at my place.
I used to have Great Danes and at one time had two wonderful Dalmatians. They were not easy on chickens.
Sadly, once a dog has eaten a chicken you just have to get rid of it. I don’t know why, but sometimes they get along just fine with each other. Out of half a dozen dogs I had at the same time I had chickens only one ever got a taste for them. Keeping birds is a pain, but once you’ve gotten used to what REAL free range eggs are like, it’s hard to go back to store-bought.
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