Bird Flu Mania

[Firbolg]

Could this be the big one that all the experts keep warning us about? The UN now says it could kill 150 million.. some 'experts' say as much as a billion.. some just a 'few' million.. last I heard the current strain is very lethal but not very infectious among humans so doesn't seem much of a problem *yet*.

They keep comparing it to the 1918 spanish flu but I would like to think modern medicine has progressed a fair but since then so should be able to deal with such an event before it gets out of control.. but who knows..

Is it time to stock up on duct tape and tinned food?

Will it be all talk and no action?

On the plus side it could solve the worlds population problem for a while!

Gotta love the internets ability to stir up a global panic about something that hasn't happened yet and may never happen!

[plumflower_pm]

There has historically been disasters and illnesses that kept the human population in check. As far as I know, we're way way overdue. However as you pointed out, modern medicine may keep pandemics in check that 150 years ago would have wiped out continents full of people.

It's sad that we won't keep our own population levels down without assistance from natural disasters.

[zachsan]

i haven't heard anything about this. when you say "a billion"... are you talking about humans or birds? cuz you know, in the case of humans, that's a sixth of our population.

which kinda makes me think that i would have heard about this.

[mortal]

Are you sure I thought I heard china had 4 billion. The rest of the world would only be another 2 billion. I think it is more.

[zachsan]

well you're right, china does not have twice the population of the rest of the world combined. it's got a lot of people, but not that many. i might be wrong, but i believe china and india have around 2 or 2 1/2 billion between them, which is still an absurd percentage.

from the CIA World Factbook:
China - Population: 1,306,313,812 (July 2005 est.)
India - Population: 1,080,264,388 (July 2005 est.)

yep, so between China and India, 2.4 billion. and that's a CIA World Fact. book.

[plumflower_pm]

I think he maybe meant "billion" in the 'kazillion' sense. Or perhps the 'majillion' sense.

[Firbolg]

The billion figure was in some report I read somewhere and is (hopefully) highly unlikely.. 150 million was the figure given by some UN panel the other day.. I think they guestimate based on how lethal it is - currently more than 50% of people infected die.. however since its not very infectious yet its 'lethality' is not that big a deal yet.. question is if it mutates again and becomes highly infectious will it at the same time become less lethal? Read somewhere something to that effect.. I think the big killer flu strains of the past were not as lethal, they were just very infectious so the end result is more people dead.

I presume if/when it does make the leap it will be the poorer countries with big populations that suffer most.. but then again with frequent/fast air travel these days it could easily hit everywhere very quickly.

[Firbolg]

btw you can see how hot a topic it is on the net these days by searching boardtracker..

http://www.boardtracker.com/search/?search=bird+flu&cat=1&for=0&order=0&scope=4&filter=1

and of course google news..

http://news.google.com/news?sourceid=mozclient&ie=UTF-8&oe=utf-8&hl=en&edition=&q=bird+flu

[zachsan]

The World Health Organization moved Friday to dampen fears over alarming predictions quoted by one of its own officials that a pandemic stemming from the bird flu virus ravaging parts of Asia could kill as many as 150 million people.

oh, haha! it's just in Asia! LOL, why didn't you say that to begin with? you had me scared for a minute there!!

[Firbolg]

oh, haha! it's just in Asia! LOL, why didn't you say that to begin with? you had me scared for a minute there!!

lol, thats harsh man..

[Shaolin Science]

Part of the problem with this is that it is now infecting migratory birds not just chickens and farm fowl. If the migratory birds are infected they can fly well outwith Asia and then it's pandemic time. Course the problem only arises if the virus mutates to some super infectious form, so lets keep the fingers crossed that it doesn't. And as far as modern medicine is concerned there still isn't a cure for regular flu and for a virus which already has a high mutation rate even if a cure was found it's possible that the virus will have mutated around it by the time we get use it.

Still might as well enjoy life for now

R

[LeiYunFat]

It's duck huntin' season

[doc]

Well, since I'm now struggling with the flu, after my arrival from Thailand into the US, I find this an interesting thing to discuss.

"Bird flu" is kind of a misnomer, for, technically, all the "flu's" in this virus category technically have some connection with birds, and birds of different species, both wild, domestic, and kitchen table prepared. There are three major types of viruses, A, B, and C.

Types

The A viruses have as their source of activity, both the human, animal kingdom and the avian populations. There are many subtypes of these A viruses, some that only infect the varoius avian species, and some that have crossed over to also infect the human population. A viruses have been responsible for some serious epidemics and pandemics in the past, including the Hong Kong flu of 1968 and the Asian flu of 1957. The huge 1918 Spanish flu, which killed hundreds of thousands across the globe, was also an A virus.

B viruse typically only infect humans; they are viruses which the human species have more experience with, and therefore, more immunity (as opposed to the A viruses, which humans might have had no previous exposure to, thus no immunity or ability to fight the virus, which leads to the virus' ability to wreak massive devastation). B viruses are involved with our typical flu sypmtoms.

C viruses can cause mild illnesses in humans, and generally, are not too significant.

Viruses are subtyped according to the type of two proteins that are found on their outer shell; the hemagglutinin and neuraminadase proteins, which are denoted respectivefully as HA and NA, or, as H and N. There are 15 different types of H proteins, and 9 different types of N proteins, that are found. Different viruses have different combinations of these two H and N proteins; also, not all combinations (currently) have infectious potential.

A virus is just a strand of genetic material that is covered in a protein sheath. The protein sheath has an H and an N protein, which the body uses to identify it. If the body has been infected with a virus before, it recognizes the H and N proteins, and generates its immune response to attack and destroy these viruses before they can infect cells and do damage. If the body does not recognize the H and N proteins, then the virus can enter the animal's cells, take over the cells manufacturing processes, cause the cell to generate new virus material, all of which causes the cell to eventually die, occasionaly, by the process of swelling and rupturing. The combination of the H and N protein is referred to as the antigen. If the human has been exposed to this antigen before, it recognizes it, and eventually, fights it. If the human has not been exposed to this antigen before, it has to recognize it as "evil", and generate an immune response to it, manufacturing antibodies that can seek out and destroy the viral invader. A virus such as the HIV virus that causes AIDS is a tough one, because the virus hides within human cells for a while, without triggering an antigenic response.

Drift and Shift

Now, the problem is, viruses don't keep this all that simple. They change, they evolve, they "mutate".

The proteins on the surface can change slightly, as the infection through the population proceeds, to the point where a human, who might have been infected with virus A H1 N1, and who fights the infection easily, and subsequently develops immunity to it (because he now has the proper antibodies to fight this virus), can, later on in the epidemic (an infection in a community of people), develop a subsequent infection to the "same" virus, because its proteins have altered a bit: A H1a N1. The individual's immune system recognizes this new strain of virus because it is similar to a previous infection, and therefore generates a rapid response to fight off the new strain. How successful the response is all depends upon how good the person's antibodies are in recognizing and destroying the new strain. We call this antigenic drift; minor changes in the virus' protein coat, kind of like a "disguise", can lead to reinfection with a previously fought virus.

Antigenic shift is when the virus's protein coat undergoes major changes, such as when virus A H3 N3, previously only found as an infectious agent in birds, for example, chckens, undergoes mutation, and then becomes A H3 N4, which can infect chickens and wild fowl. The virus can then readily transmit outside of it's local original community, thus leading to a possible pandemic into other communities throughout the world. Another antigenic shift occurs when A H3 N4 turns into A H3a N4a, which can now infect wild fowl and humans. The problem is, humans might have seen infection before with various A Hx Nx viruses, but never before with a A H3 N4 type of virus, as it was never infectious in the human population (only the chicken population). Now, a variant of that original virus is floating around, and it can invade human tissue. Because there is no prior "experience" with this virus in the human population, there is no immune response, and no immediate recognition or "fight" against this viral invader. We call these major changes in viral coat protein makeup, antigenic shift.

I've "made up" the above numbers purely for demonstrative purposes. Technically, there are fifteen different H proteins as I've said before, but the H5, 7, and 9 tend to be the ones associated with potential human infection. As there are nine N proteins, there are nine potential subtypes of each of these H forms. H7 forms are usually only found in people that have close contact with infected fowl, and these infections tend to be limited both in infection rate and in severity of symptoms. H9 infections are rare, and tend to be not highly pathogenic. H5 infections have occurred in humans before, and they tend to be highly virulent and destructive.

The 1918 pandemic was caused by an A H1 virus that underwent antigenic shift. No one really knows where this A virus orignated from, but it was estimated that it had undergone antigenic shift about ten times, as it changed from its original "human non-infectious" form, to its human infectious form. As the human population had no previous experience with this brand of virus, it had a devastating effect on the population.

The current "Bird flu"

The current one that is of concern, A H5 N1, is of a highly virulent H5 subtype, that previously was only infectious in chickens. It has undergone antigenic shift to the point where it now not only can infect wild fowl, but also can infect humans. The problem with this virus now, and the reason why it is triggering so much concern, is because of the following two reasons:

One: The virus, unlike previous respiratory viruses that get "trapped" in the nasal cavity and sinues, upper airway, and subsequently, bronchi and bronchioles, triggering nasal congestion, bronchitis, cough, bronchial swelling, etc, for some reason, bypasses these structures and proceeds all the way down to the final unit of the lungs, the air sacs themselves, the alveoli. The alveoli are small air sacs which are surrounded by pulmonary capillaries; this is where gas exchange between the air and the blood stream take place. The A H5 N1 virus attacks the alveolar cells directly, causing them to swell and explode, thus leading to a virtual destruction of the lungs. For this reason, the death rate can be over fifty percent. This is not your typical flu by any means.

Two: The 1918 virus that triggered the world wide pandemic, though not really known where it originated from, was generally felt to have undergone antigenic shift about TEN times, before it became wildly infectious with the human population. The virus changed that significantly, and was that different, that the human population had virtually no previous experience with it. Thus, it was incredibly devastating. Now, in 1918, there was not worldwide transport system in place like we have now; nowadays, a virus could enter a plane in a host, and end up in another part of the world in a matter of hours. The transmission of a virus of this nature, throughout the world, could virtually take one day. A frightening prospect indeed.

The other frightening prospect, is the potential use of A H5 N1 as a bio terrorist weapon. Once this virus undergoes significant antigenic shift, and becomes a real threat to the human population, its use as a weapon is horrifying, to say the least.

The scary thing about A H5 N1, at this point in time, is that it has undergone antigenic shift FIVE times already.

Treatment

A virus types tend to be sensitive to the usual antiviral medications, however, this new A H5N1 seems to be resistant to the usual antiviral mainstays in current medicine, amantidine and rimantidine. Oseltamivir (Tamiflu) seems to be one of the few antiviral medications that we currently have available, that still seems to be effective in treating the A H5N1 virus, which is why, there is currently a buying spree of this medication in the various pharmacies throughout the US. It has to be taken very early during the initial infection for it to be effective.

Having been a survivor of the SARS epidemic in Asia, and, having been a frequent visitor to Asia (and, also having seen many of these people virtually living with their chickens), I find all of this interesting, and, to some degree, a bit disconcerting. The whole concept of having chickens living outside your door, living in your ramshackle house, etc, is a foreign one to those of us living in the west, but a common one in some of the poorer regions of Asia, regions which seem to be most prevalent. it is not surprising that a viral evolution of this nature is taking place, when one considers the living conditions of a very prevalent part of the population of Asia. And, having experienced the rapidity of the SARS infection first hand, I'm not pessimistic that we will have a new pandemic on our hands in the near future, but, frightful that one might erupt.

[Steve]

Bird Flu hits Disneyworld!

Oh No.... It got Donald!