jreelawg said:
Second, we seem to have been anticipating or at least concerned about a possible devastating avian flu outbreak. What is the basis for this concern? What in recent times happened to make the risk of mutated flu greater?
Humans are just one part of our general ecology in which we live, and in fact, we are food to literally billions of microbes. The basis for our concern about global pandemics is that viruses mutates continuously and has the ability given the right mutations to spread between species. This is not something extraordinary, but is a constant factor in the history of life and humanity. We have influenza viruses who spread between humans and humans and between other species. Genetic changes can occur that makes the virus able to spread between other animals and humans. Further changes can allow it to spread between humans and other humans. At this moment, we are between these two situations: non-human animal to human transmission has been confirmed, but no substantial human-to-human transmissions has been found. The thing to understand is that global pandemics are not rare occurrences -- they happen about once ever thirty years on average, but it is hard to impossible to predict when the next pandemic will happen. As always the question is not if a pandemic will occur, but when.
Third, does anyone know why common forms of the flu happen every year, but deadly forms like the 1918 form die out? Is this new virus going to come and go quickly, or will it be something new that people get every year?
There are a few important differences between seasonal influenza and pandemic influenza. There is a constant evolutionary arms race between influenza viruses and their hosts. Both "come up with" new exploitations and defenses against each other and because the mutations of the viruses are so rapid they can exploit individuals who had developed immunity to earlier strains. At best, the immunity to earlier strains can only provide a partial protection, if that, against newer strains. This is why seasonal influenza does not "go away".
Now why does dangerous pandemics like the 1918 influenza pandemic "die out"? It is a very good question. During an epidemic or pandemic of any form of pathogen, the virulence of the of the pathogen will decline over time as a general rule (provided there is no increased spread trade-off to high virulence). This is because pathogens who kill their hosts rapidly will have less opportunity to spread than others and this is of course the key factor in the evolution of pathogens. This means that after a few waves of the pathogen, you are either dead, not infected or you have survived because you had before or have gained some immunological defenses. There are simply very few avenues left for the pathogen other than to fade in the microbial background noise or run out of viable carriers. Naturally, you can "exterminate" the pathogen as well by issuing world-wide vaccinations and so on. The black death and small pox are two examples of this, respectively.
Fourth, why is this virus rampant when it isn't flu season? If this were to happen in the winter would it be much worse? And are we now going to have to worry about the flu year round?
Pandemic influenza and seasonal influenza are not the same thing. As the name suggests, seasonal influenza is seasonal, whereas pandemic influenza is not.