An Example of Systems Analysis Done Well
Since the discovery Virus H5N1 colonizes humans and very often causes death Governments, media outlets, blogs, and just about everyone started panicking about a human pandemic. Now we can sit back a bit and better examine H5N1 with some objectivity. Panic is never the friend of Systems Analysis.
Forbes reports on Japanese-American research on where H5N1 likes to colonize. It appears that the virus prefers the lower lungs instead of upper respiratory system. This, at once, explains why the virus is almost always deadly and why it doesn't transmit easily from human to human. Being so low in the lungs means that it isn't going to get coughed up easily, and it means that treating it is very difficult. It causes viral pneumonia which frequently is the cause of death.
Why is this important? H5N1 could mutate to colonize the upper respiratory tract, but if it prefers and lower lungs for colonization it is possible that moving up the respiratory tract would weaken it by making it easier to treat as well as making its territory more dry and less protective in general. Imagine animals that are used to wet, lucious forest land having to more to open grassland and being showered by poison at the same time.
So what about the people who died from bird flu. News outlets like to stream headlines like 'death toll at 103'. Color me unimpressed. We have more people dying of plain old influenza per month than died of bird flu since we have kept track. More important is the reason why they died. It appears that their viral loads were very high and they were high because they were in close proximity to birds with H5N1. Aha! Now we have a better picture of the system.
Birds die from H5N1, humans can die from H5N1. So far so good. Virus jump species barriers. Also good. H5N1 has jumped species. Also good. This doesn't mean that we are all going to die from H5N1. Living organisms are lazy. It is a fundamental part of biology that you don't want to waste energy and you don't want to expend it unless you can be certain that the payoff will cover that debt. Otherwise it isn't worth it. Why would H5N1 make the jump to being able to colonize the upper respiratory tract? What evolutionary processes are pushing it towards that?
I am not a virologist or a biologist. So don't look for really awesome answers here. This is a thought excersize instead of a definitive answer. I'll make some guesses:
H5N1 is flaring up in birds and it'll do so for some while until it comes into better equilibrium. The weakest birds will die, stronger birds will breed resistance. H5N1 will adapt so that it doesn't kill 99% of its preffered hosts. After a while things will calm down again to occasional flares of bird influenza. As for humans, we are most likely not facing a pandemic, at least not from H5N1.
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