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Wednesday, August 03, 2005

Penquinzee's Bird Flu Map

Go see the time sequence HPAI map from this thread on the Agonist's Disease outbreak board.

In the meantime, in case you don't see why what has happened in the last month is so ominous, this Recombinomics commentary should explain it:
The comments above are similar to an earlier report indicating 71% of ducks in the Mekong Delta were H5N1 positive. That earlier survey sampled all 11 provinces. This latest report indicates H5N1 is endemic to southern Vietnam. In the south, virtually all confirmed H5N1 confirmed human cases have been fatal, including the two last week. In contrast the fatality rate has fallen to less than 10% in the north, where another recovering patient was reported this week.

These rates could dramatically change, as birds begin to migrate back to Vietnam. The Qinghai lake outbreak involved a lethal H5N1 that was Amantadine sensitive, but had the PB2 E627K polymorphism, which had never been seen previously in avian H5N1. A related H5N1 is racing across southern Russia and about to spread through Europe.
A very virulent strain of H5N1 is the one that's now moving so rapidly out of China and into Europe.

So even a month ago it looked as if milder strains of bird flu were evolving in situ in Vietnam. Tests showed subclinical infections in humans. It also appeared very possible that these milder strains were the ones that would achieve efficient H2H human transmission and break out into the worldwide human population. This was a logical belief because acute human and bird cases were detected and isolated, so the chain of transmission was broken. Environmental factors were therefore favoring the evolution of H5N1 strains that were
  1. efficient at infecting humans and poultry, and
  2. not that lethal to humans to humans or poultry.
But now that hope is clearly gone. Even more disturbing is the suspicion that the Qinghai strain of H5N1 probably evolved in India as a result of their covert vaccination program for poultry. This could explain why such a virulent strain would have emerged. With poultry widely inoculated against H9 and/or H5 the environment now favored breakout of a strain that was extremely infectious and fast-replicating, and therefore able to overcome the partial immunity in the poultry stock. Such a strain may have emerged, jumped to wild geese, and arrived in China after the geese flew over the Andes in their annual migration. We now also know that China created an H5N1 vaccination for their poultry, which will favor further such mutations.

Natural selection doesn't really favor a rapid-killing strain such as this in wild birds. In general, the hosts get too sick too fast for it to transmit as efficiently as milder strains; a natural evolutionary sequence is for the milder strains to spread throughout the host populations. It's not that the more virulent strains won't randomly evolve, but sooner or later the milder strains work their way throughout the host population and, in effect, disadvantage the more virulent strains.

So this is why Dr. Niman of Recombinomics fears that bird flu vaccinations using a vaccine based on our current laboratory strains of H5N1 won't be a solution, and why he is agitating for international pressure on China to produce samples for the entire world to work with. We have to deal with the possibility that the strain that is now spreading through Siberia and toward Europe has been naturally selected to infect hosts that have already been vaccinated with something similar.

Forget the ticking clock. This is the clanging of the red alert klaxon. With widespread breakout into new wild and domestic bird populations the more virulently infectious strains will have the advantage on the leading edge of the spread of the disease. This is evolution in action, and it is not a pretty sight.

So much for the myth of a gentle Gaia. Mother Nature can be a raving murderous Medea and her true nature will become apparent very quickly.

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