Thursday, July 30, 2009

Musings on the gradual development of a highly lelthal strain and simultaneous emergence in multiple locations.

This is related to my observations below about more countries seeming to be listing their first deaths. It is taken from a discussion on flutrackers.com in a member's area so I can't link into it. I'll edit it a little bit to remove references to the discussion it was part of.

One thing I am noticing, qualitatively, not quantitatively, is that deaths worldwide seem to be on the increase. Now there's certainly many reasons why this might be, and a large part of it could simply be due to an increase in the number cases, more cases will necessarily be more deaths. But is that all there is to it? Has much of the rest of the world reached whatever "critical point" in number of infections is necessary to start seeing an increase in the number of deaths? Or is there something else going on?

Apparently the CDC still thinks there is no change in the virus versus the vaccine consensus, but as we have now seen, as long ago as a month an apparently poorly understood but potentially very important change was discovered in Brazil. If this change was fit then we have no way of knowing how far it spread since then, and apparently we are not seeing sequences released in a timely manner anywhere, hence we really don't know what we are looking at now.

The lethal second wave struck three ports on the Atlantic Coast of three continents on or about August 22nd (Boston, MA, Brest, France, and Freetown, Sierra Leone). Shipping traffic can't have delivered the lethal strain to them all simultaneously, there is a fair chance that whatever ship(s) involved would have had a significant portion of their crew killed if they carried the lethal strain. But here is a different view.

Twentieth century pandemics (and possibly the Russian Flu of 1889) had a mild first wave that saw the virus get seeded around the world. In the case of 1918, the much more lethal second wave seems to have hit multiple places at roughly the same time. Perhaps this is what happened. As it spread around the world, the 1918 pandemic virus would have encountered other flu viruses and had chances to acquire various traits. As troops and war materiel moved around the world, these different strains would have spread back to other places, meeting up with different strains of the pandemic virus, or still other flu viruses, picking up additional traits. One of these, still not terribly lethal, but almost there, then got spread to these port cities. Three different ships from a single source could have done it, and perhaps it could have been South America, that being one location where the travel time would have been close to equal for all three destinations. With perhaps only one or two relatively small changes left, normal evolutionary pressures could have produced the more lethal strain simultaneously in different locations, and the new strain was much more fit, allowing it to spread.

So is Brazil pointing us that way? Perhaps they are the source of the new infections in Southern Mexico and Central America. Perhaps the "Sao Paulo strain" isn't the "final" more lethal version, but it could be one more step on the way thee. But with airline travel, the final version could easily crop up in multiple locations at the same time. We are looking for an immediate source, to areas where H5N1 is widespread, for instance. But whatever offspring H1N1 and H5N1 might produce will, perhaps, not be distinguishable from the current pandemic strain until a few more key changes crop up, and then it may already be worldwide.

The above was purely speculation, and I may be totally off-base.

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