Re: avian flu spreading fast, was changes in food

Per Janet Baraclough:
> My understanding is that within each affected
>population as a virus-strain rolls across it, that particular flu virus
>strain loses effect within months. The weaker victims die, the
>stronger develop antibodies, that virus-strain has no suceptible hosts
>left to replicate in, in that location.

That would be my image of the process too - qualified by the historical
observation that there are often two waves of the disease that have varying
degrees of lethality to different portions of the population. (i.e. sometimes a
wave decimates the young and other times it hits the older people the hardest)

The zinger is how many die. In the case of H5N1, it might not be a matter of
being "weaker".

One of the biggies with H5N1 is the total lack of residual immunity among the
human population. In that sense, everybody is "weak" - as were the American and
South American Indians when Westerners arrived; and whose populations were
virtually wiped out in a very short period of time, regardless of military
predations by smallpox, measles, and whatever other viral diseases the European
population had developed various degrees of tolerance for.

Most people have some immunity to most versions of the flu because they have
been exposed to other strains that have some traits in common that are
recognizable to the immune system.

OTOH, my understanding is that there's nothing like H5H1 antigens in our blood
streams. I'm no expert, but that would seem to me to explain the very high
death rate among people who have contracted it from birds so far. The question
is whether or not that lethality will carry over when it mutates or rearranges
to human-contagious form. As I understand it, in the 1918 form, it was a
newfound ability to lodge deep in the lungs that made the second wave of it so
deadly.


> The previous pandemics were all before the days of frequent mass air
>travel, so probably their distribution won't be applicable today
>anyway.

Bingo! Add to that the fact that a doctor cannot tell whether someone has
ordinary flu or bird flu by examining the person and I think there's a
possibility of it spreading worldwide before the various disease tracking
organizations realize what is happening.
--
PeteCresswell
.

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