Re: diseases and immunity
Mary Beth Williams (mbwillia@ix.netcom.com(Mary)
18 Jul 1996 12:44:34 GMT
In <4sjgiv$fgk@news.sdd.hp.com> geroldf@sdd.hp.com (Gerold Firl)
writes:
>
>In article <4sg1e7$8ki@sjx-ixn6.ix.netcom.com>,
mbwillia@ix.netcom.com(Mary Beth Williams) writes:
>
>|> In <4sebpn$edk@news.sdd.hp.com> geroldf@sdd.hp.com (Gerold Firl)
>|> writes:
>
>|> >Here's a simple model of the population dynamics of a pathogen
upon
>|> >reaching a virgin-soil host population: instead of taking several
>|> >years to die, these new hosts die in several days or weeks. They
are
>|> >also totally open to infection, with no appreciable immune
reaction.
>|> >This results in a new selection pressure on the pathogen: it needs
to
>|> >jump to a new host quickly, and it doesn't need to be very picky
about
>|> >what part of the body is colonized.
>|> >
>|> >The pathogen thus evolves to become highly contagious, which, in
>|> >practical terms, means being able to survive temperature
fluctuations
>|> >and dessication. Using TB as an example, it also will change so-as
to
>|> >no longer restrict itself to the lungs. (Bacteria have a varied
>|> >repertoir of cell-membrane proteins which attach to different host
>|> >tissues; lungs, intestines, blood cells, nerves, cartilage, etc)
In an
>|> >immunilogically experienced population, TB resides in the lungs;
in an
>|> >inexperienced host, that restriction is no longer necessary.
>
>|> Wrong, wrong, wrong... Haven't you read _anything_ I've posted? TB
>|> does _not_ reside only in the lungs in *immunilogically
experienced*
>|> populations!
>
>Thanks for clarifying that, MB. You're right. TB does not reside
>exclusively in the lungs among immunologically experienced
populations.
>TB is, however, primarily a pulmonary disorder - unless we're talking
>about virgin-soil epidemics.
So, what you're saying is that within these *virgin soil* TB epidemics,
people are dying of *skeletal TB* in a week or two????? Or are they
cannabilizing infected Europeans and thus developing the rare form of
intestinal and mesenteric lymphatic TB? Or do you have some *new and
previously unrecognised* form of the disease to which only you are
privy? Please, Gerold, at least _try_ and get familiar with how TB
manifests itself on the human body, both long term and short term.
>|> Skeletal TB effects 3-5% of ALL cases of TB, not only in *virgin
soil*
>|> populations.
>
>OK.
OK????? But you just said that in virgin-soil epidemics, pulmonary TB
was NOT the culprit... Thus, one would be left to believe that you were
hence describing skeletal TB as the perpetrator.
>|> >As soon as TB invaded amerindian populations, the new environment
led
>|> >to an evolutionary shift. Highly contagious strains were favored,
>|> >since the less-contagious ones died along with their hosts, while
more
>|> >transmittable strains had already infected a few other people
before
>|> >their host died.
>
>|> Geez, Gerold, where do you come up with this crap? TB remained
*highly
>|> contagious* in all densely congregated populations, Indian or
white,
>|> until the 20th century.
>
>Ya know, MB, it amazes me that someone who apparantly resides at the
>UMass anthropology department, and who has done actual physical anthro
>fieldwork, could have so little background in biology and evolution.
Believe me, Gerold, we could compare transcripts and vitas, and I'll
don't doubt for a second whose had the deeper immersion into biology
and evolution.
>Do you have any idea of the mean lifetime of an 18th or 19th century
>european who was infected with TB? One year? Two? Five? It's in that
>range.
Citation please. Actually, are you talking about the *mean lifetime*
of a person with *lung-fever* or *consumption*? With *lung fever*,
death usually came within days or weeks. According to Ornter and
Putschar, if one survived the former, then the disease could remain
dormant for many years before becoming active (usually due to some
stress, such as disease or malnutrition... Pregnancy was a major
trigger.)
>Whereas, in dubos and macneill are to be believed, TB in a
>virgin-soil epidemic killed much more quickly.
You've yet to give any supportive evidence to these citations (and its
not _my_ job to look this stuff up for you -- they're your citations,
you should know the primary research from which they derive.)
>What this means, in an
>evolutionary perspective from the PoV of the bacteria, is that it's
>absolutely necessary to jump to a new host as quickly as possible.
This is erroneous when it comes to TB, which is known to survive for
years, even decades, in non-living hosts (one of the reasons fizzies
working on TB cases have to take extra precautions -- I had to be
tested twice during one research project.)
>The lack of immunological defenses among indian populations results in
>an increased infection rate even without any changes to the bacteria.
>however, the bacteria will not remain passive in such a situation. It
>will evolve to maximize it's survival rate, just as the human
population
>does. That means an increased gene frequency for characteristics which
>aid infection, such as dessication-resistance.
See above... Between the existance of the original host (cattle) and
the longevity of the bacteria, TB doesn't need to *adapt* to human
hosts to survive.
>
>|> Go back and read some vital statistics records
>|> from New England in the 19th century, and you'll find that
>|> *consumption* accounted for nearly 50% of all *natural* deaths
between
>|> the ages of 18-50, and *lung fever* (rapid pulmonary TB) ranked up
with
>|> yellow fever, measles and smallpox.
>
>Makes sense to me.
Once again, your agreement with me contradicts your claims for
*epidemic TB*.
>
>|> >A big factor there is the way people will flee from an epidemic.
>|> >Crosby describes how refugees from disease spread it far and wide,
>|> >probably accounting for the devastation of the mound builders, far
>|> >ahead of any colonization.
>
>|> AH HA HA HA!!!!!! So Europeans were running around North America
in
>|> the 13th and 14th centuries???? The *moundbuilder* (early
>|> Mississipian) cultures, particularly those in the American Bottom
>|> region, e.g., Cahokia, dispersed prior to 1400.
>
>Sorry, I used the wrong term then. I was referring to indian
inhabitants
>of the mississippi/missouri/ohio river valleys in the early 16th
>century. I guess they were the successors to the mound builders.
But you said the *devastation* of these people ahead of any
colonization? The first incidence of massive epidemics we have in this
region (and only in the lower Mississippi) during the 15th century was
from DeSoto's *colonizing* efforts. I've always asserted that diseases
travelled ahead of their European hosts, but you're assumptions of
*flight* are premature... Late Mississippian cultures of the Southeast
US had highly developed trade and communication networks... It would be
more sensible to look at those as path of infection, rather than
Indians *fleeing* their homes, infecting everyone around them (do you
immediately run away from your house when your kids get chickenpox?)
>MB, it seems like you are very quick to jump on a minor point
>("moundbuilders" or "TB as pulmonary infection")
Gerold, its rather hilarious that you would consider the manifestations
of the disease in question as a *minor point*.
>but very unwilling to
>come to grips with the major issues. One problem I see with you is
>your
>extreme ethnocentric chauvinism (a characteristic you share with eric
>brunner); any fact which could in any way, no matter how remotely, be
>construed as indicating amerindian "inferiority" vis-a-vis europeans
>provokes an exagerated reaction: whether we're talking about
population
>density (you claim that the amerinds of the northeast had a population
>density equal to england at the time of contact), HLA-mediated immune
>response (you claim no genetic difference in disease resistance
between
>old world populations which had suffered from repeated epidemics and
>massive die-offs compared to amerinds who had never in their
>evolutionary past seen any exposure)
You've yet to post a shred of evidence to support your claims of
genetic differential in Old World versus New World immunity,
particularly in light of the negative evidence which has been provided.
European 5-year-olds and their Indian counterparts were equally
susceptible to smallpox, and their mortality rates the same.
and even our lamentable cannibalism
>thread from a few months ago, where you stubbornly denied, in the face
>of multifactorial evidence, that your beloved iroquois ate manflesh.
Gerold, you shoot yourself in the foot with this one... I guess you're
not at all familiar with the long-term animosity between the Abenakis
(Algonquins like me) and the Mohawks (the purported *cannibals* of
European ethnohistory.)
>How
>are you ever going to make it in acedemia with such a closed mind?
Don't waste your *heartfelt* concern on me, Gerold... As I said, lets
compare vitas... I'm doing just fine with my *closed mind*... Can you
say the same?
MB Williams
Dept. of Anthro., UMass-Amherst
|