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Re: diseases and immunity
Mary Beth Williams (mbwillia@ix.netcom.com(Mary)
9 Jul 1996 20:36:01 GMT
In <4ru3hs$bdj@news.sdd.hp.com> geroldf@sdd.hp.com (Gerold Firl)
writes:
>
>In article <4rom4t$fso@sjx-ixn4.ix.netcom.com>,
mbwillia@ix.netcom.com(Mary Beth Williams) writes:
>
>|> The reason that measles, and many other highly communicable
*childhood*
>|> diseases are so devastating in *virgin* populations is related to
the
>|> effects of those diseases on particular age groups, e.g., adults
and
>|> very young children experience, for reasons not completely
understood
>|> even by the medical field, higher mortality rates than do older
>|> children and pre-teens.
>
>There's more to it than that, MB. As gazis-sax wrote:
>
>|> >Another example is the Ojibway (?) Indians who were first exposed
to
>|> >tuberculosis in the early twentieth century. At first, when the
>|> >disease hit, *nobody knew what it was*. It did not act like
normal
>|> >tuberculosis which forms tumors in the lungs. In the first
generation
>|> >of Ojibway TB victims, tumors formed in the brain, liver, and all
over
>|> >the body! It was only by examining the tumors under a microscope
that
>|> >the cause was recognized as TB. Again, in subsequent generations
it
>|> >resembled the TB we all know and love.
>
>|> Is the case of the Ojibway you reference cited in MacNeil or
another
>|> source? (I'd like to look at it first hand, as the groups from the
>|> Upper Midwest have shown indications of TB for centuries, due to
their
>|> almost constant contact with Euros from the 16th century, and in
fact,
>|> fizzy work done on purported *pre-Contact* TB cases come from that
>|> area, thus I have a difficult time accepting that any group in the
>|> region was first *exposed* to TB within the last century.)
>
>Mcneill does mention something like this, discussing a group of
>"canadian indians" on their first exposure to TB. He doesn't say when
>it happened; I assumed 19th century. He does say that at first
>exposure, the infection looked totally unlike TB; not only were the
>internal organs attacked, but also the spinal meninges. By the third
>generation, the infection settled down into the familiar pulmonary
>pattern.
Joel's example was 20th-century Upper-Midwest, not 19th-Century Canada,
possibly two very different situations, as it is nearly impossible for
20th-century Indians in the Midwest _not_ to have been in contact with
Europeans, or other Indians who had been in contact with Europeans, and
hence, not to have been exposed to TB. Canada, on the other hand, is a
very large place, and, although unlikely, it is possible for a few
groups in remote extreme Northern or West-Central areas to have not
been exposed to TB in the 19th century.
HOWEVER, you're going to have to give a better citation than a generic
*MacNeil*, particularly when giving the level of detail regarding the
symptoms of the infection. What were the bases for MacNeil's purported
assertions that this in fact was TB? Ethnohistoric accounts from the
19th century, or skeletal analysis by fizzies from the late 20th? As
I've worked on cases where skeletal TB is hypothesised to have been
present, I'm _very_ familiar with the fizzy literature, and only know
of a few research projects performed on 19th-century Canadian Indians
where skeletal TB was hypothesised to have _perhaps_ existed (over 13
other diseases also leave skeletal lesions similar to TB), and these
are all in populations who had been in contact with Europeans for
centuries (remember, the French were active in Canada for nearly a
century before the British were in the present-day US.)
And if this was in fact a 19th-century population, HOW do we know that
the internal organs were affected???? Autopsies (on Indians in remote
areas of Canada???) Physical anthropologists, unless presented with
*wet* material, have nothing to determine the past pathologies of their
subjects other than the bone, and the diagnosis of skeletal TB is based
in part on the presence of *destructive lesions extending to more than
four vertebrae and significant amounts of bone regeneration* (Ortner
and Putschar, pg. 167)
>I have tried to explain this to you before; it's probably useless, but
>I'll have another go: the human immune system has enormous
>*variability* - that's how it manages to keep ahead of rapidly
>mutating pathogens. The immune system must be able to deal with a
>large variety of infectious agents, which are constantly changing;
>that's why humans are sexually attracted to those with different
>immune factors. When TB first appeared as a virgin-soil infection in
>the tribe cited above, many of the individuals were carrying an immune
>system which had no resistance to TB, so the TB bacilli rapidly spread
>throughout their entire body and killed them. Those individuals who
>happened to have an immune response which recognized and destroyed the
>TB survived, and by the third generation all the children of that
>tribe had those immune factors. This is evolution in action.
*Rapidly spread throught their entire body and killed them*???? Then
_how_ do you know that they were victims of TB???? People whose bodies
show evidence of TB don't die of it rapidly -- it takes time for the
disease to wreak havoc on the skeleton, whether it be the skull,
vertebrae or long bones (all of which may show evidence of TB.) And
since it is asserted by the ethnohistoric record that this didn't even
*look* like TB, how do you know that it was in fact TB?
As an aside, TB mortality rates among whites in the New World were
exceedingly high (I personally did a study of a nineteenth-century
white community in Connecticut where 15-20% of natural deaths were
attributed to *consumption*, i.e., TB), and thus Europeans never did
appear to develop an immunity to the disease. How does that effect
your your *sexual attraction* hypothesis?
It's very
>similar to what happened in europe when syphilis first appeared: the
>individuals who were unfortunate enough to have no immunological
>response to the syphilis spirochete would die a few days after being
>infected. They were eaten alive by the spirochete. Nasty, but that's
>the way it works.]
Do you have a citation for this? As syphilis would have first appeared
in 15th-century Europe, I'm not sure I trust post-Medieval Europe's
understanding of pathologies the way you do. And, once again, if they
died off right away, there would be nothing on the skeletal *record* to
show evidence of such a demise.
>
>|> The problem with using TB as an example in explaining the *massive
>|> depopulation* of the Americas is that it really was very
>|> insignificant... TB shows up _after_ the large die-offs, and in
fact
>|> may have been only a *secondary* infection, that is, attacking
those
>|> individuals whose immunities were weakened by smallpox, measles,
etc.
>
>You can't see the trees for the forest, mb. Smallpox was the mosd
>important killer, but if smallpox hadn't existed, then another disease
>would have taken its place. If TB got to an isolated population before
>smallpox did, then TB would would kill them off. No one is using TB to
>explain the american die-off; the example was cited to illustrate the
>vulnurability of previously-unexposed populations to new pathogens.
TB never would have taken the place of small-pox or any other childhood
infection, as infection rates have never reached those of these other
diseases, in Indian or European populations. (In fact, it has been
strongly hypothesised that TB was present in pre-Columbian populations
in the Upper Midwest.) You example is an extremely poor one, Gerold,
as there appears to be some parity between Indians and non-Indians when
it comes to mortality rates from TB.
MB Williams
Dept. of Anthro., UMass-Amherst
Source:
Ortner, D.J. and W.G.J. Putschar (1985) Identification of Pathological
Conditions in Human Skeletal Remains. Smithsonian Institution Press,
Washington.
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