- New Theory on 16th Century Mexican
Epidemics
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- David Stahle, a geologist at the University of Arkansas
in Fayetteville, has claimed that 2 of the most devastating epidemics to
hit the native population of colonial Mexico, contrary to the conventional
view, were not imported by Europeans. Rather they were caused by an
indigenous
virus and magnified by a mega-drought and the stress of
colonization.
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- Hantavirus-like hemorrhagic fever [epidemics] spread
across the Yucatan peninsula in 1545 and again in 1576, killing 17 million
people, including 80 percent of the native Indians, the same proportion
of the population that died in Europe during the Black Death. "It
shows that natural hazards like drought can interact with social conditions
to amplify an epidemic," said Stahle at a meeting of the American
Geophysical Union in San Francisco.
-
- The traditional view is that native peoples in the
Americas
succumbed to European diseases to which they had no natural resistance.
Although the 1520 epidemic that killed 8 million is still thought to have
been smallpox, a European disease, the [1545 and 1576 epidemics] now appear
to have been caused by a rat-borne hemorrhagic fever called Cocolitzli.
Medical journals have already published 2 articles this year arguing that
the symptoms recorded at the time most strongly resemble those of an
aggressive
hantavirus infection. They include blood gushing from every orifice, black
tongue and green urine.
-
- Hantaviruses can by carried by rats. Stahle noticed
that in both epidemics the disease was completely absent from the arid
coastal lowlands where rats do not live. He then plotted the amount of
precipitation in the epidemic regions based on a 2000-year tree ring
database
covering all of North and South America. He found both Cocolitzli
epidemics
occurred at the peak of a wet period preceded by severe droughts.
-
- During the drought, Stahle argues, rats would have stayed
near limited sources of water, thus forming a concentrated reservoir of
virus. When the rains returned, the rats spread around the countryside
to forage and took the virus with them. The population would certainly
have been more resistant if these droughts hadn't coincided with the period
of conquest and colonisation by the Spanish. This left the native people
hungry and poorly clothed. The Cocolitzli virus has never been found,
but Stahle says of virus hunters from the U.S. Centers for Disease Control
and Prevention in the field searching for a candidate virus in rats of
the region: "I would bet they find it in the next 5
years."
-
- [Filed by Jonathan Knight]
-
- -- Luiz Jacintho da Silva
<luiz_jacintho@uol.com.br
-
- [If the word "rats" is replaced by the word
"rodents" throughout the text, the hypothesis advanced by David
Stahle has some interest. Hantaviruses occur worldwide and hundreds of
thousands of cases of "Hemorrhagic fever with renal syndrome"
(HFRS) are recorded annually in China, Korea and Russia. Death rates range
from less than 0.1 percent for Puumala virus to up to 10 per cent for
Hantaan
virus. However, mortalities of greater than 40 percent are recorded in
the clinically distinct "Hantavirus pulmonary syndrome" (HPS)
recently recognized in North and South America. At least 174 of the
approximately
250 cases recorded in the USA and Canada have been associated with
infection
by a single virus, Sin Nombre virus. Consequently outbreaks of hantavirus
infection could have attained the fatality rates observed in 16th-Century
Mexico. A difficulty of the hypothesis is that it draws inferences from
the potential population dynamics of a presumed vector. Rodents can be
vectors of many pathogenic agents; it was the bacillus _Pasteurella pestis_
in the case of the Black Death of medieval Europe. Isolation of novel
hantaviruses
in Mexico will not support the hypothesis; nothing short of a catastrophic
hantavirus-associated outbreak would be sufficient. - Mod.CP]
....................cp/pg/es
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