Controversies
and Reexamination of the Black Death
Magnification of Yersinia pestis
bacterium.
http://www.bibliopolis.org/graficos/cromo/crom0011_3.jpg
Since the
acceptance of the germ theory and the identification of Y. pestis in
1894, it has been accepted that the Black Death was a pandemic caused by this
organism. Now with greater knowledge of
the transmission of disease and the characteristics of each organism, as well
as the development of technologies that are allowing us to examine “plague
pits”, scientists are calling this basic assumption into question. Currently there are investigations into
whether the etiologic agent was in fact Yersinia pestis or whether it
could have been a filovirus causing a viral hemorrhagic fever (Duncan and Scott
315). Some of the evidence presented
against Y. pestis being the responsible agent includes the fact that
black rats were not found in the countryside, Norwegian rats did not appear in
England until 60 years after the Black Death, quarantines were somewhat
successful and others (Duncan and Scott 321).
Study of the
archeological records is limited since Y. pestis does not affect the bones
of the skeleton (Roberts and Grauer 109).
Thus, information must be collected using records, which were poorly
kept at that time, circumstantial archeological evidence such as rat bones and
study of plague cemeteries, and by drawing assumptions based on our current
knowledge of disease. Research into this
question has been aided by the use of DNA recovery in dental pulp of presumed
plague victims but the results are contradictory. Some labs are finding the presence of a Y.
pestis-specific DNA polymer in these
remains (Drancourt et al. 12637) while others are not (Gilbert et al. 341).
Another area of
current study is the finding in direct descendents of English plague victims of
the presence of an allele that appears to provide protection against Yersinia,
smallpox and HIV. This allele, known as
the CCR5 {delta 32} deletion allele is found at a much higher rate in Caucasian
north Europeans than would be expected by the limited time frame for selection
pressure. It is interesting to note
however that this allele is absent in African, Asian, Middle Eastern and
American Indian populations (Galvani and Slatkin 15276).
The
Plague Yersinia
pestis The Spread Cultural Effects Controversies Modern
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