Controversies and Reexamination of the Black Death


Magnification of Yersinia pestis bacterium.



          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 Plague     References