fleas were the vector of the bubonic plague.
what was the vector of the bubonic plague?
fleas
in addition to arguing that the rat population was insufficient to account for a bubonic plague pandemic, sceptics of the bubonic plague theory point out that the symptoms of the black death are not unique (and arguably in some accounts may differ from bubonic plague); that transference via fleas in goods was likely to be of marginal significance; and that the dna results may be flawed and might not have been repeated elsewhere or were not replicable at all, despite extensive samples from other mass graves. other arguments include the lack of accounts of the death of rats before outbreaks of plague between the 14th and 17th centuries; temperatures that are too cold in northern europe for the survival of fleas; that, despite primitive transport systems, the spread of the black death was much faster than that of modern bubonic plague; that mortality rates of the black death appear to be very high; that, while modern bubonic plague is largely endemic as a rural disease, the black death indiscriminately struck urban and rural areas; and that the pattern of the black death, with major outbreaks in the same areas separated by 5 to 15 years, differs from modern bubonic plague—which often becomes endemic for decades with annual flare-ups.
black death
while "y. pestis" was in some samples collected from grave sites in various burial sites across europe, many skeletons did not yield the dna. the fact that bubonic plague dna was present does not necessarily mean that bubonic plague was the cause of death; the individual could possibly have survived a bout of bubonic plague and died of another disease agent. "y. pestis" might well have been the cause of death, but since archaeologists have often specifically sought evidence of "y. pestis", other important information is potentially neglected. while rats were present in major sea ports across europe, the evidence for rats in rural communities in northern europe is scanty. the fact that the epidemiology of the black death and its rapid spread does not match modern bubonic plague is an indication that all possibilities should be considered, even in the case that the epidemic was caused by bubonic plague
theories of the black death