In the last 200 years or so, humanity has made great strides in the development of medicine and medical technology. Despite this, there are still many plagues and pandemics, both from centuries ago and from the modern era, that confuse or frustrate our understanding of medicine.
Some can only be explained as outbreaks of hysteria or mass hallucinations brought on by intense social pressures. Others are even more mysterious, lacking any sort of logic or reason. Here is a list of 10 plagues, which have baffled and bewildered the doctors of the past and present alike.