The Black Death was one of the worst health pandemics to ever affect the world. It was at its peak in 1348-1350 and is estimated to have killed 30-60% of the population of Europe. The Black Death was characterised by large swollen lymph nodes or buboes in the groin, armpit and neck, which oozed pus and bled when opened. These symptoms where followed by acute fever and the vomiting of blood. During the later stages of the disease the skin of a person would turn black due to haemorrhaging and gangrene. Death usually followed two to seven days after initial infection. It is believed that the Black Death originated in China and spread to Europe via the Silk Road. The plague broke out a number of times from the 1300’s to the 1800’s.
What caused the Black Death?
During the time when the Black Death was causing such dramatic loss of life, little was known about bacteria, viruses and other substances that cause illness. It was widely believed that the Black Death was caused by bad air. This conclusion came from a medical facility in Paris which blamed the alignment of three planets causing this pestilence, as it was known, in the air.
Modern medical science has been able to extrapolate the cause of the Black Death. It is believed that the bacteria Yersinia pestis which causes the bubonic plague was responsible for the Black Death. This bacteria causes very similar symptoms to occur in infected hosts. DNA evidence from mass grave sites around Europe has shown that two distinct strains of the bacterium Yersinia pestis caused the Black Death. Both of these strains Y. p. orientalis and Y. p. Medievalis are now thought to be extinct.
There are a number of theories about how the Black Death spread so quickly across Europe. The predominate theory is that the fleas found on the black rat spread the bacterium when they bit people. The fleas affected with the Yersinia pestis would bite a host and then regurgitate numerous times causing a large number of bacteria to enter through the bite site infecting the host. Another theory suggested that the Black Death spread far too quickly for it to be attributed only to fleas and that it was actually passed from person to person. Other forms of bacteria and viruses have also been suggested, but all concede that it is difficult to know the exact cause because the pandemic took place so long ago.