It’s a proven fact that nothing has killed humans more than the infectious diseases. The shift from hunters and gatherers to the sedentary life or agrarian life, might have led to the spread of these infectious diseases in human beings. With the passage of time, human evolved, human interactions increased between the communities through the passage of trade; the scope has increased.
Contact between humans and animals probably, has facilitated the transmission of zoonotic pathogens. Climatic changes have fueled the transmission of pathogens, for example, zika or dengue. The increased use of land due to rising population also affects the distribution of disease-carrying vectors.
Furthermore, the graph of infectious diseases rises as a result of poor sanitation, land exploitation, climatic changes, and increased human mobility.
Finally, infectious agents that could be used as bioweapons; thus, it’s a matter of concern for humanity as well as international security.
Ancient perception of the plagues and pandemics:
Many ancient texts have suggested that many ancient societies believed in the spirit and the God.
But what is interesting is their faith in the holy spirits and Gods to have inflicted diseases and destruction on those who have committed a sin and they deserve a wrath. These unscientific perceptions were quite prevalent in nature during the Dark Ages.
There aren’t enough historical documents to trace the exact timeline of the pandemics, as a few historians have highlighted that the first epidemics having ravaging effects on humanity might have taken place post 420BC.
Plague of Athens: a disease which remained unidentified in those days. The Greek perspectives suggest that it had emerged from Ethiopia and later spread throughout the different regions including the Mediterranean basin. The plague of Athens has proven deadly for humanity as it has killed 20-30% of the population of the region.
Plague of Justinian: the outbreaks of the plague took place 542CE, claiming the lives of thousands of people. The first known pandemic of bubonic plague, as mentioned in some of the recent studies, it has emerged from central Asia and later spread to Byzantine empire and Mediterranean basin.
As a generic cause of the spread of any infectious disease, this time too, trade and war facilitated the spread of the plague. The rise in the number of cases was so rapid that no one was safe, corpses littered on the streets of the empire. There was evidence of burial pits which signifies the alarming rate of deaths.
Black Death: the second pandemic of bubonic plague, a disease caused by the bacterium Yersinia Pestis, has its origin in the steppes of central Asia and was later spread across Europe in 1346-53. Same as usual; trade remains one of the constant causes of spread.
Furthermore, it manifested strongly in densely populated areas, which lack proper sanitation. In a couple of years, the disease has killed 200 million humans globally. This disease had catastrophic effects on Europe; there was a series of wars and a slump in trade.
Despite the advances made in the realm of medicine, such deadly diseases still claim plenty of victims. Plague still reappears regularly; poverty-stricken and malnutrition individuals continue to face the disproportionate horrors of such disease.