One of the consequences of humans living closely together in cities was the way infections found it easier to take a hold on a population, passing rapidly from person to person. And the expansion of long-distance trade meant that disease could travel from one corner of the world to the other, a trend that has speeded up over time, especially since the spread of passenger aviation.
In some populations, certain diseases are endemic. Societies tend to adapt to them – they become part of everyday life and death. But sometimes a given disease will explode into an epidemic, and if it then spreads more widely, across frontiers and continents, it may turn into a pandemic. Such events can have dramatic impacts on the course of human history.Medical historians do not like to make broad retrospective diagnoses of diseases described in ancient, medieval or early modern sources. The word ‘plague’ has been a blanket term for various different lethal epidemics, such as the plagues mentioned in the Old Testament, and the Plague of Athens of 430–427 BCE.
The first case that may have been bubonic plague (caused by the bacterium Yersinia pestis, spread by rats and fleas, and characterized by buboes, black swellings in armpit and groin) was the Plague of Justinian in 541–4 CE. This epidemic spread all around the Mediterranean, killing perhaps one-quarter of the region’s population. It hit at a time when it looked possible that the strength of the old Roman empire might be restored. Although the western Roman empire had been overrun by Germanic tribes in the previous century, the eastern emperor, Justinian, had embarked on an ambitious campaign of reconquest. But the chaos and devastation inflicted by the plague shattered all dreams of reunification.
The Black Death that spread from Asia in the 14th century, killing perhaps one-third of the population of Europe, was probably a mix of bubonic, pneumonic and septicaemic plague. The Black Death was a turning point in European social, economic and intellectual history. With so much of the agricultural workforce dead, those who survived could demand higher wages. The landowners put up resistance, and this provoked peasant revolts.
Many took the Black Death as a sign of God’s displeasure, both with his people and his Church. Various groups consequently questioned papal authority, anticipating the Protestant Reformation of the 16th century.‘Where are our dear friends now? Where are the beloved faces? … What tempest drowned them? What abyss swallowed them? There was a crowd of us, now we are almost alone.’Petrarch, Italian poet of the 14th century, expresses the loneliness of the survivors of the Black Death.
The Black Death spread to Europe from the Black Sea via ships of Genoese traders. In the 16th century the European ‘voyages of discovery’ to the New World caused similar devastation (see here).
By the early 20th century there had been a revolution in our understanding of the causes of disease, but this could not prevent the emergence of new pandemics. Although outbreaks of influenza had occurred for centuries, the strain that swept the world in 1918–19, known as ‘Spanish flu’, caused unprecedented devastation. Estimates of mortality range from 50 million to 100 million, many more than the death toll of the entire First World War. Unlike other flu outbreaks, most of the victims were aged between twenty and forty, which maximized the demographic impact.
Also, in 2020 outbreak of influenza COVID19 started from Chine very impactful to workd economic activities, sweep giant retails Nd cause high unemployment rate all over wolrd.
Some scientists believe it is only a matter of time before humanity experiences another such pandemic.
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