A pandemic (from the ancient Greek pándēmos, "what affects all people", "public", "general") is the rapid spread of a disease on a global scale, and consequently involves a large part of the world's population. Such a situation presupposes the lack of immunization of man towards a highly dangerous pathogen. In human history, there have been numerous pandemics.
According to the World Health Organization,
the conditions for a real pandemic to occur are three:
- the appearance of a new pathogen, for which no effective cures are known;
- the ability of such an agent to affect humans;
- the ability of this agent to spread rapidly by contagion;
Throughout history, pandemics have occurred since ancient times, often involving the whole world known at the time. Therefore, the Covid19 pandemic that afflicts us today is just one of the countless pandemics that have hit our planet. Most of the viruses that have caused pandemics are zoonotic, that is, originated from an interspecies contagion; some typical examples are influenza, tuberculosis and Covid19.
The encounter between European explorers and indigenous peoples from other parts of the world was often the cause of epidemics and very violent pandemics. Smallpox killed half the population of Hispaniola in 1518, and sowed terror in Mexico around 1520, killing 150,000 people (including the emperor) in Tenochtitán alone; the same disease struck Peru violently in the following decade. Measles claimed another two million victims among native Mexicans in the seventeenth century. Still between 1848 and 1849, about a third of the native population of the Hawaiian Islands died of measles, whooped cough and flu.
There are also many epidemics of which historical evidence remains but of which it is impossible to identify the etiology, as they were generically called pestilences, due to limited scientific knowledge. A particularly striking example is that of the so-called sweat disease that struck England in the sixteenth century; more fearsome than the bubonic plague itself, this disease had a very rapid exigent course.
Among the most catastrophic pandemics are:
- A typhoid fever during the Peloponnesian War, 430 a.C. Typhoid fever killed a quarter of Athens' troops and a quarter of the population within four years. This disease weakened the resistance of Athens, but the great virulence of the disease prevented further expansion, as it killed its hosts so quickly that it prevented the dispersion of the bacillus. The exact cause of this epidemic was never known. In January 2006, researchers from the University of Athens found traces of a bacterium now extinct, very similar to that of typhoid fever, in the teeth coming from a mass grave under the city.
- A pandemic allegedly of smallpox, carried by troops returning from the war against the Parthians in the provinces of the Near East, killed at least five million people. Between 251 and 266 there was the peak of a second pandemic of the same virus, the so-called "Cyprian's disease", named after the bishop of Carthage who wrote about it; it seems that in Rome and in the Greek cities at that time 5000 people died a day. It is estimated that between 5 and 30 million people have died.
- From 541; it was the first known pandemic of bubonic plague. Starting from Egypt he reached Constantinople; according to the Byzantine historian Procopius, almost half of the inhabitants of the city died, at a rate of 10. 000 victims per day. The pandemic spread to the surrounding territories, killing a quarter of the inhabitants of the western Mediterranean Sea regions. The dead are estimated at between 50 and 100 million.
- Starting in the 1300s. Eight hundred years after the massacre of Constantinople, the bubonic plague made its return from Asia to Europe. In 1346 it was brought to Eastern Europe by the Tatars who besieged the Genoese colony of Caffa (today's Feodosia), and later to Sicily by Italian merchants from the Crimea, spreading throughout Europe and killing twenty million people in six years (a third of the total population of the continent). The Italian-American researcher Alexander F. More has shown with epidemiological and historical data that the five years of the Black Plague, with mortality from 40 to 60%, caused such an economic crisis that air pollution caused by lead reached the lowest of the last two thousand years. Thisphenomenon has been partially repeated during the COVID-19 outbreak. It took two centuries for europe's population to reach the number before the pandemic again.
- Also called "camp fever" or "naval fever" because it tended to spread more quickly in war situations or in environments such as ships and prisons. Already emerged at the time of the Crusades, it struck Europe for the first time in 1489, in Spain. During the fighting in Granada, the Christian armies lost 3000 men in battle and 20.000 for the epidemic. Also because of the typhus, in 1528 the French lost 18. 000 men in Italy; another 30.000 people fell in 1542 during fighting in the Balkans. Napoleon's great army was decimated by typhus in Russia in 1811. Typhus was also the cause of death for many inmates of Nazi concentration camps during World War II.
The Spanish Flu
- 1918-1920. It began in August 1918 in three different places: Brest, France; Boston, nel Massachusetts; Freetown, in Sierra Leone. It was called "Spanish" although it did not originate in Spain as the Spanish media were initially the only ones to talk about it, not being subjected to the censorship caused by the First World War, ongoing in the same years, in which Spain had not taken part. It was a particularly violent and lethal strain of influence. The disease spread throughout the world, killing 50 million people. It ended after 18 months and 3 waves.
The Asian Flu
1957-1960. First detected in China in February 1957, it later reached Europe and the United States. It caused about 2 million deaths worldwide. The virus that caused it was H2N2.
The Russian Flu of 1977
It began in the north of China and the Soviet Union. About 700. 000 people have died worldwide, it is caused by a strain of the H1N1 virus that looked very much like a strain circulating around the world in the 50s and many researchers believe that the virus was released to the general public in a Soviet laboratory accident.
The Hong Kong Flu, 1968-1969
The H3N2 virus strain, which emerged in Hong Kong in 1968, reached the United States in the same year where it made 34.000 victims. It caused about 2 million deaths worldwide. A virus belonging to H3N2 is still in circulation today.
Flu A-H1N1, 2009-2010.
Also called "swine flu" because it is transmitted from this animal to humans. Its initial outbreak took place in Mexico, then extended in just 2 months to almost 80 countries. In Europe and neighboring countries, as of August 31, 2009, there were 46.016 confirmed cases and the confirmed deaths 104, while inthe rest of the world the cases of death ascertained were 2.910. As of August 6, 2010, when the WHO officially declared the end of the pandemic, the confirmed cases worldwide were 1.632.710 and deaths 18.449.
The AIDS pandemic
Since 1981, caused by the HIV virus. It spread exponentially in all the countries of the world. In 1996, drug therapy was developed that blocks its course, but does not eliminate the virus from the bodies of individuals; thanks to this treatment the disease can be made chronic and rarely becomes lethal (in the developed world), but its contagion continues, linked to behavioral factors. As of 2020, about 75 million cases and about 35 million deaths are recorded.