THE BIGGEST EPIDEMICS IN HISTORY

Given this time when there is a lot of talk about coronavirus, this month I would like to talk about the biggest epidemics in history.

Epidemics have always accompanied Man's history. Some of these such as plague, smallpox or Spanish flu have changed the history of humanity for their demographic, social and economic effects.

Before I start talking about epidemics, I have to say that epidemic deseases can be divided into four families:

     1)    The diseases affecting the digestive system: diarrhea, cholera, salmonella etc. They are mainly  transmitted through water contaminated by faecal germs.

    2)    The diseases whose microbes are transmitted from person to person through water droplets emitted with coughing and sneezing: flu, measles, tuberculosis etc. Contagion occurs by breathing these infected droplets suspended in the air or falling on food or objects. 

      3)    Sexually transmitted diseases: AIDS, hepatitis B, syphilis etc.

      4)    The diseases spread through insect bites and bites (fleas, lice, ticks, mosquitoes): malaria, yellow fever, tropical fever, zika etc.

THE JUSTINIAN PLAGUE

The Byzantine Empire was in one of its heyday when a plague epidemic overshadowed the power of Emperor Justinian. It was the first known plague epidemic. The disease, and with it fear and hysteria, spread at a dizzying rate in Constantinople, a city of almost 800,000 inhabitants. And from there to the whole Empire. Justinian himself was also a victim of the plague, but managed to heal. By the end of the epidemic, the imperial capital had lost nearly 40% of its population, and 4 million people had died throughout the empire. The economic consequences were catastrophic, because there were times when the death toll exceeded that of the living. Many historians see in this phase of weakening the Byzantine Empire a dividing line between the decline of Antiquity and the birth of the Middle Ages.

THE BLACK PLAGUE

The black plague was already known when humanity experienced the worst epidemic in the mid-fourteenth century (between 1346 and 1353). She was known for her history, but her causes and treatment were completely ignored. This, together with the speed of spread, have made it one of the largest pandemics in history. Only five centuries later was discovered its animal origin, and its connection with rats, which during the Middle Ages lived in large cities with people and even moved with the same means of transport, such as ships, for example, towards distant cities, bringing the virus with it. The numbers that left this epidemic behind are shocking. According to the data held by historians, the Iberian peninsula is estimated to have lost around 60-65% of the population and Tuscany between 50 and 60%. The European population went from 80 to 30 million people.

THE SMALLPOX

The so-called smallpox virus, the spread of which in humans has been known for at least 10,000 years, is the cause of the disease known as smallpox. Its name refers to the pustules that appeared on the skin of those who suffered from it. It was a serious and extremely contagious disease that decimated the world population since its appearance, reaching mortality rates of up to 30%. It expanded massively in the New World when the conquerors began to cross the ocean, hitting a population with very low defenses against new diseases terribly, and in Europe it had a period of dramatic expansion during the eighteenth century, infecting and disfiguring millions of people. Fortunately, it is one of the only two diseases that man has managed to eradicate through vaccination. It was precisely against this disease that the first vaccine was discovered. It was Lady Mari Montagu who initially developed some key observations in Turkey and, almost 100 years later, Edward Jenner scientifically demonstrated their effectiveness. In 1977 the last case of infection of the virus was recorded, which has since been considered extinct.

SPANISH FLU

In March 1918, during the last months of the First World War, the first case of Spanish flu was registered, paradoxically, in a hospital in the United States. It was named after Spain because it remained neutral in the Great War and information about the pandemic was circulating freely, unlike the other countries involved in the struggle who tried to hide the data. This virulent strain of the influenza virus spread all over the world at the same time as troops moved on European fronts. Health systems risked collapse and funeral homes were unable to keep up with the victims. Recent studies have revealed more precise data. The global mortality rate was estimated to be between 10 and 20% of the infected, and between 20 and 50 million people died worldwide. There are those who even speculate that the 100 million victims were reached.

ASIAN FLU

First recorded in the Yunan Peninsula, China, the avian influenza A (H2N2) virus appeared in 1957 and spread worldwide in less than a year. At that point, the role of the World Health Organization (WHO), the UN medical arm created in 1948, each year designed a vaccine intended to mitigate the effects of flu mutations. Although medical advances in relation to the Spanish flu pandemic have helped to contain the advance of the virus much better, this pandemic has experienced one million deaths worldwide.

HUMAN IMMUNODEFICIENCY VIRUS (HIV)

One of the most serious and most recent pandemics known by today's society is that of the human immunodeficiency virus, HIV, better known as AIDS. The first documented cases appeared in 1981, and since then the virus has spread all over the world, concentrating much of the efforts of world health organizations. Its origin was thought to have been animal, and its effects include weakening the immune system. In itself, therefore, the virus is not lethal, but its consequences are, because they leave the organism defenseless in the face of other diseases. Its contagion occurs by contact with body fluids. Although these transmission routes make it less contagious, a priori, than other viruses such as influenza, initial ignorance has allowed it to spread very quickly. HIV is estimated to have caused around 25 million deaths worldwide.

COVID-19

Already in November 2019 in the Chinese city of Wuhan, the most populated city in the eastern part, a pivot for trade and exchanges, a number of anomalous pneumonia were registered. In the following January, the Chinese authorities told the local media that the pathogen responsible for those pneumonia was a new strain of the same family of coronaviruses responsible for Sars and Mers. At the end of January the risk of the epidemic spreading went from moderate to high, so much so that the OMS declared the public health emergency of international interest. The name of the new disease caused by the coronavirus arrived on 11 February. The name chosen by the OMS is Covid-19, co and vi to indicate the coronavirus family, "d" to indicate "disease" and finally 19 to emphasize that it was discovered in 2019. Since that time, the virus has spread from China all over the world, the rest is history of these days.

The current epidemic does not find comparisons for impact on public health measures in the recent past, both for the number of cases diagnosed and for the number of countries involved on all continents. An epidemiological event of this magnitude has blocked the economies and displacements of over half of the world's population. The pandemic closest in time to entity to the current one is certainly the so-called "Spanish flu" but the connections and economies involved are not comparable.

An event like this happens every hundred years.

EDOARDO