“The great epidemics have upset the history of humanity. There has been practically one per century”, informs Dr. Jean-Piere Dedet, doctor and microbiologist, professor emeritus of the Faculty of Medicine of Montpellier and full member of the Academy of Sciences overseas*. Let us cite the plague in the 14th century which halved the population of Western Europe in 5 years, syphilis during the Renaissance, cholera in the 19th century with 7 pandemics from 1817, and, in the 20th century, influenza (Spanish flu which killed between 20 and 50 million people, the Asian flu, the Hong Kong flu)… “From the moment when we learned about microbiology at the end of the 19th century, the arrival of antibiotics and vaccines, there were fewer epidemics and Man felt he was in control of infectious diseases. In 1980 , the AIDS epidemic, the first modern epidemic, reminded us that there will always be epidemics and that we have to live with them”, teaches Dr. Dedet.
Why epidemics?
This specialist explains that “In all epidemics there is what Max Sorre called the pathogenic complex: an interaction between the microbe, the hosts (human or animal) and the external environment“.
A telling example: the cholera epidemic in the 19th century. “Cholera was just rampant in India. The cataclysmic eruption of an Indonesian volcano in 1815 followed by a year of heavy rains changed the ecology of great rivers. The cholera bacillus that was in the mud of great rivers been genetically modified. It began to reach the local populations who were no longer immune to this variant. This happened to be the year when the armies of the East India Company roamed India, which disseminated cholera, says Dr. Dedet.
Human behavior plays a remarkable role in changing the face of epidemics. For example, in syphilis or AIDS it is sexual behavior that has propagated the epidemic, in zoonoses (diseases from animals that are transmitted to humans) it is human behavior that leads to the crossing of the species barrier, he details. And to cite the example of Ebola or AIDS, two diseases originally linked to the consumption of bushmeat whose animals were sick. “Travel and air travel have allowed infectious diseases to spread faster and more widely,” says this specialist.
Preventing epidemics, essential
“With several thousand micro-organisms pathogenic for humans and the modifications that humans impose (global warming, deforestation) which modify wild pathogenic complexes, there are always outbreaks in store. That’s why monitoring is important.” says Dr. Jean-Pierre Dedet.
This is based on the international health regulations developed by the World Health Organization (WHO) in 1951. These regulations, intended to monitor the birth of epidemics and to standardize responses at the global level, have enabled the program to eradication of smallpox. “However, this surveillance is only effective insofar as all states play the game and declare the birth of an epidemic early. The current Covid epidemic has shown the flaws in this regulation and the need to reform this international health control system”, emphasizes Dr. Dedet.
*Author of Epidemics, From the Black Death to Covid-19Editions Dunod, 2021
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