Rising population, urban lifestyle, deforestation… why epidemics are repeated

Covid, monkeypox (or monkeypox), cases of polio… What has been happening in recent years, and even for several decades? “We are clearly observing an acceleration of epidemics”, notes virologist Xavier de Lamballerie, who spoke this Thursday during an online meeting of the ANRS, the new agency for the fight once morest infectious diseases. There are the viruses that have never been seen in humans causing an increase in emerging diseases. Sras in 2003, and especially its cousin in 2019, responsible for the Covid, which brought the planet to its knees. And the others, already identified, and which regularly give a few isolated cases of poliomyelitis or even epidemics of Zika or dengue fever.

How to explain that new viruses appear and that others re-emerge constantly? “In recent decades, the number of humans on Earth has exploded and their habitat has become essentially urban,” explains the professor. By our extension, we find ourselves more and more in contact with animals, virus reservoirs, that we should never have crossed. As for our proximity, it favors the transmission of the infection. Add to that deforestation and trade.

The Covid, a major adversary

Thus, over the last fifty years, men, animals and plants have been traveling at high speed between the different regions of the globe. So much so that in 2003, when SARS was identified as a public health problem, contact cases had already spread to the four corners of the globe. As for global warming, it will be associated with a change in the distribution of fauna, from migratory birds to certain vertebrate species. So many opportunities given to new and old viruses to emerge or resurface in areas hitherto spared.

So are we doomed to suffer pandemics? “If we want to prevent them, we must take this environment into account,” warns Dr. Muriel Vayssier-Taussat, head of the animal health department of the National Research Institute for Agriculture, Food and the Environment. . How ? By relying on an approach that scientists have been talking regarding for months, that is to say a conception of health extended to animals. “It has been used before and it works. Rabies, for example, was eradicated by vaccinating foxes”, illustrates the doctor. Another possibility: better monitor the appearance of viruses in animals to anticipate their transmission to humans. First, we must understand these complex mechanisms.

Veterinarians, infectiologists, virologists, climatologists, everyone will work hand in hand. The challenge is titanic, the means essential. Over three to five years, the ANRS will receive 80 million euros from the State. While waiting to build this strategy, there remains a major adversary to fight, the Covid. “If we have to be wary of predictions, there will be an increase in cases at the start of winter,” warns Xavier Lamballerie. To limit the impact of this 8th wave, a solution: reach out. “The figures for the 4th dose are not good, only 30% of 60 to 79 year olds have made this reminder, regrets infectious disease specialist Yazdan Yazdanpanah. One of the messages to convey is above all, get vaccinated! »

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