About 60% of human pathogens studied are zoonotic; that is, they are transmitted to humans from animals. These are microorganisms that originally infected animals and, due to small mutations, are able to infect humans. Over the past century, an average of two viruses per year have passed from their original host to humans. We are talking about pathogens that cause diseases such as AIDS, Covid-19, swine flu, Crimean-Congo hemorrhagic fever or monkeypox, among others.
But why is this increase in zoonotic diseases happening?
Evidence shows increasing human involvement in Earth’s ecosystems. Activities such as deforestation for the establishment of crops and livestock or for the growth of cities, the trafficking of species and the fragmentation of habitats by the construction of roads alter the balance of ecosystems and reduce biodiversity. Therefore, the development of pathogens, potential hosts and vectors is favored, as they are more comfortable in their environment given the scarcity of other more hostile species. These practices promote the proliferation of species with stronger immune systems, such as rats or bats and other animal reservoirs of pathogens that cause zoonotic diseases.
In addition, this type of behavior generates an increase in contact of humans, livestock and domestic animals with wild animals which can be a reservoir of these diseases. For example, in 2003, the virus that causes the disease known as monkeypox was introduced into the United States in a shipment carrying 800 small mammals from Ghana to Texas. Some of these animal reservoirs infected several prairie dogs which acted as a vector causing the infection of 47 people.
On the other hand, the global climate change that human beings have caused favors the expansion of pathogenic microorganisms and vectors outside their common affected areas due to their preference for humid and warm environments, facilitating the appearance of certain species into new areas where they may carry unknown or eradicated diseases.
Faced with this problem caused by the action of man, we have the responsibility and the urgency to solve it. Especially our generation, who inherited this situation and who really have the power to solve it or at least try to minimize its effects.
How can we achieve this? Betting on more sustainable agriculture and livestock models, preserving the biodiversity of the planet’s ecosystems, monitoring and regulating animal trafficking, stopping the mass extinction of species or reducing our ecological footprint, changing the model of current consumption by favoring local products and, more broadly, understanding that our health depends on the health of our planet.