The process of transmitting new viruses from one species to another, responsible for the emergence of all major pandemics in history, is likely to become much more common with the climate crisis, according to an analysis coordinated by US scientists.
According to the work, changes in climate will likely force many animals to move in search of habitats compatible with their survival, creating conditions for them to come into contact with species they had never encountered before. This means that the viruses that these species carry will also have an unprecedented chance of invading the bodies of new victims.
According to calculations made by the team led by Colin Carlson, from Georgetown University (USA), contacts between species previously isolated from each other could result in 15,000 new episodes of virus sharing by 2070, if the current warming trajectory of the planet, caused by human action, does not suffer significant deviations in the coming decades.
“Our work shows that, above all the factors associated with the risk of new pandemics, above deforestation and animal trafficking, there are these monumental changes that are affecting the climate. and they make the risk of new pandemics a problem for everyone,” Carlson told an online press conference.
The American and his colleagues have just published the data in the online version of the scientific journal Nature, one of the largest in the world. The researchers’ estimates refer to a simulation based on the current geographic distribution of nearly 4,000 placental mammals (the vast majority of the group; marsupials such as kangaroos and skunks and the rare egg-laying mammals such as platypus are excluded).
Among mammals are some of the animals that function as major reservoirs of emerging diseases today, such as bats, primates and rodents. Even so, the analysis leaves out another major source of these diseases, birds, whose migratory behavior usually spreads new strains of the flu virus around the world, for example.
Considering the 4,000 species of mammals and the habitats they usually occupy today, American scientists used computer models that help predict how the environment around them will change in the coming decades. In many cases, the animals would need to move because the places they occupy today would be too hot, too rainy or too dry, for example.
Not all species would be able to move in time to keep up with these changes, but those that survived the first hit of environmental changes and found new places would come into contact with prey, predators and competitors they had never encountered before. And, as each animal is a zoo of the viruses that populate its organism, unprecedented exchanges of disease causes would eventually become inevitable.
The simulations indicate that this process will probably happen more intensely in mountainous areas of Southeast Asia and tropical Africa – regions, by the way, that are already heavily affected by emerging infectious diseases.
The vulnerability of these areas has to do with the fact that they bring together a lot of biodiversity and variable altitudes (because of the mountains), which allows animals that live in places that are getting too hot to try to “climb the mountains” in search of cooler environments.
The process, on the other hand, must be less frequent in the Amazon – but for a very bad reason. With much less variation in altitude, since the Amazon basin is largely a superplain, species adapted to less torrid environments would not be able to seek refuge in mountainous regions.
The vast majority of the tens of thousands of virus exchanges are unlikely to lead to the establishment of new epidemics, either among animals or among humans, as many times a new virus cannot adapt to the different host. The problem is that the sheer number of transmissions is so high that some of these viruses can end up being very successful, with unpredictable consequences.
A particularly frightening example analyzed in the research is that of the Ebola virus, which has already caused several deadly outbreaks on the African continent over the last few decades and today can affect 13 species of mammals. The researchers calculate that Ebola alone could make 100 different jumps between species in the period simulated by the study.
In these processes, a potential “wildcard” is bats, animals known to be reservoirs of dangerous viruses and with a much higher average mobility than most mammals – an obvious consequence of the fact that they can fly. In some cases, they are capable of continental-scale displacement.
This is no reason to pursue these animals, of course: the important thing is to intensify the monitoring of viruses that affect biodiversity to know potential enemies and try to prepare quick responses against them.
